NATIONALTECHNICAL SEMINAR

ON

Impact and Experience of Heavier AxleLoads on Indian Railways and Resultant

Maintenance Strategies

&

Innovation in Design & Construction of RoadOver Bridges and Road under Bridges on

the Indian Railways

(VOLUME - I)

NATIONAL TECHNICALSEMINAR

ON

Impact and Experience of Heavier AxleLoads on Indian Railways and Resultant

Maintenance Strategies&

Innovation in Design & Construction ofRoad Over Bridges and Road under

Bridges on the Indian Railways

JANUARY : 21 st - 22nd , 2010

PUNE

TECHNICAL PAPERS

Organised by

INSTITUTION OF PERMANENT WAY ENGINEERS(INDIA)

Published by :

Institution of Permanent Way, Engineers (India)Rail Bhavan, New Delhi

Compiled by :

Technical Committee, Pune Centre, IRICENPune

Opinions expressed by authors in technical papersare not neccessarily the opinion of IPWE (I)

C All rights reserved by Institution of PermanentWay Engineers (I)

Printed by :Kalyani Corporation

1464, Sadashiv Peth, Pune - 411 030.

PREFACE

Indian economy is growing annually at the rate of about 8%compounded for the last few years and Indian Railways is targetedto carry 1000 GMT by the end of the 11th Five Year Plan (March2012). With the same trend continuing, Indian Railways has toincrease the throughput by almost double in another decade. Increaseof axle load from 20.3 tons to 25 tons on the existing corridors and32.5 tons on DFC is a step towards meeting the demand of traffic.The studies conducted by UIC and other research organizationssuggest that with the higher axle loads, deterioration of the trackbecomes much faster requiring much greater inputs. The topic of theseminar “Impact and experience of heavier loads on Indian Railwaysand resultant maintenance strategies” is a very apt subject to sharethe experience of the railway engineers, consolidate the same in thefuture maintenance strategy.

Along with the increased throughputs, safety of operations is anothervery important aspect for all railwaymen. Accidents at level crossingshave been an area of concern and the only permanent solution appearsto be to have grade separation at the crossings. Presently constructionof ROBs/RUBs take quite a long time due to the work to be doneunder traffic, accompanied with speed restrictions and traffic blocks.With a view to identify new technologies to construct ROBs/RUBs tobe completed in the shortest possible time with least disturbance totraffic, the second topic of seminar “Innovation in design andconstruction of ROBS and RUBS on the Indian Railways” is expectedto pave the way for expediting the process and construction of grade-separated crossings.

Four technical sessions on the above two topics have been plannedin the seminar. These sessions will provide forum for discussion andexchange of views relating to the technological aspects of theseissues. The technical papers to be presented during the seminar arebrought out in two volumes.

Ashok Kumar GoelChairman, IPWE(I) PuneCentre & Director/IRICEN

Governing Councilof

THE INSTITUTION OFPERMANENT WAY ENGINEERS ( INDIA )

President

Shri Rakesh ChopraMember Engineering, Railway Board &

Ex-officio Secretary, Government of India

Vice President

Shri S.K. MalikAddl. Member, Civil Engineering, Railway Board

Hony. General Secretary

Shri A. K. Gupta,Principal Chief Engineer, Northern Railway

Hony. Treasurer

Shri V.K. Govil,Executive Director, CE/B&S, Railway Board

Chairmen of Zonal Centers1. Shri P. K. Saxena Pr. Chief Engineer, CR, Mumbai2. Shri V. Srihari Pr. Chief Engineer, ER, Kolkata3. Shri S.C. Jha Pr. Chief Engineer, ECR, Hajipur4. Shri S.S. Narayanan Pr. Chief Engineer, ECoR, Bhubaneswar5. Shri A.K. Gupta Pr. Chief Engineer, NR, New Delhi.6. Shri D.D. Dewangan Pr. Chief Engineer, NCR, Allahabad7. Shri Manoj Kumar Pr. Chief Engineer, NER, Gorakhpur8. Shri G.S.Tiwari Pr. Chief Engineer, NFR, Guwahati9. Shri Laj Kumar Chief Engineer(Co-ordn), NWR, Jaipur10. Shri G. Narayanan Pr.Chief Engineer, SR, Chennai11. Shri Pradeep Kumar Pr.Chief Engineer, SCR, Secunderabad12. Shri B.P. Khare Pr. Chief Engineer, SER, Kolkata13. Shri V. K. Sangal Pr. Chief Engineer, SECR, Bilaspur14. Shri D.G. Diwate Pr. Chief Engineer, SWR, Hubli15. Shri G.C. Agarwal Pr. Chief Engineer, WR, Mumbai16. Shri Pankaj Jain Pr. Chief Engineer, WCR, Jabalpur17. Shri A.K. Goel Director, IRICEN, Pune18. Shri Sonvir Singh Executive Director (Track), RDSO, Lucknow.

Executive DirectorShri S.K. Jagdhari

Executive Secretaries, IPWEShri P.K. Sharma Shri S. D. Sharma

ORGANISING COMMITTEE

� Shri A.K. Goyal,Director, IRICEN, Pune & Chairman IPWE(I),Pune Centre

� Shri Suresh Gupta,Dean & Secretary, IPWE(I), Pune Centre

� Shri N.C. Sharda,Sr. Professor/Track-1

� Shri Ajay Goyal,Sr. Professor/Bridges-1

� Shri Naresh Lalwani,Sr. Professor/Bridges-2

� Shri Pradeep Kumar Garg,Sr. Professor/Track-2

� Shri A.K. Agrawal,Sr. Professor/Projects

� Shri S.K. Garg,Sr. Professor/Works

� Shri Manoj Arora,Professor/Tr.Mc. & Jt. Secretary, IPWE(I),Pune Centre

� Shri V. B. Sood,Professor/Bridges

� Shri Nilmani,Professor/Track

PROGRAMME & SEMINAR COMMITTEE

� Convenor

Shri Suresh Gupta,Dean, IRICEN, Pune

� Member Secretary

Shri Pradeep Kumar Garg,Sr. Professor/Track-2

Shri Manoj Arora,Professor/Track Machine

� Members

Shri Nilmani, Professor/TrackShri V.B. Sood, Professor/BridgesShri N.K. Khare, APWShri Shyam Khoche, AXEN2

RECEPTION, ACCOMMODATION &TRANSPORT COMMITTEE

� Convenor

Shri N.C. Sharda, SPT1

� Member Secretary

Shri Ajay Goyal, SPB1 (Transport)

Shri S.K. Garg, SPW (Accommodation)

� Members

Shri V.S. Wadekar, Dy. CE/C/Pune

Shri N.R. Kale, AXEN1

Shri R.L. Wasnik, ADFM

PRESS & PUBLICATIONS

� Convener - Shri Suresh Gupta

� Member Secretary - Shri Manoj Arora, PTM

� Member - Shri Y.K. Singh, PRO/CR/PA

TECHNICAL & SOUVENIR COMMITTEE

� Convenor - Shri Naresh Lalwani, SPB2

� Member Secretary - Shri Pradeep Kumar Garg, SPT2

� Members - Shri Shyam Khoche, AXEN2

EXHIBITION, HOSPITALITY INCLUDING CATERING &CULTURAL PROGRAMME COMMITTEE

� Convenor - Shri A.K. Agrawal, SPP

� Member Secretary - Shri V.B. Sood,PB (Exhibition)

- Shri A. Chandolikar,AP (Hospitality)

� Members - Shri N.R. Kale, AXEN1

TABLE OF CONTENTSTECHNICAL PAPERS

Technical Session 1

Impact of Heavier Axle Loads on Track and MaintenanceStrategies

1. Effects of Increased Loading on Track StructureS.K. Sharma 1.1 - 1.14

2. Challenges Faced in Running Iron Ore Rake on SWRIncluding Severe Ghat SectionK. J. S. Naidu 1.15 - 1.30

3. Impact and Experience of Heavier Axle Loads on IndianRailways and Resultant Maintenance StrategiesHemendra Choudhary 1.31 - 1.42

4. Experience of Running Heavier Axle Loads on KTE-BIN Section and Resultant Maintenance StrategiesRajesh Arora & Vijay Pandey 1.43 - 1.56

5. Experience of Heavier Axle Loads Operations &Maintenance Strategy Adopted by SWR for CC+8+2Axle Load OperationsD.G.Diwate, Vijay Agrawal & P.S. Basha 1.57- 1.71

6. Effect of Enhanced Loading (CC+8+2) on the Track &Rolling Stock on Chennai Division a ManagerialPerspective for RU-AJJ-MAS SectionS.K.Kulshrestha 1.72 - 1.84

7. Heavier Axle Load – Effect on P. Way & ReorganizingTrack Maintenance StrategiesAmit Agrawal, Rajiv Kumar Tanwar & 1.85 - 1.102M.Jayaprakash Reddy

8. Overcoming the Challenges of Weak Formation forHeavier Axle Loads - Formation Rehabilitation byMechanised BlanketingMunna Kumar, Manohar Reddy & 1.103 - 1.122L. N. Reddy

9. Impact and Experience of Heavier Axle Loads onIndian Railway- M.R.Srinivasan 1.123 - 1.132

Technical Session 2

Impact of Heavier Axle Loads on Bridges and Experienceof Running Heavier Axle Loads on other Railways

1. Experience of World Railway Systems for Running ofHeavier Axle Loads with Special Reference to IndianRailwaysM.M. Agarwal & K.K. Miglani 2.1 - 2.25

2. Effect of Higher Axle Loads on Bridges in SouthWestern RailwayR.S. Dubey, Ramesh Kambli & 2.26 - 2.54T.A. Nandakumar,

3. Strengthening of Bridges on Feeder Routes to Easternand Western Dedicated Freight CorridorsV.K.Govil, S.N. Singh & Ashish Agarwal 2.55 - 2.63

4. Formation Design and Specification for Heavier AxleLoads on Indian RailwaysJ. C. Parihar, J.S. Sondhi & 2.64 - 2.89Rajesh Agarwal

5. Impact of Increasing Axle Load on Fatigue Life ofStandard Steel Girder Bridges – A Study Based onRevised Fatigue ProvisionsR. K. Goel & H.O. Narayan 2.90 - 2.107

Technical Session 3

Running of Heavier Axle Loads – The Road Ahead

1. A Total Rail Maintenance Strategy for Heavier AxleLoad RailwaysJoseph W. Palese & Allan M. Zarembski 3.1 - 3.22

2. Strategy for Rail Grinding for Running Heavier AxleLoads on Indian RailwaysPradeep Kumar Garg, Sanjeev Agarwal & 3.23 - 3.36Tushar Pandey

3. Effects of Heavier Axle Loads and StrategicMitigation MeasuresParmeshwar Funkwal 3.37 - 3.51

4. Improved Track Structure and Efficient TrackMaintenance System for Heavier Haul RoutesJ. S. Mundrey 3.52 - 3.75

5. Running of Higher Axle Loads : Challenges,Limitations & Maintenance StrategiesBansh Narain Singh & Ajit Kumar Mishra 3.76 - 3.102

6. Track Management System for Indian RailwaysS.K. Malik & R. Dhankher 3.103 - 3.111

Technical Session 4

Innovation in Design & Construction ofROBs & RUBs on Indian Railways

1. Innovation in Design and Construction of ROBs/RUBson Indian RailwaysV. K. J.Rane 4.1 - 4.7

2. Adoption of Innovative Design for ROB and RUBConstructionSubodh Jain & Raju Bhadke 4.8 - 4.14

3. Innovation in Construction of ROBs – Strategy forMitigating Difficulties & PitfallsH. P. Tripathi & A. K. Tiwari 4.15 - 4.26

4. Enhancing Safety of Subways in Low EmbankmentLevel CrossingsN. K Garg 4.27 - 4.31

5. Methods of Launching of Railway Span in Road OverBridges: Comparison, Evaluation & ImprovisationAjit Kumar Mishra, Jawaid Akhtar & 4.32 - 4.54G. B. Nagendra

6. Innovative Concepts for ROBs over Cuttings in NewLine ProjectsNeeraj Jain & Debasis Konar 4.55 - 4.63

7. Construction of RUB by Box Pushing Method atBishwas Nagar DelhiVinay Singh & S.K.Mishra 4.64 - 4.73

8. Launching of Precast PSC Girders by High CapacityRoad Cranes for Construction of ROB at Rohatak inNorthern RailwayVinay Singh & S.K.Mishra 4.74 - 4.82

1.1

Effects of Increased Loading on Track Structure

S.K.Sharma*

* CAO (C)/ South Central Railway

1.0 Introduction:In 2004, Indian Railways took a historic step which can be calledrevolutionary in many ways. The carrying capacity of goods 8 wheelerwagon was increased by 8 tonnes (CC+6+2) and 10 tonnes (CC+8+2)on selective routes first and later on CC+6+2 loading wasuniversalised on many other routes. Here it is mentioned that 2 tonneswas mentioned as loading tolerances. Two arguments were floatedat that time;

� World over higher loading density has been adopted and thereforeit will be possible on Indian Railways also.

� In any case overloading is continuing sometimes in connivanceof Railway staff, therefore let us legalise it.

These arguments may look to be flawed even to the common senseand that too without any detailed calculations. The theoreticalknowledge was given go by and also the differences betweenconstruction and maintenance technologies beside so many othersocial and economic issues involved was overlooked. If theoreticalknowledge is deficient then it may be because of our lack/gap ofunderstanding or even after that if the knowledge is still not passingthe test of time, it is the right time to give a quantum change in it.Even if we presume that the present theory level is not adequate,

Synopsis: Increased loading density affects track structure in manyways. It may be in the form of higher stresses, higher rate of wear,faster degradation of rail, ballast and formation. Moreover themaintenance inputs have shorter life under higher load. The fatiguelife is consumed at a faster rate and fatigue signs appear too fast tobe ignored only at the cost of serious safety repercussions. An attempthas been made here to assess the effect of increased axle loading/Carrying capacity on Rail stresses.

1.2

then also we may expect an error margin of 20-30% which is sufficientat least for making a good estimate. Also citing this error margin, thetheoretical knowledge cannot be thrown in trash bin. At least wecould have taken a conscious decision knowing fully well itsrepercussions. Here maximum increase of 10 tonnes (CC+8+2) inBOXN only shall be discussed.

2.0 Increase in Axle Load :The tare weight of BOXN wagon is 25 tonnes approximately. For acarrying capacity of 55 tonnes (Total load of 80 tonnes) this increaseof 10 tonnes , the % increase constitute of about 18.18 %. Thus thetotal weight of wagon will be thus 90 tonnes approximately i,e 12.5% increase in Wagon load. The similar increase will be there in axleload and wheel load also.

3.0 Existing Knowledge Level :The bending moment of the rail is calculated from the equationdeveloped by Zimmerman in 19th century which is as follows;

M=0.25 Pe**(-x/l) (Sin x/l - Cos x/l).

Therefore if all other track parameters are assumed as constant,then as per this formula, the bending moment is directly proportionalto wheel load P. Thus M shall increase by 12.50 %. Since the railstresses are calculated by dividing the M by Rail sectional modulus,therefore the Rail stresses shall also increase by 12.5 %.

4.0 Effect of Vehicle Characteristic :The dynamic augment as per IR practice is calculated as per followingformula.

Speed Factor = (4.5 V**2/100000)- (1.5 V**3/10000000), where V isthe speed in kmph.

From this equation, at stationary position or at a low speed, thespeed factor is zero. Also the dynamic augment or speed factor is afunction of speed only neglecting the effects of vehicle characteristics.This situation is difficult to digest and not amenable to any analyticaltools. At stationery or at low speed also, the vehicle characteristicsassumes importance as widely varying from two stage suspensionpassenger vehicle to single stage secondary suspension freightbogies. Here the effect of decorative piece of primary level pads atcrown level can be neglected. Therefore the dynamic loading at

1.3

stationery or at low speeds also assumes importance where atpresent no guidance is available, the vehicle properties should betaken into account.

The K value of BOXN wagon is around 800-1000 Kg/mm. Higher isthe K value and at higher damping ratio the effect is more pronouncedeven at low speed at small wave length track perturbations. At stiffnessof 800 kg/mm and damping ratio of 20%, the Speed Factor may varyfrom 1.1 to 1.2. Therefore the Dynamic augment at a very low speedmay be taken as 1.15.

The net result is that the 12.50 % increase in Rail stresses shall befurther enhanced to 14.37 %

5.0 Dynamic Effects at High Speeds.

A. Indian Railways Practices : The dynamic effects on track iscalculated by Dynamic augment formula as adopted on IndianRailways as given above. If we consider the maximum speed of 60kmph of CC+8+2 rakes, then the Dynamic Augment shall be 0.15.Therefore the Rail Stresses shall increase to a level of 16.53 %.

B. World Scenarios :Whatever practice we are adopting, can atbest be called poor man dynamic analysis which is flawed at variouslevels. The dynamic rail stresses are a function of speed, vehicleparameters and track conditions. Essentially the dynamic effectsmay be characterised as follows:

1. Vehicle-Load both sprung and unsprung, Damping ratio.

2. Track-Imposed frequency

Let us analyse here the BOXN wagon only. There are three modesviz, Bouncing, Pitching and Rolling. For wheel loading effects, theBouncing mode is the most important therefore here only Bouncingeffects only shall be discussed.

5.1 Natural Frequency of BOXN (Hz) :The natural frequency have been measured as under;

Tare (25 tonnes)— 4.1

CC+6+2 (88 tonnes)—4.16

CC+8+2 (90 tonnes) – 2.5

Since these are measured values therefore let us assume that theminimum error will be present in measurements of natural frequency

1.4

in tare conditions. Therefore the natural frequency level of 4.1 isassumed correct and let us adopt it as base value. Since the naturalfrequency varies in inverse square root proportion of total weight,therefore at CC+6+2 level it is calculated as 2.29 Hz and at CC+8+2level it is calculated as 2.161 Hz. The variation of natural frequencyas measured and as calculated is shown as under;

Fig 1 Natural frequency v/s Total weight of a wagon.

The natural frequency as measured and as calculated are very closeat CC+8+2 level, therefore the calculated values bear more semblanceand can be taken as correct values. It also shows that at CC+6+2level, the measured value of 4.16 can not be trusted which means lotof error in the measurements at CC+6+2 level.

Therefore the natural frequency of 2.5 Hz at 80 tonnes level and2.161 Hz at CC+8+2 level can be considered for further discussions.

In design itself, the damping is provided by inclined wedges only.During service, the wedges get jammed due to loss , corrosion, dirtand ultimately jamming. Therefore a value of 5-10% damping is verymuch probabilistic.

If we take up welding defects at 13 m interval then, at the speed of 60kmph, the imposed frequency shall be about 1.28 Hz. The frequencyratio thus comes to 0.512 for 80 tonnes (Up to CC only) and 0.60 for90 tonnes (CC+8+2).

5.2 The Dynamic Effects will be as Follows :For normal loading (CC) for a frequency ratio of 0.512 and dampingratio of 7.5%, the dynamic factor comes to about 1.35 i,e 35 %increase in loading.For increased loading (CC+8+2) for a frequencyratio of 0.60 and damping factor of 7.5%, the dynamic factor comesto about 1.55 i,e 55 % in loading.

4.5

4

3.5

3

2.5

2

1.5

1

0.5

0

0 20 40 60 80 100

BOXN Natural Frequencies

Total weight of wagon tonnes

Nat

ura

l F

req

uen

cy

(Hz)

As Measured

As Caculated

1.5

5.3 Comparison with Indian Railway Practice.By Indian Railway practice, the dynamic augment comes to 15 %while taking in to account of Wagon features, the dynamic effectcomes to 35 % . Therefore on Indian Railways, there is grossunderestimation of 20 % in general in loading and consequently onRail stresses. Similarly in CC+8+2 loadings, the dynamic augmentcomes to 55 %. Therefore the net effect of increased loading is follows:

No. Sub C C CC+8+2

1. Nominal Wagon Load (tonnes) 80.00 90.00

2. Small Wavelength effects 92.00 103.50

3. Dynamic effect as per Wagon (tonnes) 108.00 139.50

4. Dynamic effect taking into 124.20 160.42accounts Small Wavelength effects

5. Dynamic effect as per IR practice 92.00 103.50 (tonnes)

Thus if we increase the carrying capacity by 10 tonnes, the Railstresses shall increase by:

1. 12.5 %. if we take into account the static load only.

2. 30 % if we take into account the small wavelength effects.

3. 51.6 % if we compare IR practice on CC and Wagon featureson CC+8+2 loading.

4. 30 % if we take into account Wagon features on CC and CC+8+2loadings.

5. 74.36 % if we compare IR practice on CC and Wagon features(Including small wave length effects) on CC+8+2 loading.

The net result is that the Rail stresses shall increase by about 74 %by adopting 10 tonnes increase in Carrying capacity.

6.0 Transverse and Longitudinal StressesThe stress model in these two modes has not been standardized sofar except some very loosely defined formulas. The height of ignorancecan be judged from the fact that the joint effects of these three modalstresses are still an enigma for Indian Railways. At lease there isdynamic augment formula for vertical direction, the similar formula isabsent in other two directions. Simply we assume that there is no

1.6

dynamics involved in Transverse and longitudinal directions.

7.0 Contact StressesThe contact between rail and wheel flange should be theoretically apoint. In practice the elastic deformation under high axle load resultsin deformation of steel of wheel and the rail creating an ellipticalcontact area.

Contact stresses are determined by the normal force on the contactarea, while the ratio of the ellipse axes a and b depends on the maincurvatures of the wheel and rail profiles. Inside the contact area apressure distribution develops which is semi-elliptical in shape withhighest contact pressure occurring at centre.

Fig 2 Shear stress distribution at railhead

The concentrated load between wheel and rail causes a shear stressdistribution in rail head as shown in figure above. The contact problemis most serious in case of high wheel loads or relatively smalldiameters.

Eisemam devised a simplified formula to calculate the maximumshear stress in railhead, which is as follows;

max= 4.13 (Q/R)

Where max = maximum shear stress in railhead.(Kg/mm2)

Q = Wheel load + load due on loading due to

curves. (kgs)

R = Wheel radius (mm).

Maximum Contact shear stress occurs at a depth of 5-7mm belowthe rail surface.

1.7

The Contact stress varies in direct square root proportion of wheelload. Therefore a variation of 74 % excess of axle load causes astraight increase of 32 % of Contact Stresses. For 90 tonnes wagongross load and at 813 mm wheel diameter (Worn), the Contactstresses comes to about 21.91 kg/mm2. As per IR practice the maxpermissible Contact stress should be 30 % of Rail UTS. Thisapproach is OK as far as segmental approach is concerned. What isthe overall view when it is combined with bending stresses (BendingMoment is the first derivative of Shear force) is totally a Black holefrom which nothing comes back.

7.0 Wheel and Axle ImperfectionsThe views given above is OK for perfect wheel axle sets. On an averagethe conditions of majority of wheel sets, the conditions are far fromperfect. The wheel axle imperfections generally are :

Wheel flats, Oblong wheels, Bent axles, Worn wheels,Jammed bearingsAll these imperfections cause extra rail stresses. For example if wetry to analyse the wheel flats alone, the extra load on rail dependson: Flat size, Train Speed, Wheel radius and Wheel load

Effects of Wheel Flats :ORE 161.1/RP 3 reports of the tests carried out on flat tyresmeasuring the effects of speed, size, sleeper type and axle loads.The results reveal:

i) The forces at frequencies above 500 Hz referred to as P1 forcesincreases continuously with speed, while the forces at frequenciesbelow 100 Hz, referred to P2 forces are more or less independent ofspeeds. The P1 forces have bearing on wheel rail contact stresses.This force, which causes most of damage to rails and concrete ties,increases with increase in speeds.

Effects of Speed on Wheel Force:

1.8

� The P1 force is largely responsible for Track stresses.

� The P1 force increases from 500 KN to 600 KN if the speed isincreased from 30 kmph to 60 kmph i.e, 20 % increase. The 80tonne total load will become 96 tonne at 60 kmph. It also showshow far we from this figure vis a vis the value of load from ourdynamic augment formula specially at higher speeds.

Effect of Wheel Flat Size on Wheel Force.

� The relationship between the flat size and force is almost linear.

� The increase in Dynamic wheel force is more for concrete sleepersthan for wooden sleepers.

� Let us compare case nos 1 and 3 having concrete sleepers andin winter conditions of 22.5 t and 20 t axle loads. The wheel forcejumps from 28 t to 33 tonnes i.e, 18 % increase at 30 kmph.

� Therefore if we take into account the speed also, then at 60 kmph,the total load shall increase from 96 t to 132 tonnes i.e, 37.5 %robust increase.

Studies have also revealed that movement of wheels with flats cangenerate dynamic forces, as high as six times the normal staticload, in extreme situations. The Dynamic forces increase withincrease in speed and axle loads. On Indian Railways, the effect ofrail/ wheel defects and vehicle suspension, on static wheel load, isrepresented by a speed factor which can assume a maximum value

1.9

of 1.75 for locomotives and 1.65 for wagons. Such occasional highloads may result in higher rail stresses reducing the fatigue life ofrails and causing fracture of rail/ welds in extreme cases. The problemassumes alarming proportions incase of thermit welds (which havethe impact strength of 50-60% of parent rail) in LWR territories, duringwinter season, when the full tensile stresses are present in rail section.

According to UIC leaflet 510-2, flats on wheel with diameter of 1000-630 mm should be restricted to a length of 60 mm and a depth of 0.9-1.4 mm.

Other Wheel Axle and Bogie Imperfections.Track stresses are also related to other imperfections of rolling stocks;

� Oblong wheels.

� Bent axles.

� Worn wheels.

� Jammed bearings.

� Difference in wheel diameters on the same axle or on the samebogie.

� Ineffective/jammed damping system.� Spring characteristics change.

� Condition of couplings.

Even these factors cause greater level of stresses more than sometimewheel flats, no efforts have been made to determine the stress levelincrease due to these factors. Does our ignorance leads us to asituation where we claim that these factors are not important.

8.0 Combination of Rail Stresses :Although algorithms have been developed to determine the effects ofvertical, longitudinal and lateral loadings individually but the variouscombinations are yet to be understood on IR system. All the parts ofrail section profile has to be analysed from various combination pointof view duly supported by practical test data. From this analyses,the mysteries behind rail fractures and weld failures which we havemade so assiduously shall start unfolding. And possibly then we cantake remedial measures.

9.0 Seriousness- a Big Question :Hoe serious we are is clear from half hearted approach which we

1.10

have adopted to stop overloading. Firstly no proper mechanism toinstall and maintain the weigh bridges. Secondly when we talk aboutwheel impact load device, we are told that its technology is not fullyproven therefore we cannot adopt it. Thirdly when we talk to post theC&W staff to check the overloading , Wagon imperfections andconsequently detachment at entry to Railway system, there is hugeuproar and opposition from one particular department.

10.0 Penultimate Scenario :There is 74% increase in Rail Stress level and 37.5 % increase inRail Contact stresses in case we increase the Carrying Capacity by10 tonnes.. However no studies are available whether these two typesof stresses are having any linkages or not. After all the bendingstresses give rise to shear stress and Contact stresses also in shearmode only. If these are directly additive then the increase in shearstresses shall be 112 %. This increase is in relation to actual stresslevel in Carrying Capacity scenario only. What is this stress level inrails?. Well it is a million dollar question. On Indian Railways this railstress level under actual field conditions is still a mystery. Thismystery is yet to be unfolded since we are not in a position to statethe actual Rail stress level under dynamic field conditions with carryingcapacity load of BOXN wagon with any amount of certainty. If we arenot aware and agree on basic stress level under a given load in dynamicfield conditions, any amount of analysis shall not yield useful resultand we shall not lead to any conclusion, leave alone the remedialmeasures to contain Rail fractures and weld failures.

11. Result of this ProfligacyThe result of this profligacy and freedom with track has beendisastrous. An analysis was made on NCR in 2009. The results areexplained here;

11.1 Over the last few months it has been noticed that the incidenceof rail fractures have increased. A detailed analysis of Rail and weldfailure was done to establish the proper cause and implement theremedies. On analysis of the fracture data it was observed that therate and pattern of rail failure has changed in a major way from May2006 onwards. In May 2006 heavier axle load of CC+6+2T wereintroduced over the main line section of NCR.

Therefore in order to analyze properly the effect of heavier axle load

1.11

on the failure pattern of Rails in terms of Rail fracture and weld failure,a detailed analysis of the rail failure pattern, as discussed in thisreport, has been done for the main line sections of all the three NCRdivisions.

11.2 Period of Analysis : The heavier axle load has been introducedover NCR in two stages. The loading of CC+6+2T has been introducedover the main line sections of NCR i.e. MGS-GZB section of ALDdivision and BINA –PWL section of Jhansi and Agra Divisions in May2006.

Later on even further heavier loading of CC+8+2T was introduced inNov ’07 over the MGS-GZB section of ALD division and in April ’08over the BINA-AGC section of JHS division. In ALD div UP directionis the loaded direction while in remaining two divisions DN directionis loaded direction.

To arrive at a comparative position, a total period of 04 years i.e. fromMay 04 to May08 is taken for analysis so that rail failure figures ofcorresponding periods of before and after heavier loading introductionis taken and compared.

Detailed analysis was done between the fracture patterns for 02 yearsperiod before and after of CC+6+2T introduction i.e. from May 04 toMay 06 (before introduction period) and May 06 to May 08(afterintroduction period).

However it is difficult to compare the rail failure figures resulting afterthe introduction of CC+8+2T loading, as there is no correspondingbase figures available, since prior to introduction of CC+8+2T loadingthe loading of CC+6+2T was continuing at all the Main line sections.

11.3 Methodology Adopted: However while doing the aboveanalysis for judging the effect of heavier loading on rail failure behaviourit is noticed that failure data taken for the complete sections is notstrictly comparable. This is because lot of input has been given inthe track in terms of CTR/TRR during the last 04 years in these mainline sections of MGS-GZB and BINA –PWL.

These considerable inputs given in terms of new and heavier trackstructure compensates to a large extent the negative impact of heavierloading on rail failure. Hence while comparing the overall failure figuresof complete sections, true picture of negative impact of heavier loadingis not reflected.

1.12

Therefore to single out the effect of heavier loading on the availabletrack structure, rail failure analysis of only those sections is meaningfulwhere no major input in terms of CTR/TRR etc is given over the timeperiod of comparative study.

Accordingly such sections of NCR were identified and the detailedrail failure analysis of these sections is done before and after theintroduction of heavier loading. The corresponding data and thecomparative rail failure position is given below;

11.4 Data Sheet: Section wise fracture details

Enclosed as Annexure 1

11.5 Results Obtained: Although there are some aberrations in thetrend/pattern but that may be due to local field conditions/othertemporary reasons of the sections.

The results obtained from this analysis can be summarized as follows:-

� The rail failures have increased by almost 75% subsequent tothe introduction of CC+6+2T over the sections where track hasnot been renewed.

� The weld failures have increased by almost 85% subsequent tothe introduction of CC+6+2T over the sections where track hasnot been renewed.

This clearly shows that the negative impact of heavier loading on railfailure is considerable and it increases the rail failure to a very highrate compared to earlier failure rates.

Although it is difficult to quantify but it can be safely concluded thatthe cumulative effect of this increased loading over the passage oftime will further accelerate the incremental failure rate even beyond85% that has been observed in the first two years of increased loading.

The effect of CC+8+2T loading on rail failure will obviously be muchharsher and more steep than that resulted by the introduction ofCC+6+2T.

Therefore it is proved that the heavier loading, which is now CC+8+2Tfor the last 18 months over the mainline sections, has been a majorcause of increased number of Rail and weld failures of NCR.

Though considerable inputs and efforts are being given in terms of

1.13

USFD inspections, improved weld quality and other safety measuresto contain the fracture menace but to reduce the rates of failureconsiderably, will take some time till the system stabilizes with theimpact of heavier loading.

12.0 Conclusions :The 74 % increase in Rail stress level should have been sufficient toring the bell. First there is strong need to develop analytical methodsto calculate the stress level in Rails duly supported by actual fieldmeasurements. After calculating the stress level under increasesaxle load, if it is considered essential to increase the axle load aftertechno economic analysis, we should certainly we should increase.Had this decision been a techno-economic decision, there would nothave been any problem. Was it a conscious decision, keeping inview the stress level increase, increased cost of maintenance, railreplacement costs and safety costs in case of undetected RailFractures and Rail Failures. Unfortunately this was not the caseand the decision was taken without carrying out any detailed analysisand weighting against the economics behind replacement andmaintenance of permanent way.

1.14

Annexure 1 :

S. Section Lenght Total Time Period Rail Facture & weld FailureNo. (Km) (before & After ) details for the section

Where no major input(CTR/TRR etc) is given

1. GHER- 58.28 Total period-May 04 0 4 5 16AGC DN to May 08 Before

Period May 04 toMay 06, After May06 to May 08

2. BLNR- 49.3 Do 9 16 12 24HET DN

3. KQR- 6 Do 2 11 0 3DDA DN

4. KRQ-SLV 63.63 Do 5 2 4 20Up

5. STLI- 11.28 Do 2 5 2 10BLNR UP

6. BTSR- 15.2 Do 0 0 1 3AJH UP

7. MTJ- 3 Do 12 18 6 8BTSR DN

8. ALJN- 4.08 Total Period Nov.04 4 3 1 7MWUE to Nov. 07 BeforeUP Period Nov. 04 to

May. 06;After PeriodMay. 06 to Nov. 07

9. MTI-CMR 16.14 Do 0 0 5 0UP

10. MWUE- 95 Do 2 4 32 35MIU UP

Total 321.91 36 63 68 126

***

1.15

Challenges Faced in Running Iron ORE Rakeson South Western Railway Including Severe

Ghat Section

K.J.S. Naidu*

* CRS/Southern Circle, Bangalore

1.0 IntroductionBellary-Vasco, Bellary-Hasssan-Mangalore are two important ironore routes on S.W.Railway.

Bellary area is full of iron ore mines, large scale iron ore is beingexploited since long years. From Bellary iron ore used to be sent toChennai port through Bellary-Guntakal-Renigunta-Chennai route.Before large scale GC works, Bellary-Guntakal was operated as agoods line in this route. During this period, Bellary-Vasco was onMG route, small quantities of iron ore might have been going toVasco, being MG. on Bellary-Vasco (MG) route trains had to crosssevere ghat section of Castle rock-Kulem where gradient 1 in 37existed. During 1990s, large scale GC works were carried out onindian railways. During this period the line between Bellary-Vascowas also converted into BG. After conversion of this line into BGbetween Bellary-Vasco, large no. of iron ore rakes started going toVasco, being the nearest Port. Neither the Staff of Hubli Division northe Track provided during GC was able to cater to the High Densityof Iron Ore traffic on this Route, particularly so in the Ghat Sectionbetween Dharwad to Vasco (145 Kms), more particularly in severeGhat Section of Braganza Ghat from Castle Rock-Kulem (26.23 Kms).In this Ghat gradient of 1 in 37 continuous compounded by 7 deg. to

Synopsis: This paper deals with Challenges faced in the Maintenanceof Track including Points & Crossings, Bridges in heavily workedIron Ore Route in South Western Railway including severe GhatSection of 1 in 37 continuous grade, compounded by 7 to 8 deg.Curves. Solutions found to mitigate this problem and theirimplementation.

1.16

8 deg. curves continuously, are available. This paper deals withProblems faced, Remedial actions proposed with status of remedialmeasures. This route became the route identified for CC+8+2 in thefirst lot of routes identified by the Railway Board for plying CC+8+2Rakes during May 2005.

2.0 Trend of Traffic on Bellary-Vasco :

2.1 Fig.1 indicates the increase of Iron Ore Traffic in GMT, the increaseis tremendous from almost Nil to 30 GMT in 5 to 6 years time.

The Route between Hubli-Londa is common route for both Bellary-Vasco and Bangalore-Miraj-Mumbai besides Bangalore-Vasco, henceHubli-Londa assumes high importance. This Section carriesmaximum Traffic in S.W.Railway which includes Iron Ore also.Besides this, Dharwar-Londa is a semi-Ghat section having 1 in 80grades (though on paper it is 1 in 100, actually it is 1 in 80) with largeno. of 5 deg. to 6 deg. Curves. Hence, this Route between Dharwar-Kulem can be compared to KK Line, the length of this Section is96.57 Kms. Dharwar-Kulem assumes higher importance as the trafficfrom Vasco Port towards Hubli, Bellary i.e. Coal, Fertilizer etc isalso very high. The Section between Dharwar-Kulem is having LoadedTraffic from both sides, because of this fact this route is more heavilyworked than KK Line. Added to all these factors another importantitem is running of Express Trains along with Minerals and Fertilizerloaded Trains. For these facts brought out above, importance ofstrengthening the Route between Bellary-Vasco was given highest

35

30

25

20

15

10

5

0

2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

Fig. 1 Comparative Figure of Iron One Traffic

1.17

priority in particular to Castle Rock-Kulem and Dharwar-Londa beingheavily worked having Mixed Traffic of both Goods (Mineral) &Passenger Traffic.

Railway Board introduced CC+8+2 loaded Rakes in May 2005 inthis Route. By the time higher axle load was officially permitted inMay 2005, the problem of this critical section was already studiedand solutions were thought of and started implementing.

2.2 Problems Faced in the Section:a) 90R Rails available during MG work were retained during GC

works by Construction Organisation resulted in large scaleRail/Weld Failures. Rail top table damage with both verticaland side wear in Ghat Section of Castle Rock – Kulem sectionwhere 1 in 37 Grades compounded by 7 to 8 deg. Curves exist.

b) Formation Problems: Between Bellary-Hubli-Londa there wereseveral locations having Formation Problems. In this Section,Track passes through BC Soil area more predominantly betweenBellary-Hubli, due to this fact there are several stretches havingFormation problems. The list of location of Formation Problemsas in Table below. Though such problems existed in MGperiod also, Construction Organisation chose not to treat theSoil in the Formation during Gauge Conversion Works. Similarproblem existed between Hubli-Londa as indicated in the listreferred above (refer Table 1 below):

Table 1: List of KMs having Formation Treatment

P.Way Location Km. LengthSection From To

Hubli Dharwar 489/500 490/000 0.50

490/800 491/400 0.6

492/500 493/200 0.7

496/400 498/100 1.5

500/800 501/300 0.5

504/400 506/000 1.6

509/600 510/100 0.5

1.18

511/200 511/800 0.6

515/000 516/000 1

519/000 519/800 0.8

520/200 520/800 0.6

521/400 522/000 0.6

522/400 522/600 0.2

523/300 523/600 0.3

524/900 525/500 0.6

Bijapur 169/000 171/000 2

178/000 182/50 4.5

201/000 202/500 1.5

Total 8.00

Bijapur 95/000 101/000 6.00

165/000 169/000

62/000 98/000 14.4

Total 20.4

Belgaum 612/000 625/10 13.0

Hubli 5 7 2.0

19 29 10.0

Total 12.0

c) Points and Crossings on Wooden Layouts and WoodenSleepers on Girder Bridges:

Throughout the length of this Section between Bellary to Vasco,Points and Crossings were laid using Wooden Sleepers to caterto the Track circuit needs of Signalling. No Wooden Sleeperswere available for replacement. The deterioration of WoodenSleepers both in Points & Crossings and Bridges was veryhigh in this heavily worked Section.

d) Failure of PSC Sleepers in Ghat Section:

PSC Sleepers in Ghat Section between Castle Rock-Kulemwhere the Gradient is 1 in 37 continuous, compounded by 7deg. to 8 deg. Curves, the percentage of broken Sleepers (seeTable blow) had reached upto 48% in some Kms.

1.19

Table 2

Sleeper Damage

(Ordinary, PSC- RDSO T.2496 & 135-B-1979)

Km. No. of Percentage Km. No. of PercentageSleepers of Damage Sleepers of Damage

25 158 10.26 38 182 11.82

26 98 3.36 39 742 48.18

27 139 9.03 40 597 38.77

28 81 5.26 41 453 29.42

29 70 4.55 42 443 28.77

30 90 5.84 43 443 28.77

31 199 12.92 44 361 23.44

32 72 4.68 45 216 14.03

33 178 11.56 46 214 15.65

34 57 3.70 47 200 12.99

35 121 7.86 48 131 8.51

36 134 8.70 49 95 6.17

37 222 14.42 Total 5723 14.87

The type of Failures noticed in the PSC Sleepers are as below:

i) Longitudinal Cracks (along the length of Sleepers)

Photo 1: Longitudinal Cracks in PSC Sleepers.

1.20

ii) Transverse Cracks (along the Circumference of Sleepers)

Photo 2: Traverse Cracks in PSC Sleepers

iii) Cracks emanating from the ferule fixed locally by drilling holesinto the PSC Sleepers to fix checkrails in Curves, during laying ofPSC Sleepers by Construction Organisation. Looks like while drillingholes, the prestressing tendons have got disturbed, this triggeredthe Cracks from this hole to start with. During the course of Serviceperiod these Cracks further developed and propagated along thelength of Sleepers, Cracks also widened.

Photo 3: Damage started from Ferrule fixed for fixingCheckrail.

1.21

e) Rail Damage:The top table of Rail i.e. contact surface of wheel and Rail onRail top table and Gauge face were damaged extensively,particularly so in Ghat Section between Castle Rock-Kulem.On top table of rail tear of surface was seen which must havebeen due to very high contact stresses at Rail – Wheel contactsurface. Along with Rail table damage, abnormally high lateraland vertical wear were also observed. As the Traffic level inGhat Section kept increasing, the life of rail was found to bearound 3 to 4 years, or even less.

Photo 4 : Top Table Damage

f) Points & Crossings laid on 7 deg. Curves in Station Yardsof Ghat Section between Castle Rock-KulemPoints & Crossings have been laid on 7 deg to 8 deg Curves inthe yards located in Ghat Section. Due to this, wear on TongueRails were abnormally high. This problem is compounded bythe layout available on the Ghat Section Yards due to non-availability of Catch Siding, the Trains have to necessarily takeTurnouts. Due to this arrangement, 100% of Trains have totake Turnout without fail hence wear of tongue rail used to bevery high, along with faster deterioration of Wooden Sleepersand hence increasing ineffectiveness of Fittings was noticed.

g) Bridge ProblemsGenerally in Bridges problems were not noticed except in oneof the Bridges of Ghat Section of Castle Rock-Kulem (theproblem was not with the Bridge but due to unstable slopes onDownstream Side). Because of excellent alignment chosenduring construction, not many bridges are there in Ghat Section.

1.22

Even in available Bridges most of them are functioning well.Only one Bridge which is of 1 of 18.3 m. + 1 of 12.29 m.. Girderjust before the Tunnel 1, actually at the mouth of Tunnel i.e.Bridge 69 at Km. 27/3-4 in Castle Rock-Kulem Section hadserious problem of stability of Downstream Side Slope of hills,as it was getting de-stabilised. The Slope of the Hill is slightlysteeper than 45 deg. Every rainy season the width of disturbancewas increasing. During the year 2002, M/s Macefere gave asolution of providing Gabbions at three levels, these Gabbionsby themselves rest on a mat supported on 150 mm Micro pilesat close intervals. As already brought out, over a period, due todisturbance to slopes during every monsoon the pile cap ofthese Micropiles on which Gabbions were founded got disturbed.Though the Gabbion by itself slightly tilted, no failure had takenplace. But the situation indicated that these Gabbions may failduring the course of time. As M/s Macafere did not carry outdetailed analysis to identify the cause of the problem ofdestabilization of Slopes on Downstream Side of this Bridge,Analysis of this problem was found important. This study wasentrusted to Geological Survey of India, Bangalore, who agreedto study and suggest remedial measures. But unfortunately,they could not continue the Study beyond a certain time limitdue to Logistic problem in Forest area of this Ghat Section.Later the problem has been entrusted to M/s Stup, Bombay,who are studying to find a solution. A Paper has been publishedby Author along with Shri A.V. Mittal the then Dy.CE/Bridge ofS.W.Railway in the Journal of Indian Railway Institute of P.WayEngineers published during October 2008 in Vol.8 No.4, thismay be referred to if more details on this is sought.

h) Tunnels There are 16 nos. of Tunnels in the Ghat Section of CastleRock-Kulem through 26 Kms length. The Tunnels are in HardRock. As all the Tunnels are hard rock Tunnels, due to inadequateBallast Cushion, Track is sitting on Rock. To provide 300 mmBallast Cushion in these Tunnels, poses problems of Clearanceboth vertical and lateral. To assess the problem in each Tunnel,the Laser Profile Measuring Equipment available with RDSOwas used. We were the first to use this Equipment. Afterobtaining profile of Tunnels it was found that in four Nos. ofTunnels it would not be possible to provide Cushion of 300 mm.

1.23

2.3 Solutions Implemented in the Section Carrying Iron ORE:This can be split into two Components.

a) In Ghat Section, and

b) In other than Ghat Section.

2.3.1Solutions in Ghat Section :As already brought out in Ghat Section main problems were:

i) Sleeper Damages

ii) Rail Damages

iii) Maintenance of Points & Crossings laid on Curves of 7deg.

iv) Maintenance of Track inside Tunnels.

(i) Sleeper Damages

A survey of Sleepers used in other Ghat Sections of IndianRailways was undertaken particularly in K.K Line of E.Co.Railway, Lonavala-Karzat Section of Central Railway. FollowingTable 3 indicates comparison of Sleepers used in these GhatSections:

Comparison of Sleepers used in other Similar Ghat Sections-

Length Ruling Max. Rails Sleepers Sleeperof Ghat Gradient Curature Density

per KM

CLR-Kulem 25 km 1 In 37 80 60 kg Normal PSC 154090 UTS T-2496 & 135-

B-1979THOSTI BBRVSystem(Equivalent tonormal sleepers)

KK Line 60 km 1 IN 60 80 60 kg PSC-Slack 1818HH gauge

T-4183-86

Karjat- 28km 1 IN 37 5.50 60kg Normal & Slack 1660Lonavala (No HH gauge

Check 60 Kgrail) 90 UTS

From this it can be seen that K.K.Line had designed a Special Sleeperfor Heavier Loads to be used in Ghat Section. The properties are as

1.24

given below in the Table 4.

Table 4 : Properties of Normal PSC Sleepres as compared toheavier Slack Gauge Sleepers

DEFFERENCE BETWEEN NORMAL SLEEPERS AND WIDE BASEDSLACK GAUGE SLEEPER RDSO T- 418-4186

Normal PSC sleeper Slack Gauge Sleeper

Drawing No. T-2496 T-4183 to T-4186

Gauge 1673 (G-3) S-11675mm (G-1)

S-1677mm (G+1)

S-1679mm (G+3)

S-1682mm (G+6)

Shape

HTS Wires 3 ply-18 Nos (3mm) 3 ply-18 Nos (3mm)

Insert (Drg.No.) T-381 (1.55kg) T-3705

Pre-tension force 486 KN 486 KN

Loads for Load test :

Centre top 60 KN 50 KN

Centre bottom 52.50 KN 60 KN

Rail seat 220 KN 250 KN

Moment of Failure 370 KN 480 KN

From the above Table 4 it can be seen that Slack Gauge Sleepers toDrawing NO. T. 4183 to 4186 is heavier, having higher Moment ofResistance, Trials were carried out at Hospet Sleeper Factory ofS.W.Railway by manufacturing Sleepers to these Drawings. DuringTrials the Sleepers failed to satisfy the Bending Test loads prescribed.RDSO suggested slight modifications to reinforcements whenapproached with this problem. After few trials, as suggested byRDSO, the trials were successful in all tests. Meanwhile, Railway

(Under Rail Seat) 154 mm

210 mm

249 mm

150 mm

217 mm

284.2

1.25

Board was approached for premature CTR of 26 KMs in Ghat Sectionof Castle Rock-Kulem with increased sleeper density of 1660 Sleeperper Km. The then ME visited Ghat Section,. On observing thecondition existing agreed for premature renewal during 2006, the Workwas sanctioned in the year 2006-2007.

From the experience, it was also found that Sleeper life gets affecteddue to inadequate Ballast Cushion besides sleeper density. Ballastingwas also programmed, Ballasting posed problem in Tunnels dealt insubsequent Paras.

(ii) Rail DamagesDue to 1 in 37 continuous grade for 26 Kms, the loaded Trains goingdown the Ghat used to brake continuously. Initially, Triple Loco consistof WDG3A were used to take loaded rakes down the Ghat. Lately,coupled WDG4 are being used.

Up the Ghat also, Trains loaded with Coal, Fertilizer are plying in thisGhat Section. Rail damages due to these loaded Trains were veryhigh. These Trains of 58 Boxes were hauled by 7 nos. of Locos ofWDG3A in total (total Tractive Effort of 7 Locos was 283.5 Tonnes),three Locos in front, three locos in the middle and one loco at theend. The total force was very high. With the adoption of WDG4Locos, Five nos. of Locos are being used as Tractive Effort of eachloco is around 50 Tonnes, the distribution of these Locos in the Trainis two in front, two in middle and one at the end.

Due to very high Tractive Effort/Braking Force, contact surface ofwheel and Rail develops very high stresses. Due to these high contactstresses, top table of rail surface was tearing.Rail damage wasabnormal, Rail Wear was very high. Hence it was felt that Headhardened Rails is a must in this situation. In CTR proposals HHRails were proposed. ME also was shown about Rail damage, healso agreed and sanctioned HH Rail for renewal.

Here it is brought out that fractures were not there in this Section asthe Rail was getting worn out faster, the fatigued surface of rail wasgetting removed due to higher wear before cracks from fatigued portionof rail could propagate and result in fracture. But the side wear wasabnormal besides Top table wear. The extent of wear was so high inthis Section that the frequency of Rail Renewal reduces to 3 to 4years time. This 3 to 4 years time is not enough to cater to the cycleof time required to get the Renewals sanctioned following the present

1.26

procedures. Railways need to take appropriate action before it goesout of hands.

(iii) Points & Crossings:As already brought out above, Points & Crossings have been laid on7 deg. Curves during Gauge Conversion of the Section posing seriousproblems in maintenance. RDSO was approached to advise SleeperSpacing to cater to 7 deg. Curves to lay Fanshaped PSC turnoutSleepers as the present design of Fanshaped Turnouts are designedfor laying upto 2 deg. Curves only. Meanwhile, proposals for shiftingof Points to straight was also studied. But loop lengths werebecoming more than 1 Km. Traffic Department also wanted to increasethe loop lengths. Hence shifting of Points to straights was taken upand Wooden layouts were replaced by PSC Fanshaped layouts inStraights eliminating Points on Curves.

(iv) Ballasting to Provide 300 mm Ballast Cushion:During Gauge Conversion proper ballast Cushion was not ensured.For providing ballast cushion of 300 mm, main problem was posedby Tunnels. There are 16 nos. of Tunnels in total in the Section.Tunnel profile was to be measured accurately, as existing, to knowthe problem. A new Laser based Profile Measuring Equipment wasavailable with RDSO which was not used anywhere. It was obtainedand Tunnel profile was measured using the Equipment. Thisequipment uses laser beams to measure the profile. The laser beamemitter rotates 360 deg. so that at each location tunnel profile couldbe measured accurately. Sample results are given in following fig.and Tables 5 & 6. The Photo 5 below indicates the Laser basedProfile Measuring Equipment.

Photo 5 : Laser based Profile Measurement Equipment

1.27

Fig.2 : Sample profile of Tunnel obtained from Profile

Measuring Equipment Table 5

1.28

2.3.2 Solutions In other than Ghat Sections:

In other than severe Ghat Sections, following action was taken:

a) Renewal of 90R Rails : About 100 Kms of 90R Rails wereavailable on this Iron route with not only Speed Restriction of 30Kmph for Iron Ore rakes, but also large no. of Weld Failuresand Rail fractures, the Fig. below indicates the extent. TheseRails were replaced on priority with 10 rail panels further weldedas LWR/CWR. The weld failures and Rail fracture were containedas could be seen from the Fig. 3

Fig. 3 : Rail/Weld Failures on Hubli Division.

b) Replacement of all Wooden Sleeper Turnout Sleepers: Aprogramme was drawn to replace all the Wooden SleeperTurnouts. The balance no. of Wooden Sleeper Turnouts available

Table 6

600

500

400

300

200

100

02003- 2004- 2005- 2006- 2007- 2008- 2009-

04 05 06 07 08 09 10

Statistics of RF-WFNo. of Failure WF

Statistics of RF-WFNo. of Failure RF

1.29

on S.W.Railway were around 1550 nos. Materials required likeTurnout Sleeper for Fanshaped Turnouts, Rail points andCrossings required along with Fittings were assessed and adetailed programme was drawn up to eliminate all WoodenSleeper Turnouts in a phased manner in 3 years time. In this,priority was assigned to Bellary-Vasco, in about 18 monthstime on this route since 2005, the completion was achieved.

c) Replacement of Bridge Timbers: Programme was alreadyavailable to replace the Wooden Timbers on Bridges, this alsowas accelerated and completed.

d) In some sections broken PSC sleepers were noticed in planesection but not to the extent as found in Ghat Section. Thesewere also programmed for replacement.

e) Formation Problems: Though Formation Problems wereavailable in the section as already brought out, there were nostretches under Speed Restrictions, priority was given forTurnout, Bridge Timber replacements. Later work of Geogridstrengthening at some stretches have been carried out, resultshave to be watched.

2.4 Scabbing of RailsScabbing of Rails in other than Ghat sections was very severe, theproblem was not so much on Ghat section though present to smallextant. The then CME/S.W.Railway took appropriate steps andbrought about very high discipline in ensuring Sanding Gear workingin all the Locos with availability of dry sand at all locations, so thatLoco Pilots could easily take dry sand from any station on Platformitself. This ensured total stoppage of Scabing of Rails needingRenewal of Rail prematurely, a very costly asset of Railways, besidessaving Loco which would be getting damaged due to stalling withadded advantage of avoiding hindrance to Traffic Movement.

3. 0 Conclusions

i) Railways while carrying out any work particularly ConstructionOrganization shall carry out survey in case of critical sectionslike Ghat Section and provide appropriate Track structure.

ii) Maintenance Engineers also to keep vigil, compare notes withother Railways particularly in Heavily Worked Routes further

1.30

compounded by Steep gradients, sharp curves for long stretches.If Problems are identified, Solutions could be found. This hasto happen at all levels.

iii) Needs high quality of Materials that are being used in suchheavily worked Sections.

iv) Needs high quality in execution of Works

v) Needs close and appropriate monitoring at all levels.

* * *

1.31

Impact and Experience of Heavier Axle Loads onIndian Railways and Resultant Maintenance

Strategies

Hemendra Choudhary *

DEN(Central) Adra Divn, SER

1.0 Introduction :The running of CC+8+2 load BOXN wagons was introduced by RailwayBoard in certain identified routes of S.E.Railway since 15.05.05,subsequently other routes were also added.

The running of CC+6+2 Ton load BOXN/BOBRN wagons wasintroduced in certain routes of this Railway since Feb’06 & otherroutes were added later on. Now heavy axle loads are in operation inabout 90% routes of SER.

2.0 Higher Axle Load Operation :On SER heavier axle loads are primarily being operated for iron orerakes in electrified routes. The loading of iron ore is being done at 16loading points in Chakardharpur Division, both for domestic steelplants & for export.

Most of the iron ore loading is being done GUA-BARAJAMDA-NOAMUNDI-BANSAPANI sector for feeding the steel plants of TISCOat Tata Nagar, IISCO at Burnpur and DSP at Durgapur and in Barsuan/Kiriburu sector for feeding the steel plants at Rourkela & Bokaro.

CNI-BURN section is basically feeding IISCO at Burnpur & DSP atDurgapur along with small iron factories at Bhaga, Radhanagar,Chowrasi etc.This section is having a traffic of 59.6 GMT.

Synopsis : SER system is extensively covered by routes identifiedfor CC+8+2 or CC+6+2 trains. Here predominant traffic is iron ore.Thispaper presents the experience gained on CNI-ANR (CC+8+2) route.This section is under Adra Division of SER. The paper seeks tocover the problems being faced & offers some remedies for thoseproblems.

1.32

3.0 Impact of Heavier Axle Load on the Basis of the FieldExperience :Based upon the experience gained so far, particularly in respect ofweak spots such as points and crossings, SEJs, glued joints,approaches of level crossings, curves, rubber pads of steel channelsleepers on bridges, AT welds and considering various maintenanceproblems, additional inputs are very much required for the maintenanceof the track those carrying heavier axle load with high GMT.

4.0 USFD Testing in Chandil – Anara DN Line Section & theResults :It is a well known fact that due to heavy axle load running over thetrack, the rails are subjected to more stress and fatigue and resultinginto earlier failure in the form of fractures. It is also a well known factthat in the sections where heavy load is running, the magnitude ofalertness is high and when deterioration of rails is detected thenneed based renewal is also approved by the head quarter. By suchearly renewals and timely actions , sometimes it is understood thatthere is not much effect of heavy load over the track because numberof fractures are not increasing much in recent time due to timelyattention by the Permanent Way Engineers. The detailed study ofUSFD results of CNI-ANR DN line section considering the age of therails, GMT carried ,and new defects noticed during recent testing isbeing presented.

Comparative Study of USFD Rail/Weld Testing Work BetweenANR-CNI DN Line

S. Item 2004-05 2005-06 2006-07 2007-08 2008-09No.

1 Sectional GMT 28.98 39.39 41.66 55.35 59.60

2 Rail TestingFrequency Rail=4 Rail=4 Rail=6 Rail=6 Rail=6Round/ Round/ Round/Yr. Round/Yr. Round/Yr.Yr. ATW= Yr. ATW= ATW= ATW= ATW=Every Every Every Every Every4Yrs. 3Yrs. 3Yrs. 2Yrs. 2Yrs.

3 Total Length of the 52Kg=12.5 52Kg=8.5 52Kg=3.5 52Kg=3.5 52Kg=2.7Track laid with Km, 60Kg Km, 60Kg Km, 60Kg Km,60Kg Km, 60Kg

=69.4Km =71.4Km =74.4Km =74.4Km =75.2Km

4 A IMR(Rail) 5 4 5 1 5

B IMR(weld)ATW&FBW 2 3 28 2 15

1.33

C OBS Rail 255 209 165 118 98

D OBS(weld) ATW&FBW 183 59 63 65 277

E Defects in centralportion 445 275 193 72 90

F Defects in GF & NGF Data Data 68 114 305notavailable notavailable

G Total No. of defects 445 275 261 186 395

H No. of Rail fracture 7 2 NIL 1 1

5. I ATW Population 9485 9130 8440 8502 8657

J Tested During the year 4657 4828 617 1579 7712

K No. of DFW defected 88 63 17 185 355

L % Increase or Decrease - 0.60% 1.50% 1.70% 2.90%

M No. of weld failure 8 2 2 3 3

N Defects % 1.90% 1.30% 2.80% 1.70% 4.60%

Note:Rails: Due to on going rail renewal programme, the No. of defects in52Kg Rails is decreased substantially apparently it looks that theNo. of defects in rails are in decreasing trend but the fact is that theNo. of newly generated GF/NGF defects especially in AT Welds areincreasing rapidly. The systematic & efficient USFD testing workaccompanied with the prompt action taken by the maintenance staff(i.e. Sectional PWI) minimizes the occurrence of Rails & Welds failurein the section.

Welds : Due to increase in GMT by almost 38% along with HeavyAxle Load, the No. of DFW defects is increasing at a rapid rate of3% which may consider as quick deterioration of AT Welds in thesection.

The Details of USFD Testing of Rails During Period From08/08/2009 to 22/08/09 Between ANR-CNR Dn Line

S. Rail No. Appr- Defects Defects Defects Defects DefectsN0. Section / of ox detected Position in gradient propa

Year def- GMT gationects Carried rate

tilldate New Old

Mid AT Mid AT Cen- GF/ St Cu- L Up/ Slow Fa VeryW W tral NGF rye Dn st Fast

52 Kg1 before 3 600 - 2 - 1 1 2 2 1 1 2 1 - -

1997

2 60 Kg/ 2 600 - - - 2 - 2 2 - - 2 2 - -1996

WE

LD D

EFE

CTS

RA

IL D

EFE

CTS

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3 60 Kg/ 21 560 - 6 - 15 - 20 19 1 3 17 8 4 21997

4 60 Kg/ 1 520 - - - 1 - 1 1 - - 1 1 - -1998

5 60 Kg/ 11 480 - 7 3 1 1 9 10 - 1 9 6 1 21999

6 60 Kg/ 2 440 - 2 - - 1 1 2 - 1 1 - - -2000

7 60 Kg/ 14 400 - 2 1 11 1 12 12 1 3 10 8 1 12001

8 60 Kg/ 7 360 - 1 - 6 - 7 6 1 - 7 5 1 -2002

9 60 Kg/ - 320 - - - - - - - - - - -2003

10 60 Kg/ 1 280 - - 1 1 - 1 - -2004

11 60 Kg/ 2 240 - 1 - 2 1 2 1 -2005

12 60 Kg/ 1 200 - - - 1 - 1 -2006

13 60 Kg/ 1 160 - - - - 1 - 1 1 - -2007

66 - 21 5 40 4 57 57 7 12 51 33 9 5

Detailed Study Report of Rail Defects Between CNI-ANR DN Line(km - 395/20-364/0) During 08/08/2009 to 22/08/09

SI. Rail Section/Year Total Approx Total Defects No. of NewNo. Length GMT No. of Track New defects

(km) carried till defects Kilo- defects Tracktesting metre Kilometre

1 52 Kg/Before2000 2.7 600 3 1.11 2 0.74

2 60 Kg/1996&1997 22.7 600 23 1.004 6 0.26

3 60 Kg/1998&1999 10.3 520 12 1.16 7 0.68

4 60 Kg/2000&2001 13.8 440 16 1.15 4 0.29

5 60 Kg/2002&2003 8.3 360 7 0.84 1 0.12

6 60 Kg/2004&2005 8.8 280 3 0.34 1 0.11

7*** 60 Kg/2006&2007 1.4 150 2 1.43 Nil ------

Remark: Due to very small amount of length i.e. 1.4 Kms, SI. No. 7is not taken in to account during the time of this analysis. Though itis quiet clear that the defect generation rate is directly proportional

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to the age of the rail, that is GMT carried by that particular rail section,but there is slightly variation noticed against SI No.2 due to existenceof a small patch of Head hardened rail in that particular section.

GMT Carried

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From above graphs based on the detailed study of defects in (CNI-ANR) DN LINE, it is clear that total defects are on rise trend with theage of the rails.Here the effect of heavy axle load could be understoodby the new defects. The rate of the defects is increasing afterintroduction of heavy axle load.

Further it is to be noted by USFD testing that the size of the defectin the Rail section is increasing with the time on such routes thoseare carrying heavy axle load.

5.0 Problems Being Faced in Maintaining the Track due toRunning of Heavier Axle load:

5.1 Rails:

i) CORROSION: It has been noted that due to falling of ironore, rate of corrosion has become faster on rail, MS liner &contact area.

SOLUTION: To over come this problem new rails are beingpainted with red lead on side before laying.

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Also in service rails are painted with anti- corrosive paintalong with sealing of liner contact area on gauge face sideusing grease graphite to prevent development of corrosionpits on rail foot. This requires additional manpower &expenditure.

ii) SCABBING/WHEEL BURNT CASES: Due to stalling oftrains/sudden breaking, there is increasing trend of railsgetting damaged on account of scabbing/wheel burns.

SOLUTION: Rails need to be changed on such spots. Theexperience of relaxing such spots by Micro flow thermalspray (using flow alloys) technique has not been good formain line. So, it is better to change the rails. The scabbedrails/wheel burnt rails can be used in the yard/sidings afterwelding by this technique of the affected area.

5.2 Fittings:

GR Rubber Pads: The crushing of GR pads is very fast requiringfrequent renewals (once in 02-03 years). Now, we should think aboutthe use of 10 mm GR pads with improved materials in place of existing6 mm GR Pads.

Further, the main problem of rubber pads getting crushed rapidly isunder CMS X-ings. The rubber pads under crossings are found to begetting crushed within a period of 09 to 12 months.

Rubber pads under crossing with more thickness 10-12mm & withbetter material should be used. It needs a review by RDSO.

5.3 Insert Liner, etc: The design of the inserts & ERCs should bereviewed to suit 10 mm thick rubber pads. Similar is the case withrubber pads used under channel sleepers. The thickness of the rubberpads to be used under the channel sleepers may be upto 20 mm.

5.4 Points & Crossings:

i) With the introduction of heavier axle load, the rate of wearon crossings has increased, thereby need to carry outreconditioning more frequently.

ii) Replacement of crossings also to be required within a periodof 4 – 5 years (200 GMT).

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iii) The GR sole pad under the crossings are getting crushedat a very faster rate & remedial action is only to replacethem frequently. There is need to develop new vendors forsupplying Rubber pads or augmentation of capacity of theexisting vendors to cater the need.

iv) The thickness of Rubber pads under CMS crossing shouldbe increased upto 10-12mm & also the design of inserts &ERCs are to be modified accordingly. It is required becauseCMS X-ing works as a monolithic structure & there are nochances of bending of CMS crossing like rails, so all thevertical force goes to sleepers & from sleepers to ballast &from ballast to formation. Rubber pad acts as a resilientmedia between Rail & sleepers. So, it should be thick &adequate.

v) The heavy wear on tongue rails:Introduction of thick webswitches essential for the routes subjected to heavier axleload.

Provision of short check rails ahead of switches located oncurves has given considerable relief in Chandil , Biramdihand Urma yard.

vi) Frequent changing of pandrol clips is needed (09-12 months)in CMS X-ing due to its monolithic structure.Althoughrecently provided GJ clips have been a better relief.

5.5 Bridges:

i) No major problem in maintenance of bridge has been feltdue to heavier axle loads in this section. However,Instrumentation tests have been conducted for substructure& super structures of two important bridges (Br.No. 414 -5X100’+1X80’ & Br.No. 520-22X100’).

ii) Frequency of attention for tightening of channel sleepersfittings have been increased from once in six months totwo/ three months.

SOLUTION : To prevent frequent loosening of nuts on channelsleepers, the design of nut should be modified & the castlenut may be used.

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A castle nut has 06 number grooves on one side of simplenut & a pin is passed through the grooves of the nut intothe bolt.

iii) Free rail joints are also weak structure & they are difficultto maintain due to severe impact of heavier load & effortsare to be made to eliminate rail joints wherever possible.

SOLUTION: As per provisions of LWR Manual, LWRs arenot permitted through deck bridges so one metre longfishplates are being used to reduce the impact on suchjoints. Alternative solution may be to permit continuingLWR through deck bridges with permanent speedrestrictions in the interest of better maintainability and alsoto prevent damages to bridge structures. RDSO may gofor investigating into this concept.

5.6 Rail WeldingWelded joints in rails are the weak links. Thermit welds are weakerthan flash butt welds by 40%. It is important that population of thermitwelds vis-à-vis flash butt welds is controlled.

The solution lies in using 10 Rail panels & 20 Rail panels in thepresent & future renewals.Quality of AT welding, needs to be improved.

It is also a known fact that AT welds are weaker links on rail track &there are guidelines to replace the AT welds when it attains the halfof the life of the rail but many times AT welds have failed at earlierthan the 50% of the fatigue life of the rails.

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In a long run, we should think in the direction of movable flash ButtWelding plant, so that field weldings can be done as Flash Butt.

6.0 Infrastructural Improvement Required to Maintain TrackSubjected to Heavier Axle Load.

i) To improve the life of CMS crossings and also to reducethe incidences of breakage, deep screening of points &crossings has to be carried out by deploying machine, asmanual deep screening is not of much use. Each zoneshould be provided with exclusively two BCMs for deepscreening of Points and crossings along with UNIMAT &DTS.

ii) Despite monitoring, instances of overloading continues.Clear policy directives are required to be issued fromRailway Board to handle such rakes on detection ofoverloadings.

iii) There is immediate need to create a “Small Track MachineOrganization” for effective handling & utilization of smalltrack machines.

iv) Discipline in loading upto the prescribed limits is the needof the day. The existing penal charges for overloading arenot sufficient deterrent & other punitive measures includingcontrol on indents are also required.

v) Increased axle loads generate high contract stressesbetween rail and wheel, specially where rail table profilehas degenerated. Preventive rail re-profiling by rail grindingat committed intervals to reduce contact stresses betweenrail and wheel may have to be introduced.

vi) Regular re-profiling of wheels and rails to a conformalcondition to specifically avoid high stress contacts mayhave to be introduced.

vii) The actual gradient in some sections do not match withthose mentioned in the load table of the working timetable. It is necessary to identify such difficult sections &provide adequate power for hauling of the trains in suchsections to prevent stalling and wheel burns.

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viii) In stretches where wheel burn & wheel scabbing isprevalent, premature track renewal may be permitted.

ix) As the presence of small defects in track parameters getmagnified quickly on heavy axle load routes, the standardof track maintenance has to be improved. Better trackmachines, lower track tolerances and the system of corridorblocks are to be ensured.

x) Friction management protects the rail gauge face and wheelflange while ensuring good traction on running surface forwhich way side lubrication is recommended.

xi) While the rail removals have increased, the actual railfractures have not increased to the same extent becauseof increased alertness and timely renewals. This has beenpossible only because of extensive patrolling being donevirtually around the year. This is leading to a significantloss in manpower, which needs urgent recoupment.

xii) Gate keeper, Keyman & patrolman should be put in theseparate categories & they should be provided with extraallowance for their tough duties.

It will be better if these three categories are put together &called tough duty trackmen & they are recruited throughRRB directly with better pay & allowance and promotionalaspects.

xiii) Wheel Impact Load Detectors are to be installed atconvenient locations, not only to detect the axle load ofthe loaded wagons but also to detect wheel flats, if any.

xiv) Frequent USFD testing of complete rail head by newtechnology (e.g. walking stick of M/s Sperry) is to beinsisted upon.

xvi) We have to ensure better quality and frequent renewal ofrubber pads and providing weldable CMS crossings & thickweb switches to reduce the wear of their fittings.

xvi) We have to mechanise all the P.Way activities in phases.

This technical paper is based on my experiences gained of heavyaxle load in CNI-BURN section. Heavy axle load is the need of the

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day, so now it is our responsibility to find the ways of bettermaintenance of our assets & I hope my this Paper will Contributesomething, May be little, to find the ways for better maintenance ofthe track.

* * *

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Experience of Running Heavier Axle Load on KTE-BIN Section and Resultant Maintenance Strategies

Rajesh Arora *Vijay Pandey **

*CTE/West Central Railway*Sr. DEN/West/Jabalpur.

Synopsis : Axle load on track is increasing continuously. Developingnewer ways of track maintenance is the need of the hour. In thispaper the authors have presented case study of KTE-BIN section ofWest Central Railways. The effects on track due to running of higheraxle load in KTE-BIN section have been studied in detail and bettermaintenance practices have been suggested to minimise the illeffects. This paper will serve as a guideline to the PWay engineersinvolved in the maintenance of high axle load routes.

1.0 Introduction :Heavy axle load has the same effect on track that heavy physicalstress has on humans. It takes time to notice the ill effects in boththe cases. Initially the track may be able to bear the higher load andto some, it may appear perfectly normal. However, the stresses keepon building inside the rail and may collapse on a later date. Therefore,it is high time that we study the effects of higher axle load on track indifferent sections all across the Indian railways to conclude the illeffects of higher axle load and then, arrive upon a commonmaintenance strategy to combat the same.

Indian railways are a commercially social organisation. While it hasthe responsibility of carrying passengers from and to all corners ofthe country, it also has to care for its economic health and earnrevenue. It is already known to all that major chunk of railways revenuecomes from freight services. And with the ever increasing prices offuel, the pressure of not increasing the freight rates and the constraintof most of the sections running to full capacity, the only way forrailways to keep them into business is by making the same goodsrake earn some extra revenue, obviously, by carrying some extraload. This means that increase in axle load is an irreversible process

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and the higher loading is here to stay, infact, grow further.A typical axle running over the track looks like as under:

The load gets transferred from the axle of the rolling stock in followingmanner:

Rail

GR Pad

Sleeper

Ballast

Formation

2.0 Brief about BIN-KTE SectionTo conduct the study and find out the effect of higher axle load, firstand the foremost requirement is a defined section. Precise and detailed

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study can only be done when the area of interest is well defined andof manageable length. For the purpose of this study, the authorshave selected Bina-Katni (hereafter called BIN-KTE) section of WestCentral Railway. The section is 260 km in length and falls under D-spl route category. Heavily loaded with freight trains, the annual GMTof this section in loaded direction (UP road) is 63.23. CC+8+2T loadshave been plying in this section since May’2005. The chief transportcommodity of the section is coal and the common rolling stock isBOXN wagon. Loaded BOXN rakes of coal do ply on DN road alsobut they are lesser in number and the annual GMT on DN road is26.99. The ruling gradient on UP and DN road is 1 in 200 and 1 in 100respectively while the sectional speed is 100kmph.

3.0 Period of StudyCC+8+2T loads started plying in this section from May’2005. Theperiod of study had to be decided keeping two aspects in mind:

i. Equal representation is given to data of pre and post CC+8+2Tloading.

ii. Availability of reliable recorded data.

Based on the above two aspects, a study period from year 2003-04to year 2008-09 was arrived upon. Much older records were notmaintained properly and therefore not considered for study.

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4.0 Effect on RailThe effect of higher axle load on rail is most visible and best recorded.Rail is also the most important part of the track structure and theeffect of higher loading is more damaging on it than on any otherpart. The rail can also be called as first line of defence of the trackagainst the incumbent load. It directly bears the brunt of the loadwhich is reflected in the form of scabbing, battering of joints, sidewear and fractures. The effect of higher loading on rail was studiedfor following parameters:

i. Rail fractures and weld failures

ii. USFD results

iii. Wheel scabbing

iv. Flattening of inner rail on curves

v. Side wear of outer rail on curves

vi. Effect on glued joints

vii. Wear and tear on turnouts

4.1 Rail fractures and weld failuresThe most difficult task in the study of rail/weld failures is the availabilityof correct data. In this respect, following approach has been adopted.In sub-division/Division unit record of USFD testing along with numberof IMR/OBS/DFW detected and removed during the month ismaintained regularly. While there is no discrepancy in records ofIMR/ OBS/DFW, large discrepancy is observed in reporting ofoccurrence of Rail/Weld failure. Main plea behind the discrepancy isstated to be that “There are number of rail/weld failures, which do noteffect the train operation, termed as rail crack/weld crack and beingreplaced without reporting to traffic.

The discrepancy in date due to above reason gives a totally differentpicture than the actual and would have defeated the very purpose ofthe project. In order to obtain correct picture, field data maintained inthe form of “Section register of PWI”, correspondence between PWI/AEN/Division and progress reflected through PCDO was collectedand scrutinized. Scrutiny of basic field record gives the true pictureof actual occurrence of rail/weld failures during last 5 years for BIN-KTE section (5 PWI units).

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For the comparision of rail/weld failures, locations where rail renewalor deep screening, TSR, etc has been done, were not considered.This is because, the rail/weld failures not only depend on the railitself, but also on other factors like quality of packing, destressing,shifting of liner seat, etc. The year wise rail/weld failure detail forBIN-KTE section including the effects of higher axle loads is given asunder:

Total RF/WF on BIN-KTE section.(Excluding track renewal locations)

Type of 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09fracture

RF 3 7 4 6 7 8

WF 97 106 135 172 208 221

Total 100 113 139 178 215 229

The analysis clearly shows that the failures are increasing everyyear. However, this increase is mainly due to the weld failures. Thismeans that, while the rail is able to bear the increased loading quitesatisfactorily, it is the AT welds that is ringing the alarm bell. Theimpact of increased loading coupled with passing of occasional minorflat tyres is causing more and more welds to fail. This may be primarilydue to rapid loss in the strength of weld under the impact load ofCC+8+2T loading. As a good maintenance practice, we shouldincrease the frequency of weld testing through USFD. This will helpin protecting the welds which are likely to fail. Moreover, the limiting

2003-04 2004-05 2005-06 2006-07 2007-08 2008-09Year

Fra

ctu

res

Total RF/WF on KTE-BIN section

250

200

150

100

50

0

RF

WF

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value of flat tyre should also be revised for higher axle loading routes.

4.2 USFD Results :Year wise compilation of USFD flaw generation has been studied.During the period of the study, through rail replacement was done atsome locations and therefore, for a meaningful study, year wise USFDflaw generation has been compiled only for those locations whererail continued to be the same.

Description 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

UP DN UP DN UP DN UP DN UP DN UP DN

IMR (Rail) 16 13 22 10 7 1 27 14 21 6 12 5

OBS (Rail) 116 68 43 56 91 111 135 159 194 123 164 74

IMR (Weld) 5 1 5 5 8 6 2 2 6 7 1 0

OBS (Weld) 215 148 134 148 521 481 299 514 682 538 639 381

DFW 538 144 422 289 663 361 470 746 466 453 349 165

GFC testing was started in the year 2006 and therefore, comparisonof GFC flaws cannot be done for pre and post CC+8+2T period. Thisis the reason why GFC flaws are not appearing in the above table.From the table it is very clear that number of new flaws gettinggenerated in rails/welds every year is much higher after 2005-06.This is primarily due to the running of CC+8+2T loads since May’2005.

4.3 Wheel Scabbing :Wheel scabbing occurs when the hauling loco is not able to pull thetrailing load. Preceded by wheel stalling, this phenomenon normallyoccurs on a gradient or on the approach of some stop signal wherethe effective trailing load increases. The wheel stalling and railscabbing data of BIN-KTE section during the study period is tabulatedas under:

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Description 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

Lengthof rails 57 54 191 253 289 719replaced (m)

The data clearly shows that the problem of rail scabbing is increasingever since the introduction of CC+8+2T loading. All the wheel stallingand consequent rail scabbing cases have occurred on rising gradients.The problem is more acute on DN road due to steeper gradients.Now, there are three governing factors in this case:

i. The steep gradient

ii. The trailing load

iii. The power of the hauling loco

Of the above three, gradient is a permanent feature. This clearlymeans that if the trailing load is to increase due to the increase inloading, it must be supported with similar increase in the power ofhauling loco to negotiate the gradient of track. And this is exactlywhat is not happening in BIN-KTE section. Even when the trailingload has increased substantially (approx 500T per rake) the haulingpower continues to be the same. As a result, the wheel stalling aswell as rail scabbing cases are on a continuous increase. The remedyto the problem lies in providing adequate hauling power or a bankerto the loaded rake.

NO

. OF

CA

SE

S

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4.4 Flattening of Inner Rail of CurveWhen a loaded rake runs at a speed slower than the design speed,it causes flattening of inner rail of curve. 26 curves were selected forthe study. Vertical wear of inner rail of these curves has been measuredsince the start of CC+8+2T loading. Increase in average vertical wearof these curves with time is tabulated as under:

Year 2005-06 06-07 07-08 08-09

Average vertical wear in mm 2.08 3.21 4.67 5.81

The data shows that the flattening of inner rail of curve is increasingat an average rate of 1.25mm per year. A rail, will therefore, be due forrenewal in a period of around 10 years. Thus, the life of rail is gettingreduced.

4.5 Side Wear of Outer Rail of CurveThe cant deficiency of a curve is responsible for the side wear ofouter rail of curve. However, the increased axle load causes furtherincrease in side wear by increasing the force. The study wasconducted over a set of 33 curves, the side wear of which were beingmeasured since the start of CC+8+2T loading. Increase in averageside wear of these curves with time is tabulated as under:

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Year 2005-06 06-07 07-08 08-09

Average side wear in mm 1.86 4.19 5.84 6.60

The data shows that the side wear of outer rail of curve is increasingat an average rate of 1.58mm per year. A rail, will therefore, be due forrenewal in a period of around 6-7 years. Thus, the life of rail is gettingreduced. As a good maintenance practice, frequency of greasing ofouter rail of curve should be increased.

4.6 Wear and Tear on TurnoutsThe wear and tear on various turnouts over the years is explained inthe following table:

Description 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

No. of tongue rails 36 51 126 114 119 119reconditioned

No. of tongue rails 32 39 99 76 80 68replaced

No. of crossings 48 87 132 155 155 185reconditioned

No. of crossings 42 53 50 63 73 73replaced

The tongue rail of a turnout wears out due to the inherent curvature.As a preventive measure, all main line turnouts of BIN-KTE sectionwere provided with check rails near the SRJ during July to Sept 2007.The idea was to reduce the wear in the first two meter length of thetongue rail. The results have been encouraging. The cases ofreconditioning or replacement of tongue rail have reduced after theprovision of check rails. However, as a measure of systemimprovement, we must only provide thick web switches on CC+8+2Troutes.

The crossing of a turnout wears out due to the impact load as aresult of the wheel jumping from the throat of crossing to the nose ofcrossing. The cases of reconditioning or replacement of crossingshave been increasing every year. This means that the impact load iscontinuously increasing. The life of crossing may be increased if,through some means, this impact load may either be decreased or

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dissipated. Increasing the elasticity of track at crossing portion maybe a good idea. Some of the ways of reducing the impact load are:

� Use of thick rubber pads.

� Improving the ballast cushion.

� Providing gapless frozen joints.

� Eliminating the vertical and lateral misalignment at crossings.

4.7 Effect on GR Pad :GR pad serves as an elastic medium which reduces the impact onthe sleeper. It absorbs the energy by getting deformed under thewheel load. Besides, it also has a role to play in providing correct toeload on the rail. However, due to increased loading, the deformationof the pad increases. The life of rubber pad gets reduced due to thisphenomenon. A sample study done in BIN-KTE section showed that30 to 40% of the rubber pads are crushed at locations where CTRwas done in the year 2006. However, the GR pads were found allintact at locations where TFR has been recently after the year 2008.The life of the rubber pad gets further reduced if they are not centrallyseated over the sleeper. This is because when the pad gets dislocated,the effective bearing area gets reduced and the compressive stressincreases. Therefore, as a matter of good practice, care should betaken while placing a new rubber pad over the sleeper. The dislocationof rubber pad can also be avoided by pasting the pad on the sleeperwith epoxy or similar glue. RDSO may also like to design sturdierrubber pads for such routes.

4.8 Effect on Sleeper :No noticeable effect has been seen on sleepers, other than that onlevel crossings, due to the running of CC+8+2T loads. This is becausethe effect of axle load on sleeper largely depends upon the conditionof rail, rubber pad and ballast cushion. Casual renewal of sleepers isdone routinely at isolated locations which are mostly due to eitherrounding off of sleeper bottom or breakage of CI insert. This is moreof a maintenance problem and therefore cannot be attributed to higheraxle loading.

However, on level crossings due to caking of ballast, the impact onsleeper increases and hence groove formation takes place at the rail

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seat. During the overhauling of level crossings, more and more casesof unserviceable sleepers are being noticed. The details are tabulatedas under:

YEAR 2003-04 2004-05 2005-06 2006-07 2007-08 2008-09

No. of sleepersreplaced at LCs on 50 37 33 77 129 260BIN-KTE UP road

To reduce the groove formation on sleeper rail seat at LCs, followingmay be done:

� Track at level crossings should be deep screened at a reducedinterval

� Spacing of sleepers at LCs should be reduced

4.9 Effect on Ballast :Higher impact loading damages the ballast by crushing it. This causesan increase in the proportion of fines (<20mm size) resulting in cakingup of ballast. To study the effect of higher axle loading on ballast, itsgradation was analyzed and compared with new ballast. Locationswhere TBR has been done in recent past were selected for this purpose.The results are tabulated as under:

The results clearly show that the proportion of fines has increasedsubstantially with time (four times in case of deep screening done inthe year 2004. though, this phenomenon of crushing of ballast cannotbe stopped, still, as a measure of good maintenance, frequency ofshallow screening should be increased and availability of rubber padsshould be ensured.

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4.10Effect on Formation :Formation behaves like the foundation of track and any damage to itcan severely affect the track parameters. Ironically, the materialstrength of formation is the least as compared to other componentsof track. This is why the deterioration of formation increases rapidlywith increase in axle load. 25 km length of BIN-KTE section (KM1100 to KM 1125) is considered to have formation trouble. Number ofattentions required by the gangs at these locations over the years istabulated below:

Year Road 2003 2004 2005 2006 2007 2008

No. of UP 16 33 76 105 124 138attentions

The permanent remedy to the problem lies in strengthening of formationthrough various formation treatment works. However, as a measureof better maintenance, correct and wider cess, along with side drains(in cuttings) must be provided at such locations. Also, zero missingfittings should be ensured at such locations. The rate of deteriorationof track parameters at the location of weak formation is much fasterand any misalignment or unevenness only worsens the situation.The solution lies in maintaining a straight alignment and zerounevenness. Increasing the frequency of machine tamping at suchlocations also helps to a great extent.

5.0 SuggestionsThe effect of higher axle loading on track can not be eliminated.However, through various maintenance efforts, P Way engineers can

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reduce the effect of higher axle loading. Some of the steps that canbe taken in this regard are:

� Increasing the frequency of weld testing through USFD. This willhelp in protecting the welds which are likely to fail.

� The limiting value of flat tyre should also be revised for higheraxle loading routes. The larger the flat, the larger is the impactload and therefore higher the weld failures.

� Providing adequate hauling power or a banker to the loaded raketo prevent the scabbing of rails. This will require cooperationfrom operating department.

� Greasing of outer rail of curve should be done regularly. This willhelp in reducing the side wear of rails.

� Providing two meter long check rail at SRJ of turnout will protectthe tongue rail from wear.

� Ensuring rubber pads under the crossing will protect the crossingfrom breakage.

� Improving the ballast cushion in turnout portion, especially underthe crossing, will provide elasticity to the track and hence protectthe crossing and sleepers from damage.

� Providing gapless frozen joints at either end of crossing willsubstantially reduce the impact load.

� Eliminating the vertical and lateral misalignment at crossingswill prevent unnecessary wear of rail components and loss oftrack parameters.

� Pasting of rubber pad on the sleeper with epoxy or similar glueto prevent it from dislocation.

� Track at level crossings should be deep screened at a reducedinterval to avoid caked cushion under the sleeper. This will helpin preventing groove formation at the rail seat. Alternately, spacingof sleepers at LCs may also be reduced.

� Formation treatment should be planned at locations of weakformation.

� Wide cess at correct depth should be maintained for effectivedrainage and strengthening of formation.

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� Zero missing fitting should be maintained.

� Frequency of machine tamping at weak formation patches shouldbe increased. This will keep the track parameters fromdeteriorating and hence, will avoid unnecessary vehicular forceson track.

6.0 ConclusionHigher axle loading is a necessary evil. Its ill effects can not betotally eliminated but can definitely be reduced through sustainedmaintenance efforts. Again, these maintenance efforts should not bethe responsibility of any one department. A better track will requirebetter traffic blocks and better rolling stock free from flats and othertyre defects. A multi-disciplinary coordination comprising ofEngineering, Operating and Mechanical is essential to achieve this.Higher traffic will require higher maintenance efforts and betterplanning. System of corridor blocks should be strictly adhered to.Systematic traffic blocks help in keeping the productivity and moraleof field staff high. A motivated army is sure to win the battle.

References

i. Indian Railway Permanent Way Manual

ii. Section register of PWIs of KTE-BIN section

* * *

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Experience of Heavier Axle Load Operations & theMaintenance Strategies Adopted by South

Western Railway for CC+8+2 Axle Load Operations

D. G. Diwate*,Vijay Agrawal**,

P. Shameer Basha***

* Principal Chief Engineer/SWR** Chief Track Engineer/SWR*** Dy.Chief Engineer/Track/SWR

Synopsis: India, emerging as a leader among BRIC countries (Brazil,Russia, India & China), depends heavily on Indian Railways for itstransportation needs. The freight loading target of 890 Million Tonnefor the current year warrants successful operation of higher axle loadtrains. The dual role of Indian Railways as a freight carrier and serviceprovider to the teaming millions makes it mandatory to optimize/over-exploit the potential of its assets. The diffident beginning madein introducing CC+8+2 axle loads on the existing tracks has certainlyresulted in 10% growth of traffic without any major inputs. Theexperience gained in operating higher axle loads has been mostlyencouraging and been instrumental in moulding the P.way Engineersto be creative in their maintenance practices.

This paper will discuss various issues related to the performance oftrack components under CC+8+2T operation. viz., a) formation, b)ballast, c) sleepers, d) rails & e) track fittings etc.,

Special emphasis has been given to the points & crossings andsharp curves. Similarly the measures taken to monitor health andperformance of bridges are discussed. Also, the steps taken to curbover loading of wagons are brought out.

1.0 Introduction :Railway Board have approved running of CC+8+2T loaded BOXN andBOXN HS wagons for iron/other routes on identified routes as a PilotProject in May 2005. With this decision, the axle load has beenincreased to 22.9 MT from 20.32 MT. The permitted overload is 8 MTper wagon with the loading tolerance of 2 MT per wagon.

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Vasco-Hospet-Guntakal-Renigunta-Chennai is one of the 16 identifiedroutes of Indian Railways. The Pilot Project was introduced for aperiod of one year, which has been extended from time to time andas per the Board’s letter of August 2009 the currency of the projecthas been extended up to 30-06-2010. As per this letter, 9 additionalroutes have been identified for running freight trains with loaded up toCC+8+2.

CC+8+2 freight trains are being run on S.W.Railway since May 2005on the following routes:

1) Bellary – Hospet – Hubli – Londa – Vasco

2) Torangallu – Ranjitpura

3) Hospet – Swamihalli

The pre-conditions for running CC+8+2 trains are

1) Recording the loading spectrum actually passing over thetrack and bridges by means of “WHEEL IMPACT LOADDETECTOR” (WILD)

2) Limiting the speed of freight trains to 60 kmph, in case of 90R track only 30 kmph.

3) Introducing USFD techniques to detect RCF (Rolling ContactFatigue).

4) Evaluation and analysis of bridges with a view to imposespeed restrictions based on safety consideration.

5) Instrumentation of bridges for measuring settlement offoundations, tilting of piers/abutments, deflections andstresses at critical points and to access the balance life ofbridges.

2.0 Experience Gained:Various issues regarding performance of P.way under CC+8+2 freightoperations are brought out below:

a) Formation : The route identified for running increased axle loadhas been laid in early 20th century and well consolidated except forshort stretches of length 40 km. on Hubli–Hospet section.

In order to strengthen the formation, the following steps are taken.

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� Making up of cess as per standard cross section.

� Providing wider cess (4.5 m) and sub bank wherever the bankheight is more than 4.0 m

� Sand pouring in identified weak formation stretches. (Photosare enclosed)

� Laying geo-grid below ballast along with deep screening withBallast Cleaning Machine. So far 4 kms of track has beenstrengthened.

� Reducing the Super elevation by 5 mm on curves located onbad banks.

Photos of Sand Pouring

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b) Ballast : The required ballast cushion of 250 mm. (minimum of100 m. clean) is already available in the entire stretch. However,

Contamination of Ballast

the rate of contamination of ballast due to the iron ore droppingsfrom wagons, especially in the yard approaches, points & crossingszone, and increased scabbing of rails has been a major concern. Itis found that deep screening of such locations at five years intervel isessentially required to ensure better track geometry and to containweld failures/rail fractures.

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c) Sleepers : Concrete Sleepers are designed against bending failurebut heavier axle loads are causing problems due to rail seat abrasion.The identified routes have been laid with 1540 sleeper density andthe sleeper density is being increased to 1660 in planned manner inorder to run 25T axle loads.

i) Groove Formation Under Rail Seat: The present design ofsleeper is found adequate on straight and up to 50 curves.However, it is seen that the increased axle load is resulting intoformation of perceptible grooves (up to 2 mm. deep) under therail seat on sharp curves of more than 50 curvatures on Londa–Castlerock–Kulem section. This phenomenon of grooveformation is predominantly on sleepers manufactured and laidin 1994 during gauge conversion. This is resulting into loss oftoe load and resultant disturbance to track geometry due toloose packing.

ii) Damage to Sleeper Insert : The higher lateral thrust due tohigher axle load on curves shaper than 50 is resulting in breakageof sleepers and working out of insert grip length.

Sleepers with groove formation under Rail seat

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d) Rails:

i) Rail Wear : The increased axle load is resulting in comparativelyadditional vertical as well as lateral forces. The effect of increasedaxle loads is causing excessive wear of rail on sharp curves morethan 5o at the rate of 3 to 4mm in a year.

It is noticed in the heavily graded (1 in 37) ghat section of Castlerock-Kulem, 60 kg. 90 UTS rails are wearing very fast. Rail Renewal hasbecome necessary after passage of 160/170 GMT against stipulatedrail life of 800 GMT. Inter-changing of rails at a frequency of everythree years has been done and it is observed that the flow of metal isnoticed on inner rail.

Rail wear data collected for the last three years in the Hubli-Londasection is as below :

Curve Bet. Kms Bet. Degree Rail wear in mmNo stations of curve

2006 2007 2008 2009

12 536/300-537/00 TVG-NAG 3.5/5.76 3 4 7 2

27 544/800-545/400 NAG-DEV 3.31 2 3 5 7

31 546/800-547/300 DEV Yard 4.48 3 6 9 2

50 558/600-558/950 LD Yard 3.35 3 6 9 2

It is worth noting that the wear had been very excessive at isolatedlocations on the ghat section within two years, especially on theouter rail of sharp curves of 7 degree and above. The lateral wearmeasured was 11 mm and the vertical wear was 3 mm within twoyears of laying in the track at Km 39/100-200.

Rail lubrication at regular intervals is aiding in controlling the railwear. To ensure regular lubrication of gauge face, wheel actuatedlubricators are being procured for installing in the Castlerock-KulemGhat section.

ii) USFD Testing : Increased axle loading, particularly on 90 UTSrails, results in the phenomenon “Rolling Contact Fatigue (RCF)”.Rail head shape is critical for safe running of rails. Rail wear alsoaffects the contact area and contact stresses due to reduction in the

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cross-section. On CC+8+2 route, an increase in weld failure hasbeen noticed in the last two years. The comparative analysis ofUSFD results for the last four years is given below. From the data itis seen that there is an increase in gauge face corner defects. Jogglefish plating of the thermit welds on the outer rail of the curves hasbeen completed fully on all identified joints (15,894 nos.).

Year Normal Testing GFC Testing in 2005-06

Length No of IMR Length No of IMRtested IMR defect tested IMR defect(km.) defects per Km (km.) defects per Km

2005-06 1179.75 15 1.27% 519.10 06 1.16%

2006.07 1282.00 11 0.85% 732.80 01 0.13%

2007-08 1176.70 04 0.33% 827.70 01 0.12%

2008-09 1012.40 03 0.29% 1012.40 09 0.89%

2009-10 636.4 04 0.63% 636.4 17 2.67%

Rail/Weld failure data collected for the last three years in the Bellary-Vasco section is enclosed as below:

Sr.No Item 2005-06 2006-07 2007-08 2008-09 2009-10 (uptoSep’09)

01 Rail 09 12 16 21 08Fracture

02 Weld 77 70 48 56 33 Failure

From the above table, it could be seen that there is a drop in the weldfailures during the year 2007-08.The reduction is mainly due to theRail renewals carried out. However, Weld failures are on increasingfrom 2007-08 onwards.

e) Track Fittings:

i) Elastic Rail Clip : Toe load exerted by the ERC is getting reduceddue to a) Rail Seat Wear of the concrete sleeper and b) crushing ofGRS pad. The reduced toe load is resulting in creep in heavily graded

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sections. This is also resulting in increased maintenance effort interms of SEJ gap adjustment, de-stressing, etc. Hence, there is aneed to design higher toe load ERCs for CC+8+2 routes.

ii) Grooved Rubber Sole Plate : The performance of GRS pads,especially on CC+8+2 routes, is very poor as deterioration startsafter passage of 30 to 35 GMT and becomes totally non-functionalafter 65 GMT (2 years on S.W.Railway).

Procurement of GRS Pad based on revised and improvedspecifications needs to be taken up so as to replace the crushedrubber pads as part of Through Fitting Renewal. Strict quality controlwill be helpful in achieving better performance.

iii) GFN Liners : The increased lateral thrust due to CC+8+2operations are resulting into breakage of GFN liners, particularly atleg portion. The leg thickness of liner needs to be increased tocounter higher lateral thrust under dynamic conditions. Photos ofthe broken GFN liners (after a service period of six months on outerrails) are given below.

Few photos depicting the damage to GFN liners on account ofincreased lateral thrust are given below.

Damaged GFN Liners

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3.0 Special Track Layout :

i) Turnouts : Points and crossings have always been the weakestpart of the track, even in normal train operations. With the introductionof CC+8+2 operations, Turnouts are proving to be of major concerndue to the excessive wear and tear of tongue rail and Xing.

Switches: The rate of wear of tongue rail is very fast, especially forthe turnouts located on curves compared to normal axle loadoperations. To overcome this problem, short check-rails have beenprovided near toe of switch at all such turnouts. New tongue rail isserving for only one year and re-conditioned tongue rail is servingonly three months.

Anticipating the likely failures of conventional switches, Railway Boardhas planned phased introduction of Thick web switches on the heavyaxle load routes and Group ‘A’ routes. Procurement is in the process.

CMS Crossing: CC+8+2 operations are resulting in heavy wear onCMS crossing. The wear recorded on new CMS crossing is 2 mm.approximately for every quarter. Re-conditioned CMS crossing usingconventional method is serving only 6 to 8 months. However, theRobotic re-conditioning of CMS crossing is giving better service life.

The performance of CMS crossing with Robotic re-conditioning isfound better. Hence, Railway Board should consider introducing ofRobotic re-conditioning as standard practice for CMS crossing aswell as switches.

Photos showing the robotic re-conditioning of CMS Crossing areshown below.

Robotic Reconditioning Of CMS Crossing

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ii) Glued Joints : Glued insulated joints have generally giving aservice life of 5 to 7 years. From the pattern of glued joint failure, nodirect correlation could be done with running of CC+8+2.Statisticsshowing the failures recorded in one SE/P.Way jurisdiction are givenbelow.

Sl.No Item 2004-05 2005-06 2006-07 2007-08 2008-09

1. Glued 05 03 08 0 25Joint Failure

Due to the limited data availability about the age of the Glued joint,no direct correlation to Higher axle load and the failure could beattributed.

4.0 Monitoring Overloading of WagonsOverloading of wagons, particularly with iron ore has been of greatconcern to P.way engineers due to the adverse effect on Track andbridges. This used to be a major contributor to weld failures. The oldmethod of Weight-Volume ratio to decide the loading level for wagonswas very primitive and highly subjective. Engineering department wascarrying out surprise checks/ambush checks of the loaded iron orerakes for detecting overloading and forcing either unloading of excessweight or permitting movement of rakes at restricted speeds.

CC+8+2 operations made it very crucial to check the overloading ofwagons as the increased wheel forces on account of permitted higherloads and prohibited overloading will result in premature asset failures.In the new scenario, the prevalent method of Overload checks interms of Weight-Volume ratio was found to be ineffective and hencesetting up of In-motion Weigh Bridges has been planned.

In this regard, Board has issued guidelines for installation of weighbridges and WILD on 09.05.06 vide letter No.2005/CE-II/TSM Pt.and started operation of CC+8+2 T and CC+6+2 T freight train from15.05.06 (as per Commercial Circular 41 of 2006). Accordingly, sevenweigh bridges have been installed on S.W.Railway at the followinglocations:

1) Bellary ( Hospet-Guntakal)2) Bannihatti ( Toranagallu-Ranjitpura)3) Ginegere ( Hospet-Hubli)4) Tungabadra dam ( Hospet-Swamihalli)5) Dharwad ( Hubli-Londa)

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6) Sanvordem (Londa-Vasco)7) Saslu ( Hubli-Arsikere)

Due to the above weigh bridges, the extent of overloading has beencontrolled. A special cell has been commissioned at Zonal Railwaylevel to monitor the overloading and a monthly report is being sent toRailway Board.

Similarly, to record the loading spectrum actually passing over thetrack, Wheel Impact Load Detector (WILD) has been installed atkm.131/0-1 between Ginigera-Munirabad stations on Bellary-Vascosection by Mechanical Department of S.W.Railway. WILD is expectedto measure Maximum dynamic Load for loaded wagon and ImpactLoad factor for Empty wagon.

This installation is having teething troubles and yet to be issued withProving Test Certificate (PTC) by the division.

A sample report generated by the WILD is given below.

Wild Report For Hospet (HPT)DATE:2009-12-01 TIME:10:09:10 RUN No.:01122009100910 TRAIN DIRECTION:Up

SUMMARISED INFORMATION

TRAIN INFORMATION:-

Total Axles : 252

Average Speed of Train(kmph) : 62.6582

Total Number of Defective Wheels Recorded: 2

Engine =2 Coach / Wagon (8 Wheeler) =60 Tanker (4 Wheeler) =0 Brake Van(4 Wheeler) = 0

Defective Wheel Report

Date:2009-12-01 Time:10:09:10 Run No.: 01122009100910 Train Direction:Up

Wagon / Left Rail Right Rail

Serial No. Coach / Axle No. Maximum Maximum

of Position of Left Rail Dnamic Right Rail Dynamic

Alarm Defective from Wagon/ Load Impact/ Impact Impact

SL Level Axle Engine Tanker Factor Load (t) Factor Wheel (t)

1 * 27 4 3 - - 2.03 14.08

2 * 70 15 2 - - 2.54 15.87

Notes: 1:Maintenance Alarm Level (*) : 2.0 < = ILF < 4.5

2:Critical Alarm Level (**) : 4.5 < ILF or WA > 35T

5.0 Monitoring Health of The Bridges : With the introduction ofCC+8+2t operations, bridges are being inspected and their health isbeing monitored closely through regular quarterly inspections. Thedetails are given below.

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5.1 No of Bridge Identified for Inspection :

i. Important - 1

ii. Major - 44

iii. Arch - 4

iv. Others - 597

5.2 Details of Major Deficiency Noticed:

(i) In bearings - NIL

(ii) In super structures - NIL

(iii) In substructures - NIL

(iv ) Any other - NIL

5.3 Status of Instrumentation of Bridges:

i) In Phase I :

Sl.No Bridge No. Bridge Name Scope of work Current statusDetails of

Agency

Instrumentation in allthe bridges has beencompleted. Report ofall the five bridgeshave been receivedwhich indicates that allbridges are safe for 25T axle load. Final reportof all bridges sent toRDSO Lucknow.

It includesinstrumentation ofselected Railwaybridges forassessing theirstatic/Dynamicbehaviour,development ofcomputationalmodels to assessthe currentcondition and todevelop the toolsfor systemidentification andresidual lifeassessment due toenhanced axleloads andlongitudinal loadson the bridges.

Indi

an I

nstit

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of s

cien

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Ban

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e

1. 128, LD -VSGSection, @km39/5-6

2. 20, UBL-HPTSection @ km.46/15-47/1

3. 139 A, BAY-GAD section,HPT yard.

4. 3, TNGL-BNHTsection, @ Km.1/0-1

5. 102, LD-VSGsection, @ km.34/14-15.

Span2x18.29 +4 x 7.62 m.(Arch.)

Span5 x 9.14mArch type

Span1x30.48 m(Open WebGrider)

Span2x 19.4 m(throughGrider)

Span2x27.43 m.(ThroughPlateGirder)

ii) In Phase II : Five bridges have been identified for instrumentationin phase II over SWR as below:

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Sl.No Bridge No. Bridge Name Scope of work Current statusDetails o f

Agency

1) First round ofinstrumentation of allbridges have beencompleted in April /May – 09.

2) The report of allfive bridges havebeen received andunder study at HQ.

3) Second round ofinstrumentation hasbeen conducted inNov & Dec 09.

It includesinstrumentation ofselected RailwayBridges forassessing theirstatic / Dynamicbehavior,development ofcomputationalmodels to assessthe currentcondition and todevelop the toolsfor systemidentification andresidual lifeassessment due toenhanced axleloads andlongitudinal loadson the bridge

M/S

Sha

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ssoc

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1. 47 LD - VSGin UBLDivision

2. 293 HAS -MAQ in MYSDivision

3. 184 HPT- BAYin UBLDivision

4. 497 HAS -MAQ in MYSDivision

5. 47 GDJ - SMLIin UBL Division

5 x 12.2ArchBridge

2x30.5UnderSlung

1x12.2Composite

4x45.7 + 8x 4.4OWG &PG

3x12.2PG

5.4 Restriction of Tractive Effort to 30t for Running of WDG4MUon Bridges.Further in this route the following bridges are having restrictionof tractive effort to 30t per loco for running of WDG4MU withCC+8+2 rakes. These bridges are also inspected regularly everyquarter and so far no adverse effect has been noticed.

Sl.No Bridge No. Location Between station1 3 1/1-2 TNGL-RNJP2 39 19/10-11 GDJ-SMLI3 47 24/7-25/1 GDJ-SMLI4 157 153/8-9 HPT-BAY5 184 167/9-168/0 HPT-BAY6 200 174/0-1 HPT-BAY7 204 174/10-11 HPT-BAY8 206 177/13-14 HPT-BAY9 240 194/8-9 HPT-BAY10 243 197/6-7 HPT-BAY

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6.0 Stalling / Scabbing Cases : Number of stalling cases hasalmost been brought down to zero by ensuring proper powering afterconducting number of trials on higher axle load route. The details ofstalling cases vis-à-vis no. of trains loaded with CC+8+2 t are givenbelow.

YEAR No of trains Run with Stalling cases CC+8+2

2005-06 4627 3

2006-07 6080 0

2007-08 5934 0

2008-09 4813 2

2009-10 3030 8

The stalling cases have been brought down to negligible percentageby powering the trains judiciously and counseling the driver’s suitably.However, the rise in stalling cases during the current year has beenattributed to extended monsoon on SW railway and the reiteration ofguide lines to loco driver to ask for banker to avoid wheel burns andscabbing of rails.

7.0 Conclusion: With the experience gained in running higher axle loads and theincreased demand of freight transport, it is possible to optimizeutilization of existing assets. However, higher axle load operationsdemand

� Real time reaction of field engineers in monitoring the healthof the P.Way and intelligent deployment of the track machines.

� Elimination of thermit welds as much as possible.

� Ultrasonic flaw detection need to be further improved so as toaccurately predict the asset performance.

� Close monitoring of maintenance inputs by introducing TMSon identified routes in addition to Pilot divisions will be veryessential.

� Use of In-motion Weigh Bridges to detect over loading.

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� Use of Wheel Impact Load Detector (WILD) to prevent passageof flat tyres and unevenly loaded wagons.

� Elimination/Reduction of rail joints on bridges to reducedynamic impact of bridges.

� Preventing over speeding of goods trains.

� Planning for need based renewals instead of GMT basedrenewals.

� Introduction of strict discipline in checking over loading andaction on results of WILD.

� Correct powering of trains loaded up to CC+8+2 and improvedenginemanship.

It is time to look forward for introducing 25 T and higher axle loads bysuitably strengthening the bridges and inducting rolling stock withbetter suspension.

* * *

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Effects of Enhanced Loading (CC+8+2) on theTrack & Rolling Stock on Chennai Division -

A Managerial Perspective for RU-AJJ-MAS Section

- S. K. Kulshrestha*

* DRM/MAS/Southern Railway

1.0 Introduction:1.1 The upward revision of loading targets by Railways requireoptimum utilization of rolling stock, path, etc. This requires finetuned coordination between various departments as with enormityof the issues, the results may not be forthcoming beyond certainlimits. The policy of bulk loading, end to end running, running of CCrakes and incremental loading have been adopted by Railway Boardapart from procurement of additional rolling stock and new lines.Each change in policy brings in a new change for the maintenanceengineers.

1.2 The revival of Railway, reported recently, is due to the incrementalloading. This decision has helped in achieving the targets with ease.However, they have cut the safety margins for maintenance and arelikely to threaten the safety and viability of the system. To analysethe impact of the incremental loading and the perils of few of thedecisions which have manifested as failures a torough analysis wasdone to suggest the course of action. The CC+8+2 routes havebeen analysed as it has the critical impact on the system.

Synopsis: The progressive adoption of enhanced loading of IndianRailways warrants analysis of the issues of maintenance, operationand the policies, the optimum utilization of the assets enhancingthe scope for earning the revenue without undue stress. In thepresent paper, a managerial approach to the failures in RU-AJJ-MAS section suggests changes in the policies to suit the local need.

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1.3 The Ports in and around Chennai are the links for the export ofiron ore and for receiving coal, fertilizers, etc. The linkages for thePort are to the power house and major industries. Railways handlesabout 50% of the commodities transacted at Port. The non-movement of the remaining traffic is attributed to space availabilityand poor progress of mechanizing, reduced maintenance of the railassets within the HOM area and the practices of HOM. The cost ofmovement by road is more than the Railways but due to ease andconvenience road ways has a considerable share of the same.Enhancing the share of Railways in moving the goods from Portprovides scope for additional revenue. With the overheads remainingthe same, profits rise up and can be used for the maintenance. Theenhanced loading has the effect of increase in carrying and therebyimproving the operating ratio. The extensive damages to RollingStock as well as Track can cost dearly in incremental loading thusproving counter productive.

1.4 The damages to Rolling Stock makes it unfit for loading anddamaged wagons are moved as empty along with loaded wagonreducing the earning and enhancing the expenditure.

1.5 The carrying capacity of BOXN wagon is 55 tons, the enhancedload is 8 tons per wagon which is a 14.5% increase. If the wagonsrunning as empty in a rake of 59 exceeds 8, the benefits ofincremental loading will be completely nullified. In certain casesdue to exigencies, these wagons also gets detached and compositionof rake gets reduced. Running trains with short of compo/emptywagon subject Rolling Stock and Track to higher stress withoutextra revenue but with extra expenditure on empty haulage andrepairs. The details of various types of wagons are tabulated below:

S. Type Axle Load Tare CC Whether No upgraded

1 BOXN 20.32 23.2 58.08 Yes

2 BOXN HS 22.82 23.2 68.08 Yes

3 BOXN HA 22.1 23.17 65.23 Yes

4 BOXN HL 22.9 20.6 71 Yes

5 BOXN EL 25 23.1 76.9 Yes

6 BOXN LW 20.3 18.26 63.02 -

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1.6 The policy of Railway Board communicated in their CommercialCircular has commodity specific monsoon period to be adoptedthroughout India. During monsoon period, the loading is restricted toCC+6+2. The monsoon over India varies from region to region. Incertain regions particularly southern India, it can so happen that therewill be a loss of revenue due to reduced loading in a season wherethere are no rains. This in turn enhances the damage to RollingStock as well as Track with the continuing of enhanced loading evenduring rain. The part of the CC+8+2 route from HOM to RU, runningvia South Western Railway and South Central Railway upto Hospet,is a best representative for analysis.

Routes

CC+8+2 Vasco-HPT-RU-AJJ-VPY-HOMVPY-AIP,AIP-EPLS

CC+6+2 All other routes of Southern Railway

1.7 In the present paper, an earnest attempt is made to analysevarious aspects of maintenance and practices adopted for enhancedloading in a section with the effect on asset failures, to find theremedial measures. The loading being as under.

Originating Loading in tonnes (in ‘000s)

Period Target Actual2008-09 17,358 16,923

2009-10 (upto October ’09) 9,926 9,749

2.0 Track2.1 The track structure in RU-AJJ-MAS Upline was with 1540 sleeperdensity with 52Kg rails and 1660 sleeper density with 60 Kg railsduring 2006-07. Subsequently, except 10 Km all the stretches havebeen converted into 1660 sleeper density with 60 Kg rails.

2.2 CC+8+2 Routes In Chennai Division

Southern Railway has 631 Km under CC+8+2 Route.

(i) Renigunta (RU)-Arakkonam(AJJ)-Vysarpadi(VPY)-Attipattu(AIP) (For Ennore Port) and Chennai Beach (For ChennaiHarbour- HOM)-154 Km (134+20)

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(ii) Gudur (GDR) – Chennai Central (MAS) – 136 Km

(iii) Arakkonam (AJJ)-Mettur Dam (MDTM) and Jolarpettai(JTJ) – Somanayakanpatti (SKPT) – 317 Km (294 +23 ).This route has been recently nominated for CC+8+2 route,vide Rly. Boards’ Lr.No.2008/CE-II/TS/2 Dated 31-8-2009.

(iv) TOK-PNMB (Tokkur to Panambur) 24 Km

Out of total 631 Km in Southern Railway, Chennai Divisionalone has CC+8+2 route of 436 Km . The route (ii) and(iii) are recently included in CC+8+2. However, the route(i) RU-AJJ-VPY-AIP-HOM has been nominated forCC+8+2 as a Pilot Project since July’2006.

2.3 Monitoring Mechanism:To monitor the Permanent way assets due to the running of CC+8+2iron ore rakes, the Quarterly Inspection Report of ADENs is to besubmitted to HQrs through Division. The report involves the followingparameters:

(i) No. of CC+8+2 trains run during that Quarter

(ii) Safety – derailment of CC+8+2 train with cause

(iii) Track – Status of 90R rails ( Balance if any to be removed)

(iv) Track – Status of Rail / weld failure

(v) Track – Status of USFD testing involving no. of IMR andGFC (Gauge Face Corner) defects

(vi) Track – scabbing and wheel burn on rails

(vii) Track – Effects on turnouts involving wear on CMS Xings &crushing of rubber pads

(viii) Track – Effects on curves of more than 3 degree involvinglateral wear

(ix) Bridges – Important Bridges, Typical arch bridges andcertain no. of minor bridges have been selected and theinspection being done every 3 months to ascertain thebehaviour of bearings, superstructures and substructures

2.4 Impact on Track Assets:After the pilot study was introduced the following observations havebeen made with regard to the track on the section.

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(i) 2 locations scabbing of rails /wheel burn on rails haveoccurred within the very First year of running of CC+8+2trains, i.e, from July’06 to Sep’06.

(ii) The wear on curve outer rails is more in CC+8+2. Upto2mm vertical wear is found on 3 degree curve within 2years (The rail was laid during July’07; the measurementwas taken on April’09).

(iii) It is observed that wear at the crossings is more and G.R.Sole plates at CMS crossing requiring renewal once insix months. At the same time the CMS crossing requiresfrequent renewal

(iv) Wear is more on built up crossing requiring renewal oncein six months.

(v) Wear on outer tongue rails has increased

(vi) No. of OMS lateral peaks increased

(vii) Rubber pads are getting crushed frequently warrantingrenewal within 2 years.

(viii) Iron ore powder falls on shoulder contaminating the ballastwarranting shoulder ballast cleaning. Iron ore falling onrail table and getting crushed is causing pitted rail top.

(ix) The glued joints get severely battered due to Heavy axleloads and requires frequent attention and renewal.

(x) No. of Points and Crossings require frequent tamping.

(xi) However, there are no adverse effects on bridges in thisroute.

(xii) More USFD defects like OBS(W) and IMR were noticedin the old rails in the section. Even after renewing with 60Kg new rails, this problem is continuing. This can be seenfrom the table below:

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Abstract Of USFD Defects Yearwise In AJJ-MAS Up LineBetween Km.4/0-68/0

YEAR OBS OBS(W) IMR IMR(W) Total No.of Defects

2004-05 18 46 0 0 64

2005-06 8 59 2 0 69

2006-07 16 77 0 2 95

2007-08 9 67 2 0 78

2008-09 3 62 0 0 65

2009-10 20 45 5 2 72(upto Nov.2009)

1. CC+8+2 was introduced in July 2006.2. Interchanging of rails have been done during 2007-2008 thatresulted in lesser USFD defects.3. It is evident from the data shown above that the defect rate isin increasing trend after introduction of CC+8+2.

Abstract Of USFD Defects Yearwise In AJJ-MASUp Line Between Km.68/0-134/780

YEAR OBS OBS(W) IMR IMR(W) Total No.of Defects

2004-05 20 25 0 0 45

2005-06 10 28 1 1 40

2006-07 20 58 0 0 78

2007-08 15 67 0 0 82

2008-09 10 60 0 0 70

2009-10 19 44 1 1 65(upto Nov.2009)

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1. CC+8+2 was introduced in July 2006.2. Interchanging of rails have been done during 2007-2008 thatresulted in lesser USFD defects.3. It is evident from the data shown above that the defect rate isin increasing trend after introduction of CC+8+2.

(xiii) The details of renewals done is given below:

KMEngine Line Total Rail UTS Laid WorksRun FROM TO KM Section Year done

MAS-TRL UP 4/0 5/0 1.000 52 90 2008-09 CTR

AJJ-RU UP 69/450 71/450 2.000 60 90 2008-09 TRR

AJJ-RU UP 82/250 82/700 0.450 60 90 2007-08 CTR

AJJ-RU UP 82/900 87/500 4.600 60 90 2007-08 CTR

AJJ-RU UP 87/500 88/740 1.240 60 90 2007-08 CTR

AJJ-RU UP 88/840 95/240 6.400 60 90 2007-08 CTR

AJJ-RU UP 103/475 125/0 23.525 60 90 2007-08 CTR

AJJ-RU UP 125/0 133/600 8.600 60 90 2008-09 CTR

MAS-AJJ UP 8/100 8/600 0.500 60 90 2006-07 CTR

MAS-AJJ UP 8/600 9/940 1.340 60 90 2007-08 CTR

MAS-AJJ UP 10/40 11/600 1.200 60 90 2007-08 CTR

TOTAL 50.855KM

(xiv) It can be seen from the following table that RF/WF have increasedduring the initial stages of introduction of CC+8+2, i.e, during2006-07; subsequently failures have reduced due to large scalerenewal works, ie., about 51 Km of CTR works done in thisSection.

RU-AJJ AJJ-MAS TOTAL

Year RF WF RF WF RF WF Remarks

2003-04 52 68 63 60 115 128

2004-05 31 82 29 34 60 116

2005-06 20 91 16 23 36 114

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2006-07 25 108 16 21 41 129 *CC+8+2introduced

2007-08 9 49 11 36 20 85 $ Reduction

2008-09 8 48 11 27 19 75 in failure

2009-10 3 23 16 17 19 40 due to track(upto Nov renewals/09)

Note* CC+8+2 is having more impact on Weld failures.$ Reduction in failure is due to track renewals.

(xv) The TGI value is found to be deteriorating as can be seen fromthe following table: In MAS-AJJ Section, the TGI value isdecreasing due to CC+8+2 route as only 4.040 Km of CTR hasbeen done in this Section. However, in AJJ-RU Section, the TGI

value is increasing due to large scale CTR works done.

Comparative TGI Values for 7 years in CC+8+2 routes

YEAR MAS-AJJ AJJ-RU

2003-04 86.51 94.32

2004-05 90.82 83.91

2005-06 91.92 82.75

2006-07 96.81 87.96

2007-08 92.51 90.53

2008-09 96.45 98.27

2009-2010 95.53 98.11

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3.0 Availability and Damages to WagonThe enhanced loading increases the stress on structural members,couplers and suspension. This has increased the pace of deteriorationrequiring earlier attention than the scheduled attention. The numberof vehicle maturing for attention increased more than ten fold withrepairs such as body, CBC defects, wheel defects, spring renewal,elastomeric pad renewal, etc. Apart from increased duration forattention, the wagons awaiting attention have also increased. Theaverage wagons marked sick post-incremental loading have increasedconsiderably. The data pertaining to JTJ and TNPM depots isenclosed. Taking cognizance of such detention, Railway Board wentto the extent of directing Shops to give priority for unloadable repairsover the POH of wagons at Workshops and encouraged outsourcingof unloadable repairs to augment repair capacity. The increasedrepairs and detention have caused reduced availability of the wagon.The severity of this has damaged only the BOXN wagons. Thereduced availability of BOXN wagons coupled with the increasedloading targets have made the Railway to view seriously the damagescaused by unloading agencies and defer the maintenance schedules.While deferring the maintenance schedules will increase failure suchas hot axles, enhanced repair per wagon at Shops, etc will lead toreduced availability of wagons. The Railway will be in a vicious circle

20

08

-09

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giving a reduced output unless augmented by procurement of morewagons involving extra expenditure.

4.0 Speed of Trains:The speed of the goods trains have also undergone a downwardrevision with the introduction of CC+8+2 loading. The speed potentialof the train have been revised as below :

Type of Stock Speed for Speed forNormal loading Enhanced loading

BOXN 75 60

BOXN HS 100 60

4.1 The reduction of speed has reduced the kinetic energy availableto the train while hitting the gradient. Therefore, the need to maintainthe higher tractive effort while negotiating a gradient on account ofhigher load has increased to maintain the constant speed. Thishas the potential to increase stress on the track giving scope forfailures of the track.

5.0 Policy on Monsoon SeasonThe Railway Board in their various circulars have assumed acommodity specific uniform monsoon period for CC+8+2 rakes. Theloading of gypsum during 1st June to 31st August is restricted toCC+6 even in the CC+8 loads and loading of E, F and G grade coalis restricted to CC+6 from 1st July to 15th August whereas the monsoonin the Chennai Division is during October and extends upto middle ofJanuary. Therefore, during the period where restriction is imposedby Board, the Southern Railway can actually run trains to CC+8+2loading. Therefore, there is a loss of revenue for forgoing the loadingdue to instructions from Railway Board. The loss is quantified asunder

In terms of Wagons

Coal Steel coal Coke Total

Jul-Aug 2009 1722 6484 3201 11457

Total enhancedweight by 2 tons 22914 tons

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5.1 Similarly, during the monsoon at Chennai Division, the loadingis continued, with 751 number of CC+8+2 trains during Oct-Dec2008. These trains have potential to cause damages to track. Thelacunae in the policy can therefore cause enhanced damages totrack on one hand and also result in loss of revenue on the otherhand. The wagon defects such as flat tyre, defective suspension,etc have capability to transfer higher impact load to the track. It isrequired to quantify the impact load to isolate the wagons whichhave potential to cause damage.

Total No. of Trains run with CC+8+2 in MAS Division

Period No. of Period No. ofTrains Trains

April-June 2009 783 April-June 2008 809

July-Sept 2009 916 July-Sept 2008 622

Oct-Dec 2008 751

Jan-Mar 2009 1089

6.0 Equipments to Pre-warn Damages to TrackThe Railway Board has made provision of Wheel Impact LoadDetectors in the CC+8+2 routes. One such impact load detector isin the section from RU to AJJ near AJJ. This Wheel Impact LoadDetector (WILD) has identified 5 number of wagons since its inceptionand helped to detect the culprit wagons capable of causing damagesto track. If the Wheel Impact Load Detector is placed closer to RU,the damages caused by running wagons from RU to AJJ can beavoided. Therefore, it is required to relocate the WILD to RU. Similarly,the WILD is an improvised weighbridge with additional sensors andlogic. If all the weighbridges are converted into WILD, apart frommaking the weighment, it will also help in detecting the defects inwagon suspension and wheel which will eliminate the defects. Thecost of WILD and In-motion Weighbridges is as below :

Description Procurement Cost

In Motion 2009 Rs.14,96,000/-Weighbridge

Wheel Impact 2007 Rs.75,68,910/-Load Detector

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6.1 The location of the WILD can be rationalized such that theexposure of the track to the defective wagons is minimized.

7.0 Unloading TimeThe total load on the train has increased by 14.5%. The length of thetrain has also increased by a wagon or two. Yet the timing allowedfor unloading and loading have remained the same. Due to paucityof time, the wagons are generally seen with uneven loading andextensive damages due to mechanized unloading. This is furtheringthe damages to wagons and consequential damages to track.

8.0 Conclusion & Recommendations8.1 The policy of enhanced loading has provided a scenario wherethe loads in the wagons have increased by 14.5% and the maximumspeeds of the trains have come down by 20%. The wagon defectsdirectly attributable to increased loading have risen tenfold in most ofthe crucial parameters. The availability of wagon has come downdue to extensive detention and detachment of wagons awaiting repairsforcing Railways to augment capacity for attention by outsourcing.This has resulted in shortage of wagons. Therefore, Railways haveresorted to postponing maintenance schedules of wagons. Now,instructions have been received for postponing the POH of BOXN aswell as BCN wagons. As we need to continue with the CC+8+2loading, it is suggested that to contain the damage to the minimumby directed improvements in the rolling stock the policies should bemade conducive to enhanced loading. The following are suggestedwith regard to rolling stock:

(i) Outsourcing of on rake attention of damaged wagons.

(ii) Providing WILD for detecting wagon defects

(iii) Running of train with engine at both ends to avoid excessivecoupler force and removing the brake van so Guard cantravel in the loco in the rear.

(iv) Making a policy for rainy season or providing a temporarycover for wagon

(v) Provision of additional spring on wagon.

8.2 During the past Two and Half years, with the experience of dealingwith CC+8+2, it is understood that various track elements like Pointsand crossings, glued joints, rails on sharp curves have been badly

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affected. At the same time, the existing bridges withstand CC+8+2traffic without much maintenance problems. In fact, some of theBridges in this route (1 major bridge with PSC girders with span of 14Nos. x 20.5m and another major bridge with steel girders with aspan of 13 Nos. x 12.19m) have been tested with CC+8+2 rakes andInstrumentation was done with the help of IIT/Madras. It is found thatthe stresses are well within the permissible limits. Hence, the followingrecommendations are made with respect to track maintenance inCC+8+2 routes:

a) CMS Crossings may crack under heavy impact load andhence the GR pads need to be renewed within 2 years.

b) Greasing of outer rail curves having more than 3 degreecurvature to be done frequently to avoid wear.

c) Level crossings to be maintained with clear cushion toavoid rail/weld failure

d) Points and Crossings to be deep screened and tampedwith a frequency of one and half year.

e) Rubber pads and glued joints to be renewed frequently.

f) Shoulder ballast cleaning to be done to improve the drainage.

g) If old rail exists, frequent USFD testing of rails and weldsto be done.

h) Built up crossings in CC+8+2 route to be eliminated.

***

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Heavier Axle Load – Effect on P.Way &Reorganising Track Maintenance Strategies.

Amit Agarwal *Rajiv Kumar Tanwar**

M.Jayaprakash Reddy***

*Sr.DEN/South/GTL/SCR**DEN/Bridges/GTL/SCR***DEN/West/GNT/SCR

Synopsis: Indian Railways in an effort to increase its transport capacityhave taken a bold decision to run trains with higher axle load on ironroutes and some other specified routes. Such a decision no doubthas made a financial gain for Indian Railways but it has introduced alot of implications, which requires to be studied and addressed. Thepaper deals about the effects of running higher axle loads on trackbased on experience of running CC+8+2T load on Guntakal & Gunturdivision for last 4 years and the sensitive issue of management andmechanized track maintenance which are the main issues if IndianRailways have to maintain the track efficiently and economically torun heavier axle load trains.

1.0 Recent Development of Adopting Heavy Axle Loads onIndian Railways :The beginning has been made in the year 2005-06 by taking up thepilot project wherein axle load upto 22.82 ton against existing 20.3ton have been permitted on existing BOXN wagons and on designatedroutes (22 routes over seven Railways). With the experience gainedfrom this pilot project for one year ( 15th May 2005 to 14th May 2006),the running of 22.82 ton axle load has been universalized in most ofthe freight intensive routes of Indian Railways. Now Indian Railwaysis gearing up to move one step further in this direction i.e., running oftrains with axle load of 25 ton in near future on selected routes.

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2.0 World Scenario of Heavy Axle Loads:

Railways Axle Load

BHP Biliton, Australia 38.0

Canadian Pacific Railways 33.0

Russian Railways 23.5

Norfolk Southern Railways( USA) 33 – 36

Chinese Railways 25

IHHA recommendations 30 – 34

It is evident that heavy axle loads ranging from 30 to 40 tonnes arerunning in America, Australia and other advanced railways. But thereis major difference in scenario prevailing on Indian Railways unlikeworld railways, where heavy freight trains runs on dedicated routes.the same infrastructure has to carry both freight and passenger trafficon Indian Railways.

3.0 Heavy Axle Loads on Guntakal & Guntur Divison of SCR:Railway Board has permitted operation of BOX’N’ wagons loads upto CC+8+2 on identified iron ore routes as pilot project vide RailwayBoard lr No.2003/CE-II/TS/5/Vol I dt 02/05/2005. Guntakal Divisionbeing the fore most routes in transporting iron ores on this Railway,the stretch between Bellary-Guntakal (SL) and Guntakal-Renigunta(UP/SL) was identified for the pilot project and from 15/05/05 theheavy axle load vehicles were introduced with a speed restriction of60 Kmph.

The higher axle loads of CC+8+2 were also permitted betweenGuntakal-Dhone-Nandyal stretch on GTL division and Nandyal-Guntursection on GNT division, and trains started running with higher loadsfrom Feb’06 onwards.

In JAN’08 it was further extended to PDL-GY-DMM section. At thesame time all other routes of GTL Division were universalized forCC+6+2 loading.

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4.0 Track Response Under Heavy Axle LoadAs heavy load moves over a rail, the track is compressed temporarilyor deflects and then rejoins after the load has been removed. Thisvertical deflection is the best indicator of the track strength, life andquality. Excessive deflection results in differential movement andwear of track components. Research and guidelines of Railwaysthrough out the world reveals maximum deflection of 6mm for heavytrack with firm sub-grade. Track which deflects more than 10mm willdeteriorate quickly under axle loads.

The track structure must simultaneously satisfy requirement forstiffness ( i.e. resistance to deflection and flexibility). Track qualityis measured by track modules, which is a overall measure of supportunderneath rail. Track modules affected by ballast depth and qualityand subgrade characteristics in which PSC sleepers and elasticfastenings are vital component to be maintained properly.

5.0 Experience of Running CC+8+2T Loads (22.82T) Axle LoadSince May 2005 on Guntakal & Guntur Division i.e. Bellary-Guntakal - Renigunta and Guntakal –Nandyal-Guntur Section.5.1 Ballast and Screening:

The support beneath the rails is critical factor for effective transfer ofloads. The function of ballast is to transfer and distribute the loadfrom sleeper to larger area of formation, to provide elasticity andresilience etc., to track. Increasing axle load will require increaseddepth of ballast cushion.

The existing ballast cushion on these route is ranging from 200mmto 300mm. Efforts have been taken to complete the deep screeningof track as per norms and ballast has been dumped into the track asrequired. The deep screening of GTL –NDL section had completed in2007-08 and 2008-09 duly using 2 BCM’S and at present there is nooverdue location on these routes.

However, due to constant dropping of iron-ore particles which wereloaded beyond the door level and due to improper closure of wagondoors, the ballast gets contaminated and is becoming solid bed likerock duly affecting drainage and running quality. This have beennoticed especially at the approaches of major yards like Dhone, Gooty,Nandlure,and Renigunta. The problem is more acute in yards whereloading is also being done. In Hagri which is iron ore loading point

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the problem of poor drainage is noticed during rainy season.

With the result of this, it is necessary to carryout shoulder ballastcleaning once in 2 years and deep screening once in 7 years.

5.2 Effects on Sleeper and Fittings:(i) Deficient packing at joggled fish plated location

It is observed that after running of CC+8+2T load, the increasedgeneration of USFD defects due to OBS/Cupped Welds has resultedin increased population of joggled fish plated welds. The presentfittings in use at these joggled fish plated joints ( i.e. ERC mark.III inreverse condition/J clip) makes the sleeper vulnerable to more impactbecause of lesser toe load and propensity of development of gapbetween rail bottom and sleeper. In fact, this has further deterioratedthe situation due to crushing of rubber pads on welded joint locations.

(ii) Extra stress on sleeper fastenings near weld locations Due toinappropriate dimensional tolerances formed during initial weldingstage and during process of maintenance (formation of cupped welds),the rubber pad gets crushed near the weld locations require frequentrenewals. In fact in this railway a practice is made to keep 2 rubberpads at each such welded joints, the frequency of renewals at theselocations approximately once in 2 years against the normal renewals.

(iii) Effect due to iron ore droppings

(a) Due to falling of iron ore particles on the flanges of rails,liners and ERCs, the rails and fittings are getting morecorrosion compared to earlier resulting in greasing to ERCsand painting of rails to be done at increased frequency asthat of corrosion prone area.

(b) Due to continuous iron ore droppings in some of thestretches the ballast is becoming caked up and thereforeaffecting the drainage as well as quality of tamping. Thisin long run will result in more frequent shallow screening/deep screening. Consequently, as a result of reducedresilience the additional stresses are likely on sleeper/fittings.The life of fittings is getting reduced in such location.

(iv) Reduced life of rubber pads in generalThe experience of last 4 years has shown that other than the locationsdiscussed vide i, ii & iii above, the available design of elasticfastenings are surviving without abnormal deterioration except rubber

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pads. In fact, at several TFR locations ( other than corrosion pronearea), it is noticed that lot of metal liners and ERCs are found tohave further residual life whereas the condition of rubber pad aredeteriorated. With the increase in loading patterns, thisphenomena of crushing of rubber pads will be more and require theirfrequent renewal. To meet the variations in life cycle of the differentfittings, it is required to adopt thick/improved rubber pads. Further,it is recommended that Through Pad Renewals on such heavieraxle routes in between TFR cycle for maintaining the trackparameters may be required.

5.3 Rails:Due to dropping of iron-ore particles on flanges of rails, the corrosionin 90UTS rails are increasing compared to earlier, necessitatingpainting of rails at increased frequency as that of corrosion pronearea, though the stretch is in non-corrosive area.

Formation of small spots on top of rail head: Due to iron ore lumpsdropping on top of the rail and getting crushed under moving wheel,formation of small spots upto 2mm size noticed which are affectingthe running qualities of track at a later stage.

(i) Rail/Weld Failures: The comparative statement of Rail/Weldfailure for section running CC+8+2 loads for last four years are asunder:

Rail/weld Failure in CC + 8 + 2 route BAY - GTL (DN), GTL-RU (UP/SL)& GTL - NDL (SL) & NDL - GNT (Sl)

S Section 2006-07 2007-08 2008-09 2009-10No. (upto Sep.09)

RAIL WELD RAIL WELD RAIL WELD RAIL WELD

1. BAY-GTL 2 31 1 11 - 5 - 1(DN)

2. GTL-RU 2 109 1 66 - 43 - 10(UP/SL)

3. GTL-NDL 1 19 1 36 3 67 1 43(SL)

4. NDL-GNT 1 130 0 232 0 279 1 24(SL)

TOTAL 6 289 3 345 3 400 2 78

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••••• In BAY - GTL Section :There was weld failure in 2005-06 mainlyon account of old 52 kg72 UTS rails which were already carriedenough GMT. The same had come down considerably in 07-08and further in 2008-09 on completion of 40 KM deep screeningby BCM and renewal of old track with CTR(P) 60 Kg.

••••• In GTL-RU section, there is a phased reduction in rail/weldfailures in GTL- RU section mainly due to CTR/TRR of about 100Kms with 60 kg rail and deep screening of about 60kms PSCtrack which was overdue. The track works like deep screeningand TFR have lot of impact on reducing of weld failures whichcan be noticed in km.233 between MMPL and VNM where 7failures have taken place in 06-07 and only one failure in 07-08after deep screening and TFR.

••••• In GTL-NDL & NDL-GNT section, the failures have increasedin this section from 151 in 06-07, 269 in 07-08 to 349 in 08-09.Even in this current year also there are 69 failures till SEP’09.This section is having 52 kg rails of 1996-97 laid during gaugeconversion. The population of skv welds are more since freerails were welded and made LWR.

••••• This section opened with 4 GMT traffic in 1997 and now GMT is32, therefore the more weld failures may be due to increaseGMT also. However efforts are being made to reduce it by carryingout TFR and Destrssing during last 2 months, and there isconsiderable reduction in Weld failures in last one month in GTL-NDL section.

(ii) Curves: Wear on outer rails in curves have increased,necessitating greasing of curves once in a week/twice a weekdepending upon the sharpness. The wear on sharper curves in GTL-NDL section has considerably increased in the last 2 years of runningof CC+8+2 in block section PNM- BMH of GTL-NDL Sction, which ishaving 1in 83 rising gradient with 12 curves having maximum degreeup to 6, both lateral and vertical wear crossed the permissible limits.Here 14.5 KM of CTR got sanctioned on that account in 2007-08 and2008-09. further 11 KM CTR(P) is proposed in PWP-2010-11 for MYL-DHNE section on wear account.

Similarly in GNT division on a 5.7 degree curve laid with 52kg 90 UTSrail on PSC 5 sleepers at Km.217/4-218/0 and at Km.171/8 – 172/2

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with fairly uniform versine throughout its length, lateral wear on outerrail has reached 10mm and rails renewed on 3/2009 despite ofprovision of check rail and hand greasing of gauge face of the railtwice a week. The wear was 3mm during 6/2005 and the cumulativeGMT carried by the rail is just 35% of estimated 525 GMT. The spurtof wear attributable to positive angle of attack of wheel flangeaggravated by higher axle load in turn higher flange force.

However efforts are being made to do regular curve greasing to reducewear. Use of automatic greasing machine may help in reducing themanpower and provides uniform application of grease. Manual systemof greasing besides being irregular and non uniform, involves safetyrisk to trackmen deployed for greasing on sharp curves due to visibilityproblems. There is need to evolve an efficient automatic greasingsystem. Available systems were tried but not found to be successfulon long term basis. Providing wear resistant rails on curves orreducing the frequency of replacement of outer rails of curve to 150GMT for 52 kg 90 UTS rails may also provide relief.

(iii) Stalling : On steep rising gradients, more number of stallingcases is noticed, especially in rainy season where the axle load isgetting increased due to water content. The comparative details ofstalling are given below:

Section 06-07 07-08 08-09 09-10 (Up to

SEP’09)

BAY-GTL 0 1 0 0

GTL-RU 9 3 0 0

GTL-DHNE-NDL 3 4 0 0

Due to strict vigilance on over loading and right powering, stallinghas been reduced. This can be fully avoided if additional tractivepower is provided between HX-NRE stations especially during rainyseason.

(iv) Scabbing : Scabbing is mostly found on rising gradient, signalapproaches and where trains speed is restricted due to caution orderor other reasons. The comparative details of scabbing are givenbelow:

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Section 06-07 07-08 08-09 09-10

(Up to SEP’09)

BAY-GTL 0 0 1 0

GTL-RU 3 1 1 0

GTL-DHNE-NDL 13 3 0 4

In GTL-RU section the scabbing mostly has occurred in rising gradeand in combination with insufficient tractive power at signal approachesand at caution order spots where driver could not regulate the speedin time. As regards GTL-NDL section they have mostly occurred inGhat section where continuous rising gradient exists inuncompensated sharp curves in between PNM-KEF and in raisinggradient between GTL-MKR stations. This can also be avoided byhaving sufficient tractive power and good engineman ship.

5.4 Points and Crossings:This being the weakest link, requires frequent attention. Due toincreased hammering at all free joints including crossing joints, thepacking gets badly disturbed and alignment defects noticed, thefittings getting crushed/worn out/ dropped, also running quality gettingdeteriorated, necessitating packing with Unimat mandatory once in6 months. Picking up slacks is being attended with off-track tampersas and when necessary. The GR pads of complete turnout are to bechanged once in 4 years & under points and crossings once in ayear with 10mm GR pads with horns. GFN liners are to be changedonce in 3 yrs and especially outer liners on outer rails once in a yearwhere side wear takes place and GFN liners are getting ejected.

Due to heavier axle load, the trains while negotiating turn out inducemore stresses on outer rail due to which outer side bearing plates,rail screws are getting wornout frequently specially at sleeper no14,15,16 in 1 in 8.5 turnout plate screws are bending/shearing. Atother locations life of plate screw is 5 years but at these 3 sleeperslocation because of more thrust due to heavy axle load trains fromturnout side, life of plate screws are getting reduced to 2 years only.The design of these sleeper fitting requires some improvement in theform of provision of MCI insert and ERC at the end of slide chairs toprovide more lateral stability as available at sleeper no 3,4,5.

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5.4.1 Wear of Turn Out Side Tongue Rails:••••• On fan shaped lay outs laid during 1995-96 during gaugeconversion between GID-NDL, turn out side tongue rails were takenup for reconditioning on account of knife edge formation as 1st

occasion during 09/2005 after a initial service of 10 years and majorityof the tongue rails again reconditioned during 11/2006 within a shortspan of about 1 year for the same reason.

••••• Reconditioned Tongue rails of 52kg 1 in 12 (Point No.28B, 25B,24B/NDL) found to sustain only for a period of 7 or 8 months effectivelyi.e. for a life of 15 GMT as against anticipated life of 30 GMT.

5.4.2 Chipping of CMS Crossings Nose:Due to wheels jumping from wing rail to crossing and vice versa, thewear of crossing nose & wing rail have considerably increased withchipping/breakage of crossing noses, specially at locations wherere-conditioning have been done number of times and where resilienceis not available due to hard bed. Comparative statement showingcrossing nose chipped off is given below:

Section 06-07 07-08 08-09 09-10 (up to

SEP,09)

BAY-GTL 10 4 4 2

GTL-RU 16 5 6 3

GTL-DHNE-NDL 27 10 10 5

As regards to GTL-NDL section the increase in crossing nose chippedoff is mainly due to initial stage of introduction. Further heavy goodstraffic started running only from Feb-06 onwards. All the points andcrossings were laid in 1997 during gauge conversion and since mostlypassenger traffic were running they were not reconditioned. The Goodstrains coming from GNT side are not being weighed any where andloading particulars were not available for detailed analysis. Hence,over loading beyond CC+8+2 can not be ruled out as one of thepossible reason. As this stretch is in ghat section with continuousgradient (condoned) slight over loading also causes heavy damageto track components specially points and crossings. All effort likedeep screening, packing, ensuring fittings are being done now toensure safety.

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5.4.3 Wear of CMS Crossings:Newly laid 52kg CMS crossings is fast wearing to an extent of 4-5mm (6-2mm) on Nose and 3mm on wing rails within a period of 12to 18 months.

5.4.3.1 Details of Laying and Wear of CMS Crossings is as under:

- Similarly reconditioned CMS crossings attain wear of 6mmin 6 months i.e. on passage of 12 to 13 GMT.

- On many occasions reconditioned CMS crossings aregetting chipped off quickly and are not serving for more than3 to 4 months after their insertion.

- Increased frequency of reconditioning of switches and onpassage of every 60 GMT is recommended.

- GR pads get crushed at a faster rate as compared to otherthan heavier axle load routes. The problem is acute beneathcrossing portion of turn outs.

- To sustain the maintainability provision of Rubber Pads madeout of Nylon Conveyer Belt 10mm thick is tried and theresults are encouraging.

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5.5 On loop linesWherever the axle counters are provided the sleeper spacing willnormally more than 60 cm and hence at such locations heavieraxle load will cause more rail seat stresses and crushing of rubberpads etc.

5.6 On Glued jointsAt the glued joint location, the existing system of fittings i.e, GRSP/J clip is causing lesser toe load and hence the more impact forceswill be likely under heavier axle load. For better riding and durabilityof Glued Joints, it is necessary to adopt new glued joints clipsquickly.

5.7 BridgesNo abnormalities were noticed on bridge structures after introductionof CC+8+2 in physical inspection. It has to be watched further forcoming to any conclusion on the effect of CC+8+2 on bridges. Thetrack parameters on girder bridges are getting disturbed at frequentinterval. Alignment on girder bridges and approaches are gettingfrequently disturbed. The experience of Bridge No.292 ( 33 x 12.2 +1 x 9.15 spans ) with channel sleepers has shown that rubber padsand elastromatic pads are getting wornout/crushed resulting in creep.The fittings of channel sleepers also getting loosened frequentlyand need to be tightened more often. Similarily 40% of GR pads (T-5199) of newly laid channel sleepers during 7/2007 on bridge No.427Km.93/1-4 (GNT division) (11x18.29m span) are badly crushed/cutand worked out from its position at free joints as well as at mid railwithin 5 month period, similar is the situation at Bridge No.408 whichwas laid during 11/2006. Prolonged continuation of this situation willlead to dent in rail foot and sleeper seat and ultimately rail fracture.

Remedial Measures suggested:

i) Frequent tightening of fittings will have to be ensured to avoidplay between bottom of Rail and GR pad.

ii) Replacement of fittings with castle nut arrangement or GFNtopi nut which prevents loosening of fittings.

iii) Replacement of normal GR pads below channel sleeper with25mm single piece elastromatic pads with holes drilled atsight to suite the rivet location.

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iv) Use of H. Beam sleepers in place of channel sleepers isrecommended as the H.Beam sleepers are having lessfittings, and also provided with Elastic Rail Clips and all theabove problems can be totally eliminated.

v) Replacement of smaller span upto 9.15 m with PSC.

6.0 Infrastructural Requirements to Sustain the Track Structurefor Running of Higher Axle Loads:With above discussion it is understood that track inputs in the formof men and machinery have to be increased to sustain themaintenance of P.Way for running of heavier axle loads. At presentthe P.Way staff position in Group C and D category up sep-09 inGuntakal division shows that there are total 1394 vacancies availablewhich includes 887 trackmen vacancies. Hence the manpowerproblem is going to become most critical area in time to come. Dueto depletion of gang strength and also growing age of availabletrackmen, the existing pattern of maintenance may not be workablein future. So there is a requirement of realistic assessment andreorganization of existing maintenance units duly adopting moremechanized maintenance pratices. There are various railways in worldwhich are even carrying more loads than CC+8+2, so what are theirpractices?

7.0 International Maintenance Practices :-International Practice for High speed as well as Heavy-haul trafficroutes is fully mechanized system for their track maintenance. Manualis only for the operation and maintenance of machines, co-ordinationof machine working and attention to assets failures. The systemsdeploy a convoy of machines(ballasting, grading, tamping, anddynamic stabilizing) which after a round of maintenance render thetrack fit for full speed with retentivity of up to 4-5 years. Preventive aswell as corrective rail grinding are an essential component ofmaintenance of tracks, to keep the rail profiles for optimum rail wheelinteraction to prolong the life of rails and wheels. No railway systemis adopting various patrolling as is being done by IR.

8.0 IRPWM Provision for Mechanized Maintenance:-Present system of track maintenance: As laid down in Indian RailwaysP.Way Manual, three tiers system of track maintenance is being

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adopted on I.R for sectors nominated for mechanized maintenance.This has been adopted mostly on concrete sleeper track as under

(i) On track machines (OMU)

(ii) Mobile Maintenance Units (MMU)

(iii) Section Gangs (SG)

Tier-1: On track machines unit(OMU) : The work of systematicmechanized maintenance of track will be done with help of heavy ontrack machines which include tie-tamping machines for plain trackand turnouts, shoulder ballast cleaning machines, ballast cleaningmachines, ballast regulating machines and dynamic track stabilizers.These machines shall be deployed to carry out the following jobs:

(a) Systematic intermediate tamping of plain track as well asturnouts;

(b) Shoulder ballast cleaning, ballast profiling/redistribution,track stabilization, periodical deep screening.

(c) Renewal of PQRS & TRT machines

(d) Welding by Mobile Flash Butt Welding machines.

Tier-2: Mobile Maintenance Unit (MMU) : The work of picking up ofslacks and other related works will be done with the help of MMU-I &MMU-II and their functions will be as follows:

(a) MMU-1 (Rail bound vehicles based). One with each PWI in chargewith a jurisdiction of 40-50 Kms double line or 90-10 Kms singleline. 459

(i) Need based spot tamping:(ii) Casual renewal and repairs except planned renewals: In Situ

rail welding.

(iii) Overhauling of Level Xing’s.

(iv) Replacement of glued joints; Rail Cutting/drilling andchamfering

(v) Permanent repairs to fractures

(vi) Creep or gap adjustments involving use of machines;Distressing of LWR/CWR.

(vii) Loading/Unloading of materials & other misc.functionsassigned.

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(b) MMU-II (Road Vehicle Based). One with each sub-division.

(i) Reconditioning of turnouts

(ii) Minor repairs to the equipments of MMU

List of equipments for MMUs:

(i) Mobile Maintenance Unit-I (MMU-1)Spot tamping machines like track tampers and lifting jack,rail cutting and drilling equipment; Rail welding equipments;Distressing equipments such as Rail tensors etc; gas cuttingequipments; material handling equipments; safety & protectionequipments; inspection gadgets & communicationequipments.

(ii) Mobile Maintenance Unit-II (MMU-II)Points and Crossing reconditioning equipments such asWelding Generator; Arc welding equipment; Hand held railgrinder; Equipments for minor repairs such as spanner &gadgets.

Tier-3: Section Gangs: It will perform the following functions:

(i) Patrolling of track viz keyman’s daily patrol, Hot/coldweather patrolling; Monsoon patrolling; Watching vulnerablelocations.

(ii) Attention of emergencies viz temporary repairs of fractures.

(iii) Need-based attention to bridges, turnouts, SEJs andapproaches of level crossings.

9.0 Ground Realities :-There is an annual programme of maintaining the concrete sleepertrack where works have been nominated for pre-monsoon, monsoonand post monsoon period. Though theoretically there is three tiersystem of maintenance, but the ground realities are quire different.Some of the important issues are as given below:

(i) Working of On-Track machine(OMU) Unit: No doubt heavy trackmachines are being used for tamping the track, but their output islimited because of non-availability of regular traffic blocks. Even withthe introduction of corridor blocks, the availability remained only tothe tune of 50%. Many of the pre-tamping & post-tamping works as

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well as works like deep screening of ballast, and ballast profiling etcare also being done manually.

(ii) Works of Mobile Maintenance Units (MMU): Other attention totrack except for tamping like casual renewal and repairs etc is mostlybeing done by manual labour. Few small track machines are availablewith PWIs/AENs, but in the absence of proper repair/maintenancesystem as well as their transport arrangements use is very limited.At some places AMC is in place. There are hardly any Rail-cum-Road vehicles and the transport to site of small machines is quitedifficult.

(iii) The work load & pressure is very heavy on grass-root level oftrack maintenance staff particularly on PWIs (Section Engineer)leaving very little time for effectively maintaining the track.

(iv) Small Track Machines:

a) Poor availability of latest small track machines; some of themachines are old & outdated. All machines run on their ownengines making them heavy and difficult to handle. 461

b) No proper arrangement and expertise for repairs/maintenanceof these small track machines.

c) There are no rail-cum-road vehicles and the transportation ofsmall machines is an upheaval task.

(v) Gang men for maintenance jobs

a) Large number vacancies of gang men (About 15 to 25%).

b) Most of gangmen are illiterate.

c) Gagmen have to carry out strenuous job. The age group ofgangmen is quite high about 50% gagmen in some of thebeats in age group of 45-50 years. This is affecting thequality of work.

(iv) Non functional work done by gangmen like security patrolling etcis very heavy (10 to 15%).

10.0 Suggestions to improve man management for trackmaintenance:-It has been observed that maintenance inputs have gone up on heavyhaul sections. To meet the increasing maintenance needs due to

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running of high axle loads in present time and still higher Axle load inthe near future, this is the time to act in improving the man managementfor track maintenance.

1 Better Training to P.Way Staffa) Faculty member of training institutions (Trainers) to be

competent persons who are interested in this type of job.Proper incentives to be planned for them. Faculty membercan be got trained by foreign leading training institutes.

b) Intensive training for mechanization of track of modern trackto be given to gangmen, P.Way Mistries & PWIs so that theycan maintain track efficiently and economically.

2 Better quality & availability of small track machinesa) Small track machines selected should be of latest type giving

good output and least maintenance.

b) In each DEN/Sr.DEN’s jurisdiction there should be repairworkshop for repair and overhauling of these machines or atleast at divisional level. The track machines sent for repairsshould be repaired immediately & in intervening period, aservice machine should be given which can replace the existingmachine.

3 Rethinking about inspection schedule of track inspectionWith introduction of concrete sleeper & track machines thefocus on items which can be attended such as excessive wearon crossing, loose bolts & fittings etc.The inspections scheduleis also required to be modified to suit the modern track.

4 Better Social environments: The Hqr. Of AENs/PWIs should berevised based on the requirement of education medical attentionto these officials & their families. Suitable changes can bemade without affecting the duties/responsibility of P.Way staff.

5 The gangmen as well as sectional engineers which are safetycategories staff should be given time bound grades, so thatthey have adequate incentives to carry out the work.

6 The cadre & recruitment of gangmen should be so planned thatat least 25% Gangmen will be ITI qualified so that they canhandle the requirement of modern track & track machines.

7 Outsourcing more number of gang activities:- In view of the large

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gang men vacancies and absenteeism, already some activitieslike pre tamping and post tamping operations, cleaning of drains,cess repairs, attention to cuttings & trolley refuges are beingoutsourced. Some more activities like shallow screening, overhauling of Level Crossings, curve greasing, ERC greasing alongwith sealing of liner contact area etc can be outsourced to offload the pressure on gangs.

11.0 Steps to be taken to introduce 100% mechanization :1) Provide computer to all the SSE/P.Ways’ and AENs duly linked

and having facility of broadband connection ( Net working)

2) Set up workshop for repairs and supply of small track machines,

3) Provide Rail cum Road Vehicle with each PWI

4) Provide a road vehicle with each AEN

5) Withdraw all the tools and plants being used for manual

6) Withdraw all present inspection registers and provide newinspection

7) Replace existing tools and plants of key men and provided withonly those tools required for mechanized maintenance like ClipApplicator etc

8) Provide Automatic Track Parameters and Feature RecordingMachine with each PWI

9) Rail Grinding machine: Mixed traffic routes by and large needmore frequent maintenance activities to restore geometricstandards than structural adequacy related maintenance works.In heavy haul operations rail/wheel interaction plays a veryimportant part in the performance of rails and wheels particularlyon curves. Excessive rail wear, rail corrugation, rail surfacedefects, gauge corner fatigue defects are problems generallyfaced. Therefore, for heavy haul systems Rail Grinding as majormaintenance activity combined with Rail lubrication to enhancethe rail life and cost savings associated with it and to preventpremature rail failures affecting train running.

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12.0 ConclusionFrom the experience gained so far in Guntakal & Guntur Division, itcan be concluded that by CC+8+2 loading, early deterioration isnoticed in some track components like CMS xing, rubber pads atsome location, tongue rails, rails on ghat sections.

In order to meet the requirement of Heavier Axle Loads, it is the needof hour to strive for introduction of 100% mechanized trackmaintenance, deployment of rail grinding machine, improving qualityof welding, sustained efforts to eliminate AT welds and automatic raillubricators. This is in addition of efforts to be made for reorganizingexisting track maintenance strategies at field staff level.

For this, there are various aspects which is to be ensured like bettertraining to P.Way staff, better quality and availability of small trackmachine, better social environment for SSE/P.Ways, JE/P.Ways etcand offer career planning of P.Way staff.

* * *

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Overcoming the Challenges of WeakFormation for Heavier Axle Load - Formation

Rehabilitation By Mechanised Blanketing

Munna Kumar*Manohar Reddy**

L. Narender Reddy***

Sr. DEN/Co-ord/HYB/SCRDEN/Lines/HYB/SCRADEN/NZB/SCR

SYNOPSIS : Rehabilitation of bad formation has been a challengeto Railway Engineers for quite some time and so far the search for acredible method which can be implemented without much trafficdisruption and which gives reasonable rate of progress is still on.There are solutions available. But a feasible solution which takesinto account the traffic requirement, the availability of material andease of implementation ensuring reasonable progress simultaneouslyhas not been in sight so far. Hyderabad Division has successfullytried a method for formation rehabilitation in which full width blanketingis done by track dismantling method which takes into account thetraffic requirement as well as reasonable progress of work dulyconsidering the technical requirements for formation rehabilitation.

1.0 Extent of Formation Problem on Indian RailwaysOn Indian Railways 700 km of track is under permanent speedrestriction and approximately 2000 km of track requires impositionof temporary speed restriction because of weak formation. Due toweak formation track components like rails, sleepers and fittings areput to additional stress which results in their premature failure. Forrunning the traffic safely, weak formation requires much more attentionthan the normal track; hence the maintenance resources areunnecessarily put to severe strain. This leads to extra cost ofmaintenance and additional lifecycle cost of replacement. Needless

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to say that temporary and permanent speed restriction put severesqueeze on system throughput which results in loss of potentialrevenue as well as increased operating cost. To sum up weak formationis too costly for the Railways to be ignored and left unattended.

Further running of higher axle load is going to aggravate the existingproblem and may result in surfacing of problems at some of thoselocations where the problem has not been observed so far. Hence astrategy has to be developed to get rid of weak formation not only forpresent operational requirement and axle load but also keeping inview future scenarios.

2.0 Importance of Formation:Track consists of sub-structure and super structure. Formation aswe all know is part of sub-structure and in any structure nocomponent/link can be allowed to be kept weak as it nullifies all thegains which we are supposed to make out of other strongercomponents. Hence, the formation has to be equally strong as rails,sleepers, fittings etc. In fact in permanent way nothing is permanentexcept formation. Rails, sleepers, fittings and ballast get renewedand also get upgraded from time to time, but formation is supposedto serve for the whole life of track and it is not supposed to be replacedin normal course (as a life cycle), until and unless there is a problem.Whenever such problems are identified then also formation is to betreated/rehabilitated but is not to be replaced completely. Hence, itbecomes still more important that formation is strong enough to takecare of all future requirements of loading, traffic density etc. Majorhitch in rehabilitation of formation is to get the work done with minimumtraffic disruption and to achieve desired compaction in the short spanof whatever traffic block is given, duly ensuring that reasonableprogress is achieved.

3.0 Formation Failures – Symptoms and Causes:The failure of formation takes place in different forms and commonsymptoms and causes are listed below:

3.1 Heaving of Base Beyond Toe of Bank.This happens because of sub-base failure. Whenever natural groundon which formation has been laid is too weak to support the loadcoming over it, the soil of the natural ground fails under the load andresults in heaving up of ground beyond toe of the bank.

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3.2 Slope Failure or Excessive Deformation of Banks Slopes -This failure takes place because of poor subgrade or fill materialused while making the formation. This failure may also take placebecause of inadequate slope of the bank.

3.3 Heaving of Cess, Ballast Benetration, Mud Pumping, Crackin the Formation.These are the most common symptoms encountered at the sitehaving formation problem. The reason for all the above causes isthat the top layer of formation is not strong enough to take care ofthe concentrated load coming through ballast.

4.0 Why Top Layer to be Different?The top layer of formation directly supports the ballast. These ballastsare hard angular particles which do not transfer the load uniformly onthe formation. The sharp edges of ballast result in stressconcentration on formation. Further, the angular shape of the ballastresults in the vertical loads getting modified as partly vertical andpartly horizontal load resulting in tensile stress over the top surfaceof the formation. If top layer of formation is not well compacted andstrong enough to take this horizontal component of load, the ballast

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penetrates into the formation resulting in disturbance of the geometryof the track. Other layers of formation except top layer are subjectedto uniform vertical stress all along the surface and hence there is nohorizontal component of load transfer at these layers. This is thereason why the top layer of the formation has to be much morestronger than the bottom layer of the formation. Keeping this in mindRDSO has issued guidelines from time to time regarding the qualityrequirement for the top layer as well as for the other layers of theformation.

5.0 Guidelines For Blanketing On Indian RailwaysThe first guidelines for earth work were issued in August 1978 byRDSO. As per this guideline blanketing has to be done for a thicknessof 30 cms while making the formation for normal soils. In case thesoil is weak the thickness of this balanket layer should be increasedto 60 cms. In 1987 RDSO issued new guidelines. As per this guidelinethe blanketing layer in all cases has to be 1 meter. This was decidedtaking into account future growth of traffic, increase in axle load etc.

These guidelines were further modified in 1991 and it was stated thatthe thickness of blanketing layer will be decided by the Chief Engineerconcerned subject to a minimum of 30 cms. RDSO report in June’93, suggested that blanketing of 1 meter thickness must be providedin all cases of new line and doublings. In 2003 a comprehensiveguideline was issued by RDSO which for the first time stated thatdifferent thickness of blanketing should be done ie., 45 cms, 60 cmsand 100 cms, depending on the quality of subgrade of the soil. Itwas further decided that this blanketing layer is sufficient for 22.5tonnes of axle load.

Puncture of ballast - Loadingpattern on top of formation

Loading pattern at otherthan top layer

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6.0 Blanketing Practices World OverThe blanketing practices world over are listed below:

6.1 UIC – It recommends blanketing thickness of 15 to 75 cmsdepending on subgrade of the soil. It also recommends use ofgeotextiles depending on subgrade soil. The quality of subgradeand blanketing layer is determined by its CBR value instead of thesieve analyses.

6.2 Japanese Railways – It recommends 5 cms of bituminousconcrete as the top layer of the formation below which 25 to 75 cmsmechanically stabilized crushed stone are provided. Below this layeratleast 3 metres of good soil is provided depending on the height ofthe bank.

6.3 American Railways – They recommend 30 cms of sub ballastover good quality of soil which is used in formation. The plasticity ofthe soil used in formation must be more than 12.

6.4 Australian Railways – They recommend 15 cms of blanketingover 50 cms of subgrade of CBR above 8 or 100 cms of sub grade ofCBR between 3 and 8.

7.0 Evaluation of Various Methods of Formation Rehabilitationon Indian Railways – RDSO report No.GE 39 of 2003RDSO has published a report duly evaluating various methods adoptedfor formation rehabilitation on Indian Railways and a study has beenpublished in the form of the above report. The efficacy of variousmethods as brought out in the report is reproduced below:

7.1 Lime Slurry Pressure Induction (LSPI) – This method wasused for bearing capacity failure and for the formation where excessiveswelling/shrinkage was reported. LSPI aimed to change the chemicalcomposition of the soil so that swelling and shrinkage of the soil iskept within limit. It was found that it does not change the soilcomposition. Further lime is leached out due to rain. This method isnot being recommended. This method was used in patches inPanskura-Haldia section of SER.

7.2 Ballast Piling – In this method vertical hole is drilled and ballastis filled up which acts as support as well as drain for the water toseep out. It was found that in the hole, lot of water gets collectedwhich had no passage resulting in further weakening of formation.

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7.3 Cement Grouting – This method is similar to LSPI. It wasfound that only localized lumps were formed without any resultantchange in soil characteristics. This method was used in Bapatla-Sundur section of SCRly in 1977. No permanent improvement information has been observed at this location.

7.4 Cross Drain – In this method coarse material are filled byproviding cross drains. However, these coarse material get washedaway. This causes more damage to the bank than being useful.This method was used in Barahia – Mankatha section of East CentralRailway in 1992.

7.5 Polyethene or Similar Impervious Sheet – The sheet isprovided in the formation to arrest the water from further entering intothe formation. However, it leads to increase in moisture contentbelow the sheet which results in reduction of soil strength. Thismethod was used in Rajkharsawan – Sini section of SER.

7.6 Geo Textiles – Geo textiles have been used below ballast atmany places. However, this alone does not help. It has to be usedalongwith blanketing. It was done in Sandila-Lucknow section ofNR.

7.7 Partial Blanketing – In this method blanketing material is usedto increase the cess width as well as the slopes which results inincrease of counter weight on the formation from sides. This methodworks only when the ballast penetration has stopped.

7.8 Widening of Bank – This also has the effect of increasing thecounter weight on slope of the bank which results in extra confinementof load bearing strata of the formation. This also works only whenballast penetration has stopped.

7.9 Full Width Blanketing – This method involves replacement/addition of blanket material on the top layer of the formation. This isthe only method universally accepted by world Railways world over.Unstable formations have already been eliminated by this method.Some of the Railways use this method in combination with geotextiles.

Apart from this, S C railway has tried the formation rehabilitation bysand treatment method in which sand is fed into the track in stagesand track is vibrated with DGS. This leads to penetration of sand intothe formation filling the cracks resulting in stabilization of formation.

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The short term results are satisfactory and very encouraging; Howeverlong term improvements needs to be still evaluated.

8.0 Experience Over Indian Railways With Blanketing – RDSOReport No.GESR.0017/2008

RDSO has published the above report which lists out ballastpenetration into the formation in the section where blanketing hasbeen done and those sections where blanketing has not been done.The details of ballast penetration are given below:

Ballast penetration details without blanket

S.No Section GMT Penetration (cm)

01 Colonelganj-Jarwal Road 73 0 to 100

02 Allahabad - Kanpur 300 0 to 26

03 Bareilly – Moradabad 180 2 to 35

04 Bareilly – Moradabad 230 5 to 70

05 Bareilly – Moradabad 216 1 to 15

06 Bareilly – Moradabad 230 0 to 20

07 Bareilly - Moradabad 230 2 to 26

08 Ujjain-Bhopal 64 38 to 50

09 Moradabad- Ghaziabad 25 2 to 17

10 Secunderabad-wadi 130 0 to 12

11 Secunderabad-wadi 130 5 to 13

12 Itarsi-Dularia 71 79 to 125

Ballast penetration detail with blanket.

S.No Section Thickness GMT Penetration

(cm) (cm)

01 Jarwal Road - Burthwal 60 24 Nil

02 Bilaspur-Dagori 100 81 Nil

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03 Cuttack - Paradeep 100 156 Nil

04 Cuttak - Paradeep 100 35 Nil

05 Korba-Gevra Road 80 to 100 61 Nil

06 Sarona - Bhilai 80 to 100 113 Nil

07 Gurap - Sakthigarh 55 to 65 10 Nil

08 Dharamvaram - Penikonda 95 to 105 19 Nil

09 Shoranoor - Mangalore 90 to 95 31 3 to 22

10 Rajathgarh - Talchar 24 to 30 393 1 to 6

The report also discusses about the sections where blanketing hasnot resulted in much reduction of ballast penetration. Mostly thereasons were poor quality of blanketing material being used in thesesections.

9.0 Various Methods Tried in the Past for Full Blanketing ofFormation Under Traffic

9.1 Alluminium Alloy Girder Method -In this method a light weightgirder is used as a relieving girder below which formation is dug andblanketing material is filled up. The compaction is done with portablecompactors of low capacity. The blanketing by this method wasdone in Wadi – Nalwar section of SCR. It was also done in Sholapurand Delhi division. In SCR there were initial problems because ofinadequate compaction. However, track got consolidated under trafficand the problem due to bad formation was eliminated. The onlyproblem with this method is that it is very slow (progress 15 mts/day) and desired compaction of blanketing material is difficult toachieve immediately.

9.2 Manually Operated Portals - This method was developed bySER. In this method manually operated portal crane similar to PQRScranes are used with auxiliary track to dismantle existing track andblanketing is done. After blanketing track is put back with the help ofthe same crane. Because of auxiliary track the problem of compactionremains there in this method also.

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9.3 CC Crib/Rail Cluster Method - In this method rail clustersupported on CC crib is used to support the track. Below the railcluster formation is dug up and blanketing material is filled up. Asthe work progresses rail cluster and CC cribs are shifted forward. Inthis method blanketing of 50 cms thickness is possible. Therequirement of block is only for shifting of rail cluster and crib whichis about 45 minutes. This work was done in Kamptee yard nearNGP of SER. The compaction in this method is also achieved underpassage of traffic hence caution order of very long duration is requiredto be imposed.

9.4 Lifting of Track with Deep Screening - In this method trackis lifted on banketing material by first removing the ballast andcompaction is allowed under traffic. Track is further lifted on ballast.In this method also long duration of caution order is required forcompaction. However, little or no traffic block is required for carryingout the work. This method is labour intensive. This method wasused in Sirpur town-Vempally, Manikgarh-Garchandoor sections ofSCR, Chennai-Arakonam section of SR and Cuttak – Paradeepsection of East Coast Railway.

9.5 Blanketing by Track Dismantling – Although blanketing bytrack dismantling method has been tried earlier, but it was found thatthere is lot of scope for improvement in working by mechanising thedismantling of track as well as removing of ballast, spreading ofblanketing material and rolling.

10.0 Method Developed by Hyderabad Division - MechanisedBlanketing by Track Dismantling

The method has been evolved over time and at present HyderabadDivision has developed a scheme by which entire blanketing operationincluding track work is mostly mechanized resulting in good progressof work.

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Conversion into free rail Removing of Rail Panel from Track

Removing of Ballast Spreading of Blanketing material

Rolling by Vibratory Roller Ballast Spreding

10.1 Description of the Method : First the existing rails (LWR converted to 10 Rail Panel) are removedand replaced with single rail panel of service rails. Ballast is alsoremoved to some extent before the block. Blanketing material isstacked on the cess from the toe of the bank where it had beenstacked earlier. During block single rail panels are removed fromtrack by crawler mounted heavy duty cranes which are operatedalong the bank. 2 nos. of such cranes were utilized for the reason ofexpediting the progress as well as to take care of any eventuality of

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breakdown of one of the cranes. This is followed by removal of ballastwhich is done with the help of excavators. The track ballast is removedand kept on either side of cess. The naked top of the formation isrolled lightly and the blanket material is spread over it with the help ofexcavators. These spread material is compacted using heavy dutyvibratory rollers giving approximately 15 pass for each layer. Theballast is spread over this compacted layer with the help of excavatingmachines. This ballast layer is also rolled and dismantled trackpanels are put back with the help of crawler mounted crane andtrack linking is completed. Further lifting of track on ballast is donemanually and after doing TRR and track consolidation, caution ordersare relaxed. The work is being done duly taking block of 4 hours inwhich a progress of 200 meters is achieved. So far 20 kms of lengthhas been completed by this method in SC-MUE section of Hyderabaddivision. The blanket layer thickness of 30 cms has been provided inthis stretch. Further, Division is making efforts to increase thisthickness of banket layer to about 60 cms by duly cutting into theformation if required.

Rolling of Ballast Keeping back Track Panels

Connecting the Track Passing the Train

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10.2 Resources Deployed in this Method:

1. 2 crawler mounted cranes of 40 ton capacity

2. 3 Ex-200 excavator machines.

3. 1 Vibro Max roller

4. 80 labourers for doing TRR, lifting of track and working withmachines

5. 1 Water tanker for spreading water during rolling

6. Blanket material required is about 4000 cum/km

7. Ballast required is about 500 cum /km

8. The total cost per km is about 25 lakhs

10.3Advantages of this Method:1. Any blanketing thickness is possible by cutting the formation to

the desired depth.

2. Compaction is done with heavy duty vibratory rollers. Hence longduration caution order is avoided.

3. The speed of work is reasonably good and it can be increasedfurther by deploying multiple set of machines in the same block.

4. The method is suitable for providing geo grid as well as for differentkinds of blanketing material.

11.0 Comparative Study of Track Parameter before and afterBlanketing

• Block Section – BLSA – KEK• KM - 407 to 408• Month - Mar’09

11.1 Tamping Done before Rehabilitation

Year 2007 – 21.01.07 & 06.08.07

Year 2008 – Caution order imposed between April 2008 to July 2008for want of Tamping.

- Tamped on 29.07.08

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11.2 Manual Attention:

• Year 2007 – 22.01.07, 19.03.07, 11.04.07, 05.05.07, 05.06.07• Year 2008- 14.01.08, 06.05.08, 17.06.08, 10.09.08, 17.10.08.

Comparison of TGI values (Km 407 to 408)

Date of TRC run TGI Value Remarks

25.08.2007 52

15.05.2008 39

25.02.2009 65

After Rehabilitation - TRC run not done afterRehabilitation work

OMS Peak Details (Km 407 – 408)

Month KM. 0.20 to 0.25 to 0.30g TO TOTAL No.0.24 g 0.29 g ABOVE

of Peaks

V L V L V L V

Apr’08 NIL (caution order of 50 kmph)

May’08 NIL (caution order of 50 kmph)

June’08 407 4 0 2 0 0 0 6 0

July’08 NIL (caution order of 50 kmph)

Aug’08 NIL (CSM tamped)

Sep’08 407 1 0 0 0 0 0 1 0

Oct’08 Nil

Nov’08 Nil

Dec’08 Nil

Jan-09 408 1 0 0 0 0 0 1 0

Feb-09 408 1 0 0 0 0 0 1 0

Apr. to Aug’09 Nil

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12.0 Drawbacks of the work done so far:1. The blanketing thickness being done so far is 30 cms only. Therecan be a doubt about the effectiveness of thickness of blanketinglayer of 30 cms. However, as discussed earlier the blanketingthickness can be increased by duly cutting the formation to suitabledepth. Further as per the revised guidelines of RDSO even 30 cmsof blanketing will be suitable enough for present day loading.

2. There can be a problem in electrified sections in operating cranesfor removal of panels etc. However, by selecting suitable crane or byusing Ameca T-28 crane the problem can be solved. Further in REarea cutting into formation will be a must as the level of track cannotbe raised for blanketing.

13.0 RDSO Guidelines of 2008 for Blanketing:RDSO has issued guidelines for blanketing of formation duly takingthe requirement of different axle loads and also taking into accountthe subgrade material of the formation. Further, it has issued guidelinesfor soil classification based on CBR value instead of particle sizedistribution. These new guidelines are in line with UIC guidelines forblanketing and are much more scientific. The guidelines also saythat the blanketing thickness prescribed earlier were on very highside, blanket thickness recommended now is as low as 150 mmwhich will be very easy to be provided in the field in running trafficcondition. The salient features of the guidelines are as under:

BLANKET LAYER

PREPAREDSUB-GRADE

SUB-GRADE

OPTIONALGEOTEXTILE

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Type of Formation Layer Minimum Required CBRValue

Blanket / Sub-ballast Layer 50 %

Prapared Sub-grade/ Top Layer 8 %of Formation

Sub-grade/Embankment Fill 5 %

Explanatory Notes : 1. Categories of soil Quality :

Sl. Soil Description w.r.t. Fine- IS ClassifiacationQuality Particles (size less than to Referred Soil

75 micron) Quality (Suggestive)

1. SQ 1 Soils containing fines CL, ML, CL,ML,CI,MI> 50 %

2. SQ2 ** Soils containing fines from GM, GC, SM, SC12 % to 50 %

3. SQ3*** Soils containing fines GW, GP, SW, GW-< 12 % GM, GW-GC, SW-

SM, GP-Gm, GP-GC,SP-SM, Sp-SC, etc.

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Proposed Two Layers System Of Blanketing On Track Formation ForAdoption On Indian Railways

(Reference Calculations based on UIC practices in terms ofUIC Code 719R-1994)

SL Soil Quality Top Layer of Recommended RemarksCategory in Formation Thickness lareal ofSub grade (prepared Blanket for lute leadsneed in Subgrade)embankment

Quality Thick- 20 T 22.9T 25 T 30T 32.5 T(CC+ (For8+2) D.F.C.)

1 SQI SQ1 - 300 350 400 600 750 Geo-synthetiks to be used

2 SQ1 SQ2 500 150 200 250 450 600 Geo-synthetiks to be used

3 SQ1 S03 5OO 150 150 200 350 500 Goo-synthetics is optional

4 SQ2 SQ2 - 150 200 250 450 600 Geo-synthetiks to be used

5 SQ2 SQ3 350 150 150 200 350 500 Geo-synthetics is optional

6 SQ3 SQ3 - 150 150 200 350 500 Goo-synthetics is optional

Particle Size Distribution :Material shall be well graded with typical particle size distributionas follows :

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IS Sieve Percentage Passing Nominal Size (20mm)

53 mm 100

37.5 mm 100

26.5 mm 100

19.0 mm 95-100

9.5 mm -

4.75 mm -

2.36 mm 30-80

0.075 mm 6-10

Atterberg Limits :

• Liquid Limit : Maximum 30 (35 for and areas)

• Plastic Limit : Maximum 20

• Plasticity Index : 2 -10 (2 -IS for and areas)

• Linear Shrinkage : Maximum 3%

Maximum Dry Density : Minimum 2.0 t/cum

Soaked CBR : Minimum 50%, determined on material compactedto 95% (min.) of Maximum Dry Density

General Soil Type USC Soil Type CBR Range

GW 40 - 80

GP 30 - 60

GM 20 - 60

GC 20 - 40

Coarse-grained soils SW 20 - 40

SP 10 - 40

SM 10 - 40

SC 5 - 20

ML 15 or Less

CL LL < 50 % 15 or Less

OL 5 or Less

Fine grained soils MH 10 or Less

CH LL > 50 % 15 or Less

OH 5 or Less

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14.0 Conclusion:

• The problem of formation failure is going to gain much importancein view of increased axle load, demand for increasing line capacityby reducing PSR and TSR, and need to bring economy inoperation as well as to bring down asset life cycle cost.

• Formation even made of soil with sufficient bearing capacity mayfail in punching and will need blanket cover.

• Blanketing is the only reliable method for formation rehabilitationhaving symptoms of ballast penetration.

• Depending on the traffic pattern selection of blanketing methodcan be done.

• It is possible to lay any thickness of blanketing layer.

• With reduced blanket thickness requirement and with use ofgeo grid reasonable progress can be achieved even in busyroutes.

• Use of Ameca crane can be tried in RE area.

• Multiple working units is going to increase the progress in thesame block.

• Apart from strengthening the top layer, widening of bank/provisionof sub-bank will address the problem of sub grade weakness.

15.0 Recommendations:1. The present specification for blanketing material is stricter thanthe previous specification. As per present specification blanketingmaterial should have CBR of 50 and above with MDD of 2.0 ton percum. It is very difficult to get a naturally occurring material of thisspecification. In fact only well graded gravel will meet the abovespecification. The guidelines issued by RDSO do not specify themethod by which a blanketing material of above specification can beobtained. It will be useful to the field staff if RDSO comes with theblending proportions of different materials like quarry dust and gravelof different sizes up to 20 mm which are to be mixed to achieve theabove specification.

2. In field blanketing of new formation during construction of newlines or doubling is much easier than blanketing of formation of running

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track. The RDSO guidelines has not specified if any relaxation canbe given wherever rehabilitation of formation is to be done for runningtrack due to difficult circumstances at the field level in carrying outthe work. These relaxations can be in the form of thickness ofblanketing material etc. It is recommended that based on the studies,the minimum thickness of blanketing for rehabilitation of track maybe advised separately.

3. It will be also useful if guidelines are issued as done for bridgesregarding rehabilitation of formation whereby the horizon axle load isprescribed based on the future traffic for different routes for rehabilitationof formation.

4. The rehabilitation/renewal of formation should be treated as trackrenewal and wherever rehabilitation is to be done it should beconsidered as overdue track renewal arrear. These track renewalarrear should be wiped out in a time bound programme as it wasdone for TRR, TSR etc. duly making rout wise plan and fixing targets.

5. For running heavier axle load a strategy for preventive rehabilitationshould be made even for those stretches where there is no PSR/TSR at present, based on present track parameters, frequency oftrack attention, ballast penetration, type of sub grade soil etc in aparticular stretch. Based on these parameters works of formationrehabilitation should be taken up for catering to future axle load.

* * *

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Impact & Experience of Heavier Axle Load onIndian Railways

M. R.Srinivasan *

*SE/PW/USFD/MDU/SR

1.0 IntroductionTo meet out the demand, of increasing traffic the railway has toimprove their operation efficiency and performance with newtechnology.Operation efficiency means improving performance withthe available resources. The operation efficiency may be improvedby increasing the carrying capacity of coaches / wagons and reducingthe idle time of the coach / wagons with optimum utilisation of linecapacity of the track.

The figures shows the freight load carried by IR’s

Year Freight Load Carried inMillion Tonne

2004-05 626

2005-06 682

2006-07 725

2007 -08 778

2008-09 833

2009-10( Proposed) 882 ( proposed)

The freight load proposed to carry during 2009-10 is 40% higher thanthat of during 2004-05. How we could achieve this target, theoreticallyspeaking it is possible only by adding 40 % additional line & wagons.

Synopsis : Indian railways run about 11000 trains every day, carrying5725 million passengers & 833 million tonnes of goods traffic in ayear. Every year the traffic carried out is increasing due to industrialgrowth and increase in population.

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But due to the constraint in resources railways have to meet out thetarget by improving their technology instead of simply multiplying itswagons.

Figure shows the operation performance of IR’s with other Railways

Wagon NTKms NTKms NetRailways Km per per wagon per tonne tonnage

wagon per per day per carriedday wagon per wagon

Japanese Railway 258.4 3481 36713 13.47

Indian Railways 211 2723 42237 12.9

French National Railways 73.4 1600 11681 21.79

German Federal Railways 70.6 1115 9139 15.79

Italian State Railways 53.4 962 8006 18.01

The carrying capacity of IR’s is less, eventhough its wagon utilisationis high when compared to other railways. To improve this, we have toincrease the carrying capacity of wagons i.e. by increasing the axleload of the wagons.

2.0 Axle Load & Loading Standard of IR :Axle load is the maximum weight of a train per pair of wheels allowablefor a given section of track. The maximum axle load is related to thestrength of the track, which is determined by weight of rails, densityof sleepers and fixtures, train speed , amount of ballast and strengthof bridges.

IR’s Bridge Loading Standard

Bridge Loading Standard Wagon Load

Bridge Loading Axle load Wagon carrying Axle load

standard capacity

BGML 22.9 t BOXN CC+6+2 22.32 t

RBG 22.5 t BOXN CC+8+2 22.82 t

MBG 25 t BOXN CC+10+2 23.32 t

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3.0 Impact Due to Heavy Axle Load :Due to heavy Axle load, the track stresses and design of varioustrack components will be affected such as ,

1. Increase in track stress

2. Design of rail section

3. Design of sleeper

4. Change in LWR cold and hot temp

5. Gradient & hauling capacity of loco

6. Design of bridges.

7. Improvements in fastenings

8. Man power req due to fast deteriation of track

9. Increase in fatique failure of track

10.Formation problems

4.0 Increase in Track Stresses:Calculation of Track stress, consists of working out of MaximumBending moment at any point in the track. The Bending moment canbe calculated by considering the track as inverted continuous beamand support reaction as wheel loads at a span of wheel distances,considering the sleeper support as multiple point loads acting at adistance equal to sleeper spacing. Then the section of Rail req canbe computed using M=f * z

But the above calculation getting complicated since rail is subjectedto dynamic loads and due to uncertanities in various parameters likesubsoil modulus, climate condition, curvature effect etc , the wheelload is amplified with various factor called dynamic factor, Speedfactor, lateral thrust, irregularities of track, inertia load etc. The netload obtained after such modifications is called virtual wheel loads.but this virtual wheel load is reduced again what is termed as relief ofstresses. Based on the American professor A.N.Talbot the relief stressis due to continuity of the track below the wheels. The elasticdeformation of the adjoining spans is to a certain extent counterbalanced due to continuity of the span. Therefore let’s assume thatthe multipling factor of wheel load and reduction of wheel load due tocontinuity of track may balance each other and take the wheel loadas it is for calculation purpose.

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The BM can be computed using the formula ( Prof A.N.Talbot)

M max = 0.319 W x

x = 42.33 4 √I/μWhere M= Max BM in tonne -cm

x = Distance from the load to the point of contraflexture in cm

I= Moment of Inertia in cm4

W=lsolated wheel load in tonnes

μ = Subgrade modulus in kg/cm2

Based on the formula the 8M and Longitudinal stress found for variouscombination is tabulated below.

μ for f(Long TempWheel various Section stresses stress for Total

Load load in type of I Moment modulus due to 30 deg stresstype tonnes soil bending) N/mm2 N/mm2

N/mm2

30 (Soft 3055 335.50 (MBG 12.5 clay) (for 536.19 for 60 159.81 90 249.8

60 kg) kQ)

500 (for 3055 335.50 (MBG 12.5 dense (for 265.37 for 60 79.09 90 169.1

sand) 60 kg) kg)

450000 335.50 (MBG 12.5 ( for 3055 48.43 for 60 14.432 90 104.4

rock) (for kg)60 kg)

permissible longitudinal stress= 220 to 250 N/mm2

For the worst combination of loading and formation, the total stressis less than the permissible long stress. If axle load increased morethan MBG standard then we have to go for higher UTS rails.

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5.0 Design of Rail SectionBased on the experiment, the Axle load carrying capacity of rails is512.06 times of weight of the rail section. The existing 60 kg railsection having the carrying capacity of 60.34*512.06 = 30.89 t whichis more than the MBG load. 60 kg rail is having the capacity to carryaxle load upto 30 tonne.

6.0 Design of Sleeper6.1 Factor Influencing The Design of Sleeper:1. Static and dynamic loads imposed on the rail seats depends uponthe type of track ( straight or curved) , its construction and standardof maintenance, the axle load and axle spacing, the runningcharacteristics, speed and standard of maintenance of vehicle.

2. The ballast reaction of the sleeper is based on the shape of sleeper,its flexibility and spacing, the unit weight of the rail, the standard ofmaintenance of track and characteristics of ballast.

The static wheel load of 11 tonne ( Axle load 22 tonne) at the railhead was found to cause a vertical sleeper reaction of 6 tonne onstraight track. To allow for dynamic effect, the design load adopted is15 tonne at each rail seat based on static load 6 t which is multipliedby a dynamic factor of 150% under different condition of loading andspacing of sleeper.

The figure shows the BMD & loading pattern PSC sleeper of T2495under different condition

The T2495 sleeper having the capacity to carry BM at rail seat of12.77 KNm and 13.37 KNm at the centre of sleeper. Study fromGerman Railways says that the percentage of failure due to crackingof sleeper is in the order of 1 % when sleeper having BM capacity ofmore than 10 KNm at centre, . Hence IR design of T2495 having BMcapacity more than 10 KNm at centre to safeguard against the adverseeffect of formation due to black cotton soil .

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Even by increasing the axle load, the capacity of the sleeper can beimproved by reducing the spacing of the sleeper.

Rail section Kg/m Axle load tonne Sleeper density

57 28 M+6

50 25 M+5

45 22.5 M+4

7.0 Change in the Criteria of LWR Cold and Hot WeatherPatrollingThe additional tensile stress in the track when temperature reducesto 30 degree is 90 N/mm2 . The limit of td-30 has been fixed byconsidering the total stress due to temp as well as stress due toload. If Axle load increases, the track stresses due to load will increaseand it will ultimately lead to revising the permissible value of td-30

As far as Hot weather is concerned the increase in axle load maynot affect the limit of td+20 . But some extra precaution to be takenon curve. Normally for goods trains, this will be subjected to onlycant excess in the curve due to lower speed. Hence the extra axleload may not affect the Hot weather patrolling criteria when comparedto cold weather patrolling.

The destressing temperature ( stress free temp) also affected. Inforeign railways majority of track are track circuited and there thedestressing temp are kept in higher side since rail failure can beeasily detectable due to track circuiting, but buckling may happenwith out any prewarning . Hence it is always safe to keep stress freetemp in higher side of the limit in the track circuited track.

8.0 Gradient & Hauling Capacity of LocoDue to increase in axle load, the loaded weight of the train formationwill increase and the loco should have sufficient hauling capacityunder the worst combination of gradient and climate condition. Theworst combination is when the loco met with the gradient of 1 in 100and greasy/oily rail condition.

The figure shows the hauling capacity and load of the formation underdifferent combination of the loads,

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Calculation of Formation loadinQ (in tonnes)

LoadedWagon Nos of Tare C C C C+ Gross weight

wagons weight with oneBV

BOXN 59 22.5 58.81 64.81 87.31 5165C C+6

BOXN 59 22.5 58.81 66.81 89.31 5283C C+8

BOXN 59 22.5 58.81 68.81 91.31 5401CC+10

8.1 Loco Starting Hauling Capacity ( in tonnes)

Loco Gradient Dry rail Wet rail Oily /class condition condition Greasy rail

conditionLevel 6000 4694 36001/500 5775 4518 3465

WAG5 1/200 3810 3125 22861/150 3198 2660 19191/100 2407 2041 1444Level 10815 7317 64891/500 7169 4850 4301

WAG7 1/200 4738 3360 28431/150 3997 2860 23981/100 3002 2200 1801Level 11550 7814 69301/500 7656 5180 4594

WAG9 1/200 5060 3588 30361/150 4250 3041 25501/100 3205 2349 1923

Hence special precaution to be taken while stopping the formation atthe section having heavy gradient specially in rainy season and suitable

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additional banker loco or multiple loco may be used to improve thehauling capacity.

Before increasing the axle load the section having maximum gradientmay be checked with hauling capacity, if possible regrading of trackmay be proposed to improve the hauling capacity and to avoid thedamage of rails due to wheel slipping.

9.0 Design of BridgesBefore introducing the heavier axle load the loading standard of theBridge designed is to be checked and in addition to that if the olderbridge is designed with lesser axle load than the proposed one, thestrength of the bridge may be improved by using suitable methodsbased on the type of the bridge.

10.0Improvement in FasteningsThe existing mark III ERC is having the Toe load carrying capacity of850-1150 Kg . The mark IV ERC which is under development havingthe Toe load capacity of 1100-1300 kg . GRP should be designed togive more resilience due to heavier axle load.

11.0 Man Power Req. Due to Fast Deterioration of Track :Gang strength formula N=0.95 M K L U (1 +A+B+C)

N=No of men req IKm

K= Correction factor due to modernisation of track

M=Manpower factor

L= Length of track

U=Traffic density factor

A= Formation factor

B=Alignment factor

C= Rainfall factor

U= Traffic density factor based on

GMT 20-25 25-35 35-45 45-55

U 1.4 1.5 1.6 1.7

Increase U by 0.1 when BOXN Wagon PLY >5 per dayIncrease U by 0.1 when speed >110 kmphHence increase in axle load will req additional manpower of 10%

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12.0Increase in Fatigue Failure of Track :If the load is applied gradually, the specimen fails at the ultimateload. In the case of specimen is loaded and unloaded large numberof times, then the specimen fails at smaller load. The phenomena ofdecrease of resistance due to repeated stress is known as fatigue .

The growth of defect will be faster when it is subjected to heavier axleload. Hence suitable precaution to be taken to detect the defectbefore its reaching premature stage. Rail joint should be avoided,since the hammering effect is more in free joint.

13.0Formation Problem :The moment carrying capacity of the rails and sleeper is based onthe dynamic modulus of the formation. The fig shows the dynamicmodulus of various type of soil

Type of the soil Dynamic modulus(KN/m2)

Very soft clay 350-2800

Medium clay 4200-8400

Loose sand 10000-24500

Dense sand 100000-200000

Rock granite 25 to 45*106

Hence if the formation consist of weak soil suitable blanketing to begiven to improve the bearing capacity of the soil.

14.0Conclusion:By considering the various effect due to increase of axle load. Theincrease of axle load play a vital role in goods traffic only, sincepassenger traffic are fully based on speed. Hence instead of increasingthe axle load in the existing track and running mixed traffic it isbetter to have a separate track for goods and passanger traffic. Thepassanger line may be designed as high speed track with low axleload and goods line may be designed for heavy axle load. This willimprove the safety standard of the track as well as reduce themaintenace cost due to lesser cant excess, cant deficiency & lesscorrosion in the goods line.

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References:

1. Foundation Engineering - Dr K.J.Kasmalkar

2. Railway Engineering - Rangwala

3. Prestressed concrete - N. Krishna Raju

4. WTT of Palakkad division.

5. Technical diary - Inst of PW Engineers

6. Objective Railway Engineering - M.M.Agarwal

7. Analysis of structures - S.Ramamirthum

8. IRPWM

* * *

2. 1

Experience of World Railway Systems forRunning of Heavier Axle Loads with Special

Reference to Indian Railways

M.M. Agarwal*K.K. Miglani**

* Former Chief Engineer/Northern Railway** Deputy Chief Engineer/TP/Northern Railway

Synopsis : The phrase ‘Heavy Haul operation’ came into prominencewith the first Heavy Haul Conference held in Perth in Western Australiain 1978. Starting from that beginning, a large number Heavy HaulTrains are being operated now in various countries in the world, inAmerica, Australia, Africa, Europe, Brazil, Scandinavia and UK forlast 3 to 4 decades. Fortescue Railway in Western Australia ispossibly the world’s latest, newest and outstanding heavy haul linewhich has been opened on April 6, 2008. This line already got inprominence during 9th Heavy Haul Conference held in 2009 inShanghai.

The authors have critically examined the problems faced by some ofthe important heavy haul systems in the world railways in constructionas well as in operation, with special reference to Indian Railways.The main problems which require to be specially addressed foroperation of the Heavy Haul trains have been highlighted in the paperalong with remedial measures. It is felt that experience gained fromthese railways can be of utmost use for introduction of heavy axletrains on Indian Railways.

1.0 IntroductionThe phrase “Heavy Haul” (HH) operation probably came intoprominence with the first Heavy Haul Conference, held in Perth,Western Australia in 1978. Heavy Haul (HH) trains operate in someof the world’s most difficult conditions of terrain and climate, with railtemperatures up to 75 degrees C in North West Australia, down tominus 50 degrees C in Canada, and with annual ranges of up to 80degrees C. Trains can be of 250 vehicles giving a trailing weight ofsome 30,000 tonnes and train lengths of more than 3 kms., withtrack curvature of 220m and grades of 2%.

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As back as in 1975-1980 , Heavy Haul trains were being operated inAfrica, Australia, Brazil, North America, Europe and Scandinaviancountries. Growth has been phenomenal in Heavy Haul Operationssince then and in most of the developed nations, these Heavy HaulTrains are running as part of economical necessity.

It is proposed to take case studies of few typical railways and discussthe various troubles faced by them as well as remedial measures inconstruction as well as operation/maintenance of these railways.

It may be brought out that some studies of Heavy Haul trains relateto earlier years. Though there has been lot of technical developmentssince then, yet some of the problems brought out in earlier days arestill relevant in present day context.

The case studies discussed in the paper for running of Heavy Haultrains in different countries of the world not only relate to constructionand maintenance of the track but also of some specific issuesconcerning the track. The case studies discussed in the paper are:

(i) Burlington Railways of North America for maintenance ofHeavy Haul Railway lines.

(ii) Harmersley Railways of North West Australia for maintenanceof Heavy Haul Railway lines.

(iii) Fortescue Railways of Western Australia for construction ofHeavy Haul Railway Line.

(iv) Economics of running Heavy axle load & longer trains inSweden (Europe)

(v) Maintenance of Heavy Haul Corridor of Union Pacific Railway.

(vi) American Railways: Track Transition solutions for Heavy axleload service

(vii) American Railways: Effect of Heavy axle load on BondedInsulation Joints.

It is felt that experience gained by different Railway systems of theworld may be of immense help to Indian Railways specially for runningof 25 tonnes axle load on nominated sections of Indian Railway aswell as for Dedicated Freight Corridor.

Details of the various case studies are discussed in subsequentparas along with conclusion.

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2.0 Burlington Railways of North America

2.1 IntroductionBurlington Railways of North America is one of the oldest HeavyHaul operated railway, constructed in the decade 1970-1980. Trafficcarried in the railway was mostly coal and mixed traffic with an axleload of 30 Tonnes and maximum speed of 75 km per hour. The annualtonnage was 50 HGT. The gauge adopted was standard gauge of1435mm.

2.2 Track StructureThe track consisted of 68 Kg per metre rail & with mostly woodensleepers with cut spikes and also mono block concrete sleeperswith special clips; maximum curvature was 220 metres radius.

2.3 Problems Faced for Running of Heavy Axle Loads:A study carried out indicated the following problems with the trackon account of Heavy Axle loads :

(i) Rails: Rapid rail wear, Rail end batter and dipped joints, CrackedRails, Corrugation of rails.

(ii) Sleepers:(a) Wooden Sleepers - By far the most common wooden

sleeper fastener used was cut spike and rail anchor. Theproblem faced was sleeper degradation causing deformationof track geometry, lesser sleeper life.

(b) Concrete Sleeper – The concrete sleeper fastenersembody is housing forming an integral part of the sleeper,and a self-tensioning spring clip located in the housing Incase of concrete sleeper there was no problem of any typeexcept fastenings.

(iii) Fastenings – Different problems existed on different type offastenings

a) Wooden Sleeper : Problems experienced were lifting andlateral movement of the spikes giving poor gauge.

b) Concrete Sleeper : The problem faced were of lowclamping force (toe load) and low rail creep resistancevalues. Also the rubber pads suffered from abrasion, cuttingand permanent set.

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2.4 ConclusionIt may be brought out that subsequent, up gradation of track structureand deployment of new technology has sorted out many of theseinitial problems caused during Heavy Haul operation.

3.0 Hamersley Railway of North Western Australia

3.1 IntroductionHamersley Railway of North Western Australia used to transport ironore over a standard (1435 mm) gauge single track of 388 kms joiningmines at Tom Price and Paraburdoo with two ship loading points.

Trains consisted of three 2700kw diesel electric locomotives and upto 210 cars with a 30t axle load. Train length was over 2kms, andgross weight about 26,000 tonnes. On the 100km adverse grade of0.4% existed between Paraburdoo and Tom Price.

3.2 Problem faced(i) Embankments: These were constructed quickly in a short span

of about one year without proper consolidation and as suchgave problems of settlement, slippage and even failure.

(ii) Track: Degradation resulting in poor track geometry, fasteningbecame loose, wide gauge and effecting cross levels and othertrack parameters.

(iii) General� The constantly heavy axle loads, rising tonnage and train

frequency had two important effects: increasing trackdegradation and decreasing time for repairs.

� By the mid 70’s, with tonnage at 55MGT/year and expectedto go on increasing, it seemed that track maintenance wouldlimit the capacity of the system.

3.3 Remedial Measure Addressed(i) Up gradation of track continuing of Rail of 68kg/m, proper

consolidation of embankment. Improving quality of ballast andhigher ballast cushion; use of Malaysian treated sleepers andbetter quality of fasteners.

(ii) Rail Profiling by proper rail grinding machine.

(iii) Monitoring of Track tolerances: Laying standard track tolerancesand proper monitoring of the same.

(iv) Better track management system.

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3.4 ConclusionsThe up gradation of the track technology and better track managementsystem gave dramatic improvement in wear rates, lesser input formaintenance, lesser use of man hours, lesser rail failure andimprovement in track geometry.

4.0 Fortescue Railway of Western Australia

4.1 IntroductionFortescue railways of Western Australia is the world’s newest Heavy-Haul, railway which was competed in April 2008.

4.2 Historical BackgroundFortescue Mining Group was set up in Australia in 2003 to challengethe dominance of the big multi-national mining companies. Fortescue’ssubsidiary, The Pilbara Infrastructure (TPI), signed an agreement inDecember 2004 with the state of Western Australia to build and operatea 288km railway from Fortescue’s first mine from Cloud Break toPort Hedland and provide port facilities there.

4.3 Construction of the ProjectThe railways project started in November 2006, construction of theformation could not start until July 2007 as a cyclone destroyed therecently-built construction camps which had to be replaced. Thisforced Fortescue to complete the railway in less than nine months tomeet the target date.

Fortescue Railway opened on April 6 2008. It is designed to operatefour 2.8km-long 240-wagon trains a day to enable it to carry 55 milliontones a year initially. Trains are handled by two locomotives, withbanking units for the first part of the trip.

4.4 Key Design ObjectivesThere were four key design objectives for the new railway:

� Minimize the impact on the environment

� Keep the overall track length to a minimum

� Minimize adverse gradients, although this was not entirelypossible as banking locomotives are needed to push the trainsout of the mine, and

� Achieve maintenance excellence and efficiency.

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4.5 Track Structure(i) Formation was mostly on embankments using local earth but

duly treated.

(ii) Rails were imported rails from China having 68 kg per meterwith a tensile strength of 1100 Mpa

(iii) Turnout – Two types of turnout are installed on the railway:1:20 swing-nose tangential mainline turnouts designed for70km/h operation, and 1:12 rail cast manganese tangential40km/h turnouts for use in yards and sidings.

(iv) Sleepers & Ballast – Pre-stressed monoblock sleepers werelaid at intervals of 675mm. The ballast was initially laid to adepth of 150mm and then work-hardened and super-lifted to250mm.

4.6 Problems in Construction of Fortescue Railway(i) Formation: Fortescue faced a number of construction

challenges. It was difficult to produce a good formation onsome parts of the railway. There was also a lack of a suitableformation capping material. Therefore, 1% cement-stabilisedsand had to be used in some areas. The formation capping isa minimum of 200mm with 97% compaction.

(ii) Ballast: Quality of ballast also faced problems. The ballasthad to be work hardened and depth increased from 150mmto 250mm.

(iii) Rails & Turnout : Special rails had to be imported from Chinawith 68 kg per meter weight. Modern turnouts were used sothat speed could go upto 70 km/h

(iv) General : A key factor in designing the railway was to minimizeoperating and maintenance costs. Driver-only operation is thenorm with train control situated in Perth, 1600km from thePilbara.

4.7 ConclusionFortescue railway has set a new benchmark in heavy-haul railwayoperation, and no doubt other heavy-haul railways will be keeping aclose eye on Fortescue to see how 40-tonne axle load operationworks in the long term.

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5.0 Economics of Running Heavier Axle Loads & Longer Trainsin Sweden (Europe)

5.1 BackgroundThis is basically a study on the Economics of running heavier axleload and longer trains in Sweden in Europe.

Under increasing international competition, the movement of iron orefrom mines in Northern Sweden to ports in Norway and Sweden, waslooking for ways to reduce transportation costs and increasecompetitiveness.

As European railways came under increasing pressure to reduceoperating costs, and to even show a profit in their freight (goods)operations, it was only natural that they look at the costs and benefitsassociated with heavier axle loads and see if the benefits experiencedelsewhere can also be realized in the European environment.

5.2 Results of StudyThe analysis showed the following results

a) Operation of 68-wagon trains with 100 tonne load capacity (30Tonne axle load) produced a reduction of approximately 30% indirect operating costs over the base case (52 wagons of 80tonne capacity), taking into account the expected increase intrack maintenance costs as a consequence of the increase inaxle loads.

b) Assuming a “worst case” increase in track costs, savingsremained in the range of 27%.

c) The increase to 30 tonne axle loads reduces costs by about50% more than simply increasing train length, without increasingaxle loads.

d) The increase in axle loads also reduces the number of trainsthat must be operated to carry the current and future volumesof iron ore, freeing up line capacity for other traffic and allowingthe more efficient scheduling of maintenance work.

5.3 Conclusions� Based on the results of this study, the decision was made to

purchase new heavier axle load equipment, with 100 Tonnecapacity (30 Tonne axle load) and radial bogies.

� Prototype orders were also placed, with 68 trainsets of 68

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wagons each, to be ordered upon completion of acceptancetests.

6.0 Maintenance of Heavy Haul Corridor of Union PacificRailway

6.1 Introduction

A study was undertaken by AREMA of four important Heavy Haulroutes of Union Pacific Railway sometimes in 2003. Out of fourcorridors, one corridor of Heavy coal route had 80% traffic having 34to 37 tonnes axle load.

The weight of these Heavy Haul trains have been increasing year byyear and in the year 2003, there were about 35 HAL trains and eachtrain was carrying about 15,000 tones.

6.2 Track Structure: - UPRR HAL Standard Track Section

Track Structure consisted of (i) 141# Rail Section (ii) Concrete Ties(iii) 12" Ballast under Concrete Ties (iv) 18" Shoulder Ballast(v) Concrete Bridges (vi) Concrete Crossings (vii) Concrete Turnouts(viii) Moveable Point Frogs

6.3 Track Maintenance

(i) The track was being maintained mechanically with the help ofHeavy Track Machines consisting of Plasser 09-3X Tamper,Track Finishing Machine, Primary Surfacing Unit, Plasser RM80Undercutter, Loaram Rail Grinder, Harsco Switch Grinder

(ii) The rail joints were mostly welded by Plasser Flash Butt Welderand only at few locations the welding at site was done by ThermitWelding

(iii) Ultrasonic inspection of Track was done with the help of MobileRail Testing Trolley.

(iv) Rail detection was done with the help of Rail Testing Cars.

(v) Trench Drains – Special Ballast filled Trench Drains were providedas shown in the Picture. (See Figure 6.1)

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Fig. 6.1 Ballast Filled Trench drains

The benefits of the Trench Drains were (i) Removes Water FromSubgrade (ii) Opportunity to Observe Subgrade (iii) MinimalInterruptions to Train Operation

6.4 Problems of Heavy Axle Load Track and RemedialMeasures.

(i) Failure of Glued Bonded Joint : The problem arises becauseeither the insulation gets broken or there is failure of glue whichbonds the joint.

(ii) Failure of Concrete Tie Plate : The tie plate gets damagedor even broken particularly on receiving end. This happensbecause of the heavier loading conditions. The solution liesin providing second generation TIE, which gives about 25%less stress on the plates (Fig 6.2)

Fig. 2 Second Generation Tie Plate

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(iii) Failure of Concrete Ties on Bridges : The concrete ties gotdamaged due to Heavy Axle Loads. Cracks developed on theTies particularly on bridges as seen in the picture. (Fig. 6.3)

Fig. 3 Cracked Concrete Ties on concrete bridge for HAL line

The remedial measure lies on providing the following:

� 100-ft. Long, 8" Hot Mix Asphalt (HMA) Underlayment

� 100-ft. Long, 8" Geocell Subballast Reinforcement.

� Cement Stabilized Backfill, 6.75 ft. Deep, 10 ft. Long with a 2:1Taper, Upward

� Standard Track Construction (12" ballast on compactedembankment)

(iv) Failure of rubber pads (Fig. 6.4) : There is also the possibilityof rubber pads failure as shown in the picture.

Fig. 6.4 Damage of Rubber Pads

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The solution lies in providing ‘New Three Part Pad’ (Fig. 6.5)

Fig. 6.5 New Three Part Pad

(v) Spalling on Rails: The spalling on rails takes place particularlyon curves (Fig. 6.6)

Fig. 6.6 Spalling on Rails

The solution lies in providing premium quality steel for rails havingsuperior wear characteristics.

7.0 American Rail Roads – Track Transition Solutions for HeavyAxle Loads Service

7.1 Introduction: Track transition areas such as bridge approaches,level crossings, and special track work can become significantmaintenance problems under heavy axle load traffic and can generateimpacts that contribute to accelerated degradation and shortenedcomponent life.

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The Transportation Technology Center, Inc. (TTCI), Pueblo, Colorado,a subsidiary of the Association of American Railroads (AAR), madea study and evaluated the effectiveness of currently accepted tracktransition designs.

Some of the important findings of this study are discussed insubsequent pages.

7.2 Main Problems in Track Transition AreasOne important problem in mainline track is the performance of tracktransition such as those found at bridge approaches, level crossings,and special trackwork. In these locations, the track structure, andoften the load environment, changes significantly over a very shortdistance. This can result in increased dynamic loading and neededtrack maintenance.

Problems at a track transition are can be divided into three categories:

(i) Differential Settlement: Differential settlement is where twosegments of track settle at different rates, such as the bridge tobridge approach track transition. Railroad bridges are built ondeep foundations and are relatively immune to subgradesettlement. In contrast, the approach consists of fill and has alarge amount of settlement compared with the bridge structure.The running surface deviation that develops in this situation cancontribute to high dynamic loads as high as three times thestatic wheel load.

(ii) Track Stiffness Case : The track stiffness case is the abruptstiffness change that occurs in the track transition.

One typical case is of a concrete span ballasted deck bridgewith concrete ties can have a very high track modulus comparedwith the surrounding track. The abrupt stiffness change by itselfdoes not contribute to higher dynamic loads, but coupled with arunning surface deviation can induce high impact loads.

(iii) Track Damping Case: The track damping case addressesenergy dissipation of high dynamic loads. Track damping differsbetween different track structures at a track transition. Forexample, on a bridge approach energy is dissipated through thetrack structure, subgrade, and surrounding ground. On a bridgestructure, some energy is dissipated in the ballast layer, butmuch of the energy can reach the bridge structure. It is important

2. 13

to understand the types of impacts and design damping into thetrack structure to alleviate potential damage. Two types of impactsviz. wheel dynamic impact & wheel balance are generated attrack transition with running surface defects, wheel impact andwheel bounce.

7.3 Research StudiesResearch studies are being done for all three Parameters viz.settlement, stiffness, and dampening track transition casesmentioned earlier. Apart from theoretical work, predictive tools arebeing developed to aid in designing effective track transitions. Fieldevaluations are being conducted to monitor the effectiveness of tracktransitions in place.

As far as theoretical work is concerned, parametric studies havebeen done using NUCARS™ and Geotrack™ software to look at theeffects of track damping and stiffness. A differential settlement modelhas been developed to help predict settlement for different trackstructures.

The research studies have been done under the following main topics(i) Geotrack™ study (ii) NUCARS™ study (iii) Differential settlementmodel (iv) Laboratory & field testing (v) Fast & revenue servicetesting for bridge approach transitions (vi) Study for special trackwork transitions

7.4 Conclusions(i) Theoretical work suggests there are opportunities to improveperformance of track transition areas. NUCARS™ modeling suggeststhat adding damping to a track structure can improve impactattenuation by up to 30 percent. Different ways to add damping tothe track are being investigated. Rail seat pads, tie plate pads, ballastmats, and subgrade treatments are all potential solutions. Sometypical damping pads are given in (fig. 7.7)

(ii) The parametric study using Geotrack™ suggests the best methodfor raising approach track stiffness is subgrade treatment. The studyalso suggests the best method of reducing bridge track stiffness isto alter tie to pad properties.

(iii) Field testing indicated that different tie materials can provideeffective ways to improve the track stiffness transition. Plastic tiesinstalled on bridges in concrete tie territory have been successful ineliminating the stiffness differential for the first 240 MGT.

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Fig. 7.7 Various Type of Damping ToolsConcrete ties with rubber pads also helped in lowering themodulus below that of the approach and increasing the dampingproperties of the bridge structure. Thus, this method appears capableof addressing both track stiffness and damping issues and is apromising solution because the desired properties can be designedinto the pads.

(iv) A good number of predictive tools is being developed toprovide a way to design effective track transitions to address stiffness,damping, and differential settlement. Field testing has proved thatthese are effective ways to address each of these issues.

8.0 Effect of Heavy Axle Load on Bonded Insulation Joint-Research Study by TTCI (American Rail Board)8.1 IntroductionHeavy Axle Load (HAL) coal traffic, with higher speeds and highertraffic densities, places a significant performance demand on bondedinsulated rail joints (bonded IJs) (Fig. 8.8)

Fig. 8.8 Typical main line bonded Insulation joint

Rail Seat Pad The Plate Pad

Under Tie PadBallast Mat

2. 15

While bonded Insulated Joint (IJ) are essential as an operationalneed they also introduce weak points in the track which causeincreased maintenance and service disruptions. Bonded IJs are alsoa potential safety risk. These thing get further aggravated when HeavyAxle Load pass on these joints.

It may be brought out that Bonded IJ performance on heavy haul coalroutes has significantly declined as the load environment has becomemore servere. Today, bonded IJ service life may be as short as 200MGT. This short service life is lower than virtually all other runningsurface components including turnout frogs and switch points.

On high tonnage routes, bonded IJs may be replaced within as littleas 12 to 18 months with direct costs of thousands of dollars (Rupees)per mile per year. Indirect costs such as crew labor and scheduledisruption due to train delay can be higher, especially on lines withfull capacity. With such short service lives, the economics ofdeveloping a longer lived bonded IJ are compelling and is a technicalrequirement. In order to critically examine the design of existingbonded insulation joints, their failure modes, recent design evaluation,a research study was done by the Transportation Technology Centre,Inc., (TTCI), Pueblo, Colorado, a wholly owned subsidiary of theAssociation of American Railroads (AAR) in collaboration with someother organization.

8.2 Service Life of Bonded Insulation JointsThe research studies taken on specific projects brought out thatfollowing important factors adversely affect service life of these jointsdue to Heavy Axle Loads.

� Higher average wheel loads from larger capacity cars

� Higher dynamic loads from higher speeds and a stiffer trackstructure.

� Higher longitudinal forces from elimination of other rail jointsand better rail anchoring.

� Higher traffic density which reduces opportunities to performbonded IJ maintenance activities such a surfacing and runningsurface flow grinding The service life of a bonded Insulated Jointsclassified differently from many other track components becauseit can deteriorate and fail rapidly.

2. 16

8.3 Effect of Axle Load, Dynamic Load, and Traffic VolumesThe effects of static load (axle load), dynamic load, and traffic ratesare interwoven in evaluating bonded IJ performance on HAL routes.As the railways have increased car capacity, they have also Increasedtraffic rates, Raised train speeds, Increased track stiffness, Increasedthe tensile stress in the rail.

With these conditions in mind, it was perceived that the heavier loadsand higher speeds were generating more mechanical componentdefects. The effect of all three factors (static load, dynamic load, andtraffic rates) have been significant in raising the severity of the serviceenvironment experienced by track components such as bonded IJs.

8.4 Failure Mode AnalysisIn order to better understand failure mechanisms, a sample of 20 IJsremoved from revenue service was collected and examined by TTCI.The joints were from lines that carry coal traffic predominantly in 286Kip cars.

Some of the important results which were arrived after examinationof the sample were :

(i) Many joints have more than one defect.

(ii) There are several common modes that limit service life for bondedIJs in HAL service. Some of these are related to quality controlissues in components and assembly.

There are also service life-reducing aspects related to the designand capacity of the joint. These occur with structural aspects ofthe joint or components within the joint. These situations beginwith the joint becoming a running surface discontinuity. Thisdiscontinuity generates dynamic loads at the joint which damagethe foundation. Due to lower stiffness of joint, the deflectionbecomes significantly larger than deflections typically found insurrounding track.

(iii) Cause of the poor foundation condition in this case is the dynamicloading generated by the running surface discontinuity of the IJ.The combination of high dynamic forces and larger deflectionsat the IJ cause the foundation to fail here before it does in opentrack. The foundation condition causes cracking in the glue orepoxy at the top-centre of the joint bar to rail interface.

2. 17

(iv) The weakened epoxy bond allows moisture intrusion and largerdeflections. Due to this, the situation become of a disassembledbonded IJ with glue debonding and water intrusion. As the gluedebonds, the joints becomes subjected to “pull-apart” becauseof the longitudinal forces in the rails. “Pull-apart” damagesinsulating components such as thimbles and end posts as wellas mechanical joint components such as bars and bolts. (Fig.8.9)

Fig. 8.9 Typical failure of Glued bonded joint

8.5 Conclusions

(i) Improving Performance of Insulated Joints

(a) Improving the performance of bonded IJs can beaccomplished by improving any of the weaknesses incurrent designs, maintenance and operations. The effortsto improve the design is based on the following points:

(i) Reducing deflections

(ii) Reducing component relative movement

(iii) Increasing the strength of failure prone components.

(b) Reducing DeflectionsSeveral methods have proven to be effective at reducingmaximum bonded IJ deflections. These include:

(i) Supported bonded IJs(ii) Multiple tie plates

2. 18

(iii) Longer Joint bars(iv) Larger (cross section) joint bars.

(ii) Performance Requirements of Bonded Insulation JointsThe research studies have suggested draft performance requirementof Insulated Joints. These requirements are a first draft based on theobserved problems with existing bonded IJS in HAL service and theservice environment measurements made. These have beententatively laid down by American Rail-Roads.

(iii) Advanced Design for Bonded Insulation Joint

Based on the research studies, a design has been developed basedon observation of current designs, analysis and modeling work, andthe requirements of the draft performance guidelines. This designwill have the following features:

� Reduce bonded IJ-caused dynamic loads with less running surfaceand more damping running surface design from AAR FrogLongitudinal Profile

� More damping: Mitigates effects of dynamic loads

� Lower Deflections: by having Foundation with larger bearing areaon ties and ballast, Continuous support,

� Components: having Stronger insulator and more environmentallystable epoxy

� Assembly with Improved rail and bar surface preparation: toeliminate surface contamination.

9.0 Summary and Conclusions

9.1 Track Defects on Account of Heavy Axle Loads

(i) Formation� Problem of settlement, slippage and even failure.� Special problems in yielding formation & bad quality soil.

(ii) Rails� 13Defects develop in rail; cracked Rails� Develops high contact stresses between rail & wheel

causing wheel burn, wheel scabbing.� Rapid rail wear; Excessive wear of rail on curves.

2. 19

� Scabbing of rail is more prominent particularly on steepgradients.

(iii) SleepersWooden Sleepers: Fast deterioration causing poor trackgeometry; lesser sleeper life.

Concrete Sleepers: Generally satisfactory but getsdamaged, cracked or even broken in special locations likebridge approaches, on bridges and such other locations.

(iv) Ballast� Ballast not of desirable quality; lesser ballast cushion.

� Pulverization of ballast & clogging of shoulder ballast onaccount of heavier axle loads & dropping from the wagons.

(v) Fittings & Fastenings� Fastening get loose very fast and thereby effecting track

geometry.

� Rubber pads get damaged early. Heavy crushing of rubberpads.

� Glued Insulated Joint start failing because either insulationgets broken or failure of glue which bonds the joints.

� Short Service life of bonded Insulation joint which issometimes as short as 12 to 18 months; This is almostthe lowest than possibly all other surface components.

(vi) Points & Crossing� Quick wear, frequent renewal necessary.

� Breakage of CMS crossing at few locations.

� Lesser speed effecting adversely the traffic output.

vii) Track Maintenance

� Track geometry gets deteriorated very early due to heavyloads.

� Existing maintenance system may not be able to cope upwith the increase in work load due to heavy axle load &allied problems.

� Increase in weld failures specially of thermit welded joints.

2. 20

(viii) Bridges� Signs of distress on some of the bridges resulting in cracks

& deterioration of other bridge components. Sleepers getcracked on bridges in some cases.

(ix) Track Transition areas (Bridge approaches, LevelCrossings & Special Track Works)

� Due to differential settlement, extra track stiffness anddifferential damping Track Components gets damaged quiteearly.

� Increased dynamic loading & need for extra trackmaintenance.

9.2 Conclusion & Suggested Remedial Measures(i) General� The operation of heavy axle load trains is a economic and

technical necessity & as such Heavy Haul trains todayexist in most of the developed Railways of the World.

(ii) Formation� Soil stabilization by proper mechanical means during

construction.

� In case soil is not good, soil treatment of top capping soilshould be done. Refer case of Fortescue Railway of North-West Australia where 1% cement stabilization was doneof top 200 mm soil and with 97% compaction.

� Special treatment of formation/back fill to be done onbridges.

� Yielding formation & poor quality of soil require specialtreatment. In some situations, even provision of Ballastfilled Trench drains may help as done in case of UnionPacific Railway (See Figure 6.1)

(iii) Rails� Up to 25 tones axle load, 60 kg 90 UTS rails sufficient; For

higher axle loads, special heavy rails to be procured.

� It may be brought out that as per survey carried by JRP-2initiated by UIC there is certain relationship between railsection & axle load (See Fig.10.10) 60 kg rail section wouldsuffice for an axle load up to 25 tonnes.

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� Rail Grinding Machine: Reprofiling to be done by RailGrinding machine for prolonging rail life as well to preventdefects in rail head.

� Mechanised USFD Testing of rails: Use improved andmechanized USFD technology (Spurt cars etc.) for testingof rails.

� Roll longer rails to reduce welds and also to improveperformance.

(iv) Sleepers� Mono block PRC sleepers quite satisfactory in ordinary

situations.

� At special locations provide Special sleepers like “SecondGeneration Tie” to reduce stress on plates as done onUnion Pacific Railway (See Fig 6.2).

(v) Ballast� Better quality of ballast with full ballast cushion of 25 cm

to 30 cm. If necessary, work hardening of ballast to bedone to improve quality of ballast.

� More frequent deep screening of ballast to be done bymechanized methods.

Survey of current practices, carried out by JRP-2, intiatedby World Executive Council of UIC indicates the following

relationship between Rail Section and Axle Load :

2. 22

(vi) Fittings & Fastenings� Quality of fitting & fastening and rubber pads to be improved.

� Develop better design of rail pads like ‘Three Point Pad’ asdone by Union Pacific Railway (See Fig 6.5)

� Bonded Insulated Joints are worst effected & their designto be further improved by looking after the problems incurrent design, maintenance & operation. The bondedinsulation joint should be designed based on standard.‘Performance Requirement’ for HAL Service and particularlyensuring reduced dynamic loads, lower defectors & strongerinsulator & other components.

(vii) Points & Crossing� To be modernized to cater for higher speeds of 75 kmph to

100 kmph. Refer Swing Nose Turnouts 1:20 designed for70 kmph for Fortescue Railways of Western Australia.

(viii) Track Maintenance� Complete Track mechanization of track maintenance &

track renewal works.

� Fixing proper tolerance for HAL trains & better Monitoringof track tolerances.

(ix) Bridges� Bridges should be designed for heavier loading. Quality of

bridge construction require to be improved.

� As cracks develop sometimes in concrete ties on bridges,it is necessary that sub-base of bridge require to bestrengthened by making it compacted embankment. Thesub-base can be upgraded by providing hot mix as underlayment, Geocell sub-ballast Reinforcement, cementstabilized back fill & 12" ballast

(x) Special Case for Track Transition Areas : (BridgeApproaches, Level Crossings & Spl. Track work)

� Improving Track structure for track transition area such asBridge approaches, level crossing & special track works.

� The studies suggest that proper damping devices on trackcan improve track impact by 30%. Provide special dampingdevices like Rail seat pads, Tie Plate pads Ballast pads

2. 23

etc to improve track performance. (See Fig 7.7)

� Development of Predictive tools to provide a way to designeffective Track Transitions to address stiffness, damping& differential settlement.

� Installation of Plastic ties bridges in concrete Tie Territorycan be successful in eliminating the stiffness differential.

� Concrete Ties with rubber pads can help in lowering trackstiffers & damping issues and as such improve trackperformance.

(xi) Track Management cum Information SystemTo introduce better track management cum informationsystem so that monitoring of track maintenance & otheraspects of track management can be supervised/controlled.

10.0 Use of Experience of World Railways by Indian RailwaysSystem to Run Heavy Axle Load Trains

10.1 Introduction: Indian Railway took a bold decision in the year2001-02 to run heavier axle load than existing axle load of 20.32tonnes in an effort to enhance the traffic capacity of Railways tohandle the increased traffic as well as to increase its financial viability

A pilot project of (CC+8+2) with an axle load of 22.9 tonnes wasimplemented on the 20 routes initially and later on 14 more routesadded after the positive feed back from the different railways, themajor routes are in the South Eastern Railway, East Coast Railway,SEC Railway and Eastern Railway. Presently CC+6+2T is in operationnearly on 26000 route kms and CC+8+2T on 5000 kms.

The experience gained by IR in a short span of few years was almoston similar lines as experience gained by other railway system of theworld. Heavy wear & tear of rails, cracked rails, more frequent renewalof fittings & fastenings such as Pandrol clips, Insulation joints, Rubberpads, poor track geometry due to axle loads, problems on bridgesare some of the typical examples.

10.2 Remedial Measures Suggested: The remedial measuressuggested to mitigate the effect of heavier axle load based onexperience gained by different Railways have been brought out inpara 9.2

2. 24

These remedial measures are quite detailed & some of them veryspecial and these can be of immense use to Indian Railways forrunning of heavier axle loads. Indian Railways have already nominatedsome lines for running of heavier axle load of 25 tonnes (called feederroutes). Dedicated freight corridor with an axle load of 30 tonneshave been planned on the golden quadrilateral out of which twocorridors (Mumbai & Howrah corridors) are already sanctioned. Thework on these projects is likely to be started shortly.

10.3 Concluding RemarksIt is felt that experience of more than 3 decades gained by differentrailway system of the world may be of immense use to IndianRailways for running of heavy axle loads.

11.0 Bibliography1. Rail Road Track mechanics & Technology by Amold D. Kher,

PERGAMON Press, New Delhi (1984 )

2. Track Technology- Proceedings of a conference organized byInstitution of civil engineers held at University of Notingham (1984)

3. Indian Railway Track by M.M. Agarwal - Prabha & Co., New Delhi(2009)

4. The impact of Track technology on Heavy Haul operations-WR ….Lecture in conference by I.C.E. held at University of Notingham(2006)

5. Proceedings of Ist International Heavy Haul conference held inWestern Australian (1978)

6. Proceedings of 9th International Heavy Haul Conference held inShanghai (2008).

7. Turnround of Indian Railway by increasing axle load-A joint studyby IIM Ahmedabad & Railway Staff College, Vadodra (July 2006)

8. Heavy Axle load maintenance on Union Pacific Railway-A report byAREMA (2004)

9. Fortescue New Line raises the bar for Heavy Haul-InternationalRailway Journal Volume 49, issue of (September 2009)

10. Wheel-rail interface-Transnet gets to grips with wheel wear data-New system transformation wheel–rail Interface –InternationalRailway Journal-Volume 49, Issue of September 2009.

11. Introduction of Heavy axle load in Europe- The economics of 30Tonne axle load operations in the main stress by Allan M.Zarembskir

2. 25

of ZETA-TECH of USA & Bjorm Paulsson Banverket Bortange,Sweden (2006)

12. Introduction of ‘Heavy axle load on IR-Paper by Rakesh Chopra &H.L. Suthar (2007)

13. Review of works involved for running of 25 Tone axle load on IR byMahavir Singh Dy CECTS WR & K.L. Meena, DyCE/NWR (IRICENPune)

14. Technical paper on increase of Axle load on IR-Track Designconcepts-RDSO Lucknow.

15. Bonded Insulated joint performance in main line track by D. David-Technology Digest TD04-006, TTCI, Pubelo, Colorado-May-2004.

16. Concrete Tie design for heavy axle load application-by G. Gemeiner-AREMA Annual Conference 2004.

* * *

2.26

Effect of Higher Axle Load on Bridges in SouthWestern Railway

R.S.Dubey*Ramesh Kambli**

T.A. Nandakumar***

* CBE/South Western Raillway**Dy.CE/Bridge/South Western Raillway***ADEN/Bridge/South Western Raillway

Synopsis: To enhance the throughput to meet traffic demands ofthe nation, Railway Board permitted operation of CC+8+2 (Axle Load22.82 t) and CC+6+2 (Axle load 22.32 t). As a pilot project it wasintroduced in S.W. Railway on identified routes. This paper dealswith the experience of higher axle load on Bridges on S.W. Railway.

1.0 IntroductionIn developing economy, growing demands of transportation is one ofthe most important features. Railway being the bulk and Largesttransporter, is playing important role in this. To meet this challenge,Railway had following options.

1) Increase the number of trains

2) Increase the number of wagons in train formation

3) Increase load carrying capacity of existing rolling stocks/wagons

4) Increase number of lines

5) A separate freight corridor

To begin with Indian Railways decided to permit heaver axle load onthe existing system. In line with above objectives and routes wereidentified where heavier axle loads such as CC+6+2 and CC+8+2could be run. Pilot projects were accordingly sanctioned by RailwayBoard to monitor the performance of rolling stock, track and bridges.

2.0 Higher Axle Load Train Operation On SWRSouth Western Railway consists of 3 divisions viz, Hubli, Bangaloreand Mysore divisions. Total No of bridges available on these divisions

2.27

including minor, major and important bridges are listed as below.

Division Total No. ofbridges available

Bangalore 2681

Mysore 2249

Hubli 1900

Total 6830

Total No. of bridges available on the identified routes are listed below

S. Route nominated for No. of No. of No.of No. of TotalN. Higher axle load arch steel concrete Miscell- Number

operation bridges bridges (RCC/PSC) aneous ofbridges bridges bridges

1 Bellary-Hospet- 132 93 387 299 911Hubli-Londa-Vasco-Da-Gama

2 Toranagallu- 0 7 25 13 45Ranajitpura

3 Hospet-Gunda 1 2 107 29 139Road-Swamihalli

4 Gunda Road-Kotturu 0 5 107 6 118

5 Bellary-Raydurga 4 13 152 126 295-Chikjajur

6 Ammasandra- 201 32 113 89 435Arasikere-Birur-Chikjajur-Harihar-Hubli

7 Arasikere- 13 120 178 441 752Hassan-Mangalore

TOTAL 351 272 1069 1003 2695

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RDSO vide letter No. CBS/Golden/Q/Strength dtd. 20/3/2007 hasissued guidelines for running of CC+6+2T (22.32 T) and CC+8+2T(22.82 T) axle load operation.

i. RDSO has checked the superstructure of standard spans (6.1m,9.15m, 12.2m, 18.3m, 24.4m, 30.5m, 45.7m, 61.0m and 76.2m - allclear spans) of bridges for 60 Kmph speed for CC+6+2T and CC+8+2T axle load and found that superstructure of all standard spansdesigned to BGML loading standard , RBG loading standard andMBG loading standard are fit for 60 Kmph speed (suitability ofsuperstructure of standard spans has been checked for height ofC.G. of wagon from rail level not exceeding 1830 mm).

ii. RDSO has checked the bearings of standard spans of bridgesfor CC+6+2 T and CC+8+2 T axle load and observations are as below:-

a) Bearings of standard spans designed for MBG loadings are fitfor running of CC+6+2 T and CC+8+2 T axle load BOXN wagonwith coupled WDG 4 and coupled WAG 9 locomotives.

b) In case, the bearings designed for BGML/RBG loading standardshave been replaced in accordance with RDSO letter of even no.dtd. 30-12-2004 summarized in Annex-6, then bearings are fitfor running of CC+6+2 T and CC+8+2 T axle load BOXN wagon.

c) In case, the bearings designed for BGML/RBG loading standardshave not been replaced in accordance with RDSO letter of evenno. dtd. 30-12-2004 summarized in Annex-6, then Zonal Railwaysshould either replace existing bearings as indicated above orstrengthen the bearings as per Annex-6 for restricted speed of60 Kmph.

iii. Zonal Railways are required to check the suitability of bridgesfor CC+6+2T and CC+8+2T axle load, as below:-

a) Superstructure of non-standard spans including Arch Bridgesetc.

b) Bearings of non-standard spans and Substructures of all thebridges.

Longitudinal forces are to be taken as given in Annex-2 of 4(depending on the electric or diesel traction). These longitudinalforces are without considering dispersion. As per correction slip32 to IRS Bridge Rules issued vide RDSO letter No. CBS/PBR

2.29

dt. 21/23-06-05 (copy enclosed as Annex-7), dispersion oflongitudinal forces should also be considered while checkingsuitability of existing bridges. However while considering thedispersions of longitudinal forces the conditions given as perclause no. 2.8.3 2 of IRS Bridge Rules should be met with.

If found unsafe, then details of longitudinal forces with limitingthe tractive effort to 30 T per loco, as given in Annex-3 or 5(depending on the electric or diesel traction) may be used andaccordingly position should be prepared.

c) One time inspection of all bearings apart from schedule inspectionfor their proper functioning and bed block for their soundnessshould be done.

d) Following locations/members are to be monitored as beingcritical from fatigue considerations.

� Connection of cross girder with stringer.

� Outstanding leg of the top compression flange of the strings at its junction with web rivet.

� Rivets of splice joints of bottom flange in plate girders.

e) Physical conditions of bridges are to be certified by Zonal Railways.

f) Sample bridges (representing type and span of those availableon the routes) and vulnerable bridges, shall be selected forinstrumentation for monitoring the effects of increased longitudinalforces and higher axle loads on the bridge components i.e.foundations, piers and abutments, bearings and superstructure.

Instrumentation shall be with respect to measurement of settlementof foundations, tilting of piers/abutments, loads on bearings,deflections and stresses at critical points. Change in dynamicparameters may be monitored for quick evaluation. (Ref: Rly. Bd’sletter No. 2005/CE-II/TS/7 Pt dtd. 09-05-06).

Accordingly, following action was taken by S.W. Railway –

I. Checking the suitability of bridges for CC+6+2T and CC+8+2Taxle load, the superstructure of non-standard spans including ArchBridges.

a) Superstructure of nonstandard spans

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Following is the list of non-standard bridges in the section (BAY –UBL – LD – VSG section)

Number of Non-standard Span Bridges

Section Major Minor Total

UBL-LD 0 19 19

LD-VSG 13 44 57

UBL-BAY 6 12 18

HPT-SMLI 2 27 29

TNGL-RNGP 1 2 3

b) Arch Bridges

In the BAY – VSG route the distribution of Arch Bridge is given below:-

Section Total No. of Arch BridgesUBL - LD 21

LD - VSG 66

UBL - GDG 4

GDG - HPT 6

GDG - SMLI 1

Total 98

All the Arch Bridges, both major and minor were examined by Ring1.5 software.This software has been developed by Sheffield UniversityUK. It provides very useful tool for first level assessment of arch bridge.It is used as on aid to decision making regarding identifying criticalbridges, frequency of inspections and strengthening required.

II Bearings of non-standard spans and substructure of all the bridges.

a) The bearings of all non standard spans were checked and thebearings of the following bridge is strengthened by providing twoadditional anchor bolts.

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Sl. Br. Location Between Span Type of Type ofNo. No. stations bridge Sub structure

1 139A HPT yard BAY–GDG 1x30.48m Girder RCC

b) On checking the sub-structure of all the bridges, the tractiveeffort had to be restricted to 30 T for the following bridges:-

Sl. Br. Location Between Span Type of Type ofNo.No. stations bridge Sub structure

1 47 Km 24/7-25/1 SMLI - HPT 3x12.20m Girder Stone Masonry

2 139A HPT yard BAY - GDG 1x30.48m Girder RCC

3 3 Km 1/0-1 TNGL- NHT 2x19.40m+ Through Granite

1x12.19m Girder Masonry

4 39 Km 19/10-11 GDJ - SMLI 3x12.20m Girder Stone Masonry

5 157 Km 153/8-9 BAY - HPT 1x12.20m Girder Stone Masonry

6 184 Km 167/9-168/0 BAY - HPT 1x12.20m Composite Stone Masonry

Girder

7 200 Km 174/0-1 BAY - HPT 8x12.20m Girder Stone Masonry

8 204 Km 176/10-11 BAY - HPT 1x12.20m Girder Stone Masonry

9 206 Km 177/13-14 BAY - HPT 4x12.20m Girder Stone Masonry

10 240 Km 194/8-9 BAY - HPT 2x12.20m Girder Stone Masonry

11 243 Km 197/6-7 BAY - HPT 3x12.20m Girder Stone Masonry

These bridges were proposed in the Works Programme 2007-08 andgot sanctioned for strengthening.

Out of 11 bridges, strengthening of 10 bridges is completed and workis in progress for Br. No. 200.

Inspection of all the bearings from scheduled inspections for theirproper functioning and bed block for their soundness.

Apart from the scheduled inspections, all the bearings are inspectedfor their proper functioning every quarters and bed block for theirsoundness.

So far no adverse effect has been noticed.

2.32

c) Problems in the Bed blocks of bridges in Sakleshpur-Subramanyaroad (HASSAN- MANGALORE SECTION)Sakleshpur-Subramanya road (HASSAN- MANGALORE SECTION)is a critical ghat section of Mysore Division where cracks in piersand pier bed blocks have been notices in some of the bridges. Thesection was opened after Gauge conversion for Goods traffic on andfor passenger traffic on. The goods traffic consists of iron ore rakesof CC, CC+4 capacity

Salient Features of SKLR - SBHR Ghat Section:

• Section length of 55 km passing through Western Ghats

• There are total 241 bridges in this section, out of which 84 nos. are girder bridges

• Number of tunnels are 57. Total length of tunnels is 10970m.

• Number of block stations is 4.

• The ruling gradient is 1 in 50.

• Maximum degree of curve is 8o, total length of curves inGhat section is 33.98 km i.e. 62%.

During the inspection February 2008 of bridges, it was noticed thatthere are some bed blocks in the SKLR- SBHR ghat section whichhave been crushed. The photos of some crushed bed blocks are asbelow:

BR 184 at KM 56/300-400 BR 184 at KM 56/300-400Pier No.1 span 1 LH Pier No.1 span 1 LH

SBHR end 2 SBHR end

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BR 190 at KM 57/00-100 BR 190 at KM 57/00-100Pier No.1 span 2 LH Pier No.1 span 2 RH

SKLR end SKLR end

Br 255 at KM 71/ Br 255 at KM 71/900900-72/100 Pier No.2 -72/100 Pier No.2 span 2 LH S BHR end span 2 RH SBHR end

The bed blocks of following bridges have been crushed.

Bridge Location Span Superstructure Bed blocks location

No.

184 56/300-400 12.20 x 1+ Rivetted Plate P1 (LHS & RHS)

18.30 x 1+ Girder P2 (LHS & RHS)

12.20 x 1 (RIVTPG)

190 57/0-100 12.20 x 1+ RIVTPG P1 (LHS & RHS)

9.15 x 1+ P2 (LHS & RHS)

18.30 x 1

248 70/200-300 12.20 x 1+ RIVTPG P1 (LHS & RHS)

24.40 x 1+ P2 (LHS & RHS)

12.20 x 1

2.34

255 71/900-72/000 12.20 x 2+ RIVTPG P2 (LHS & RHS)

18.30 x 2+ P4 (LHS)

12.20 x 1

273 76/300-400 12.20 x 1+ RIVTPG P1(RHS)

18.30 x 1+

12.20 x 1

165 52/0-100 12.20 x 1+ RIVTPG P1(RHS)

18.30 x 3+

12.20 x 1

227 66/500-600 12.20 x 1+ RIVTPG P1(LHS)

9.15 x 1+ P2 (LHS & RHS)

12.20 x 2

247 70/0-100 12.20 x 1+ RIVTPG P2(LHS & RHS)

18.30 x 1+

12.20 x 1

III Causes for Crushing of Bed BlocksAfter examination it is seen that the stepped bed blocks only crushed.The stepped bed blocks have been provided during construction onthe piers, where different types spans are existing on both sides ofthe pier. The cracks have developed below the bed plate from thepoint of holding down bolts anchored into the bed blocks which arehaving more height and due to running traffic - the bed blocks havebeen crushed and bed plate have been bent. Further, it is noticedthat these crushing of bed blocks has been observed only where thebed plates are provided at the edge of the bed blocks of high depth.

These cracked bed blocks were attended by SIKA epoxy grout whichis standing well without any problem.

IV Special InstructionsSpecial instructions were issued to check the following locations/members which are critical from fatigue considerations duringquarterly inspection

� Connection of cross girder with stringer.

� Outstanding leg of the top compression flange of the stringerat its junction with web rivet.

2.35

� Rivets connecting bottom flange angle of the stringer with webat mid span.

� Vertical members at connection with top chords.

� Rivets connecting bottom flange of cross girders with web atmid span.

� Rivets of splice joints of bottom flange in plate girders.

V Monitoring of Bridges by InstrumentationEven though there is no any visible symptoms noticed in the bridges,it can not be taken granted that the bridges are safe for runninghigher axle loads based on the theoretical calculations and visualobservations. In order to get a true assessment of adequacy of thestrength of existing bridges and to forecast their behaviour for enhancedloading in the coming years, it was decided to monitor the health ofsome selected bridges, which were critical from theoreticalconsiderations, by means of instrumentation.

Initially to begin with following 5 different types of bridges were selectedfor instrumentation

SL BR. No. Location Section Span TYPE

No.

I 139A 144 / 0-1 Gadag-Bellary 1 x 30.48 OWG

II. 3 1/ 0-1 Toranagallu- 2 x 19.4 + 1 x 12.19 Plate Girder

Ranjitpura

III. 102 34 / 14-15 Londa-Vasco 2 x 27.43 Plate Girder

IV. 28 39 / 5-6 Londa-Vasco 2 x 18.29 Arch

V. 20 46/15 - 47/1 Hubli - Hospet 5 X 9.14 Arch

In order to have a better involvement in the work, S.W. Railwayapproached to Indian Institute of Science (IISc), Bangalore which isa reputed technical institute, for carrying out the work ofinstrumentation for above 5 bridges and they had come forward totake up this work as a project work. Several meetings were conductedand preliminary investigationsre wmade to assess the efficacy of themodus operandi to be adapted for instrumentation of bridges.Subsequently, the requirement of various types of sensors and their

2.36

suitability and modus operandi was finalised by IISc, Bangalore andSWR officials.

A) Scheme of InstrumentationMethodology / scheme of instrumentation is same for all type ofbridges. Instrumentation was carried out to know/measure thedeflection at various locations, stiffness of the girders, to draw theInfluence line diagram, Dynamic augmentation factor at variousspeeds, maximum and minimum stresses developed, Max. tractiveeffort and braking forces applied as well as transferred to the bridgeapproaches, bearings and at bed block level.

Following field trials/tests were conducted at each bridge location

(1) Static load test

(2) Speed test

(3) Influence line diagram for BM and SF

(4) Measurement of longitudinal forces (with out brake binding)

(5) Measurement of Tractive effort (with brake binding)

(6) Coupling test

Following combination of test train was used for instrumentation

(1) For conducting speed trials, static load test and influence linediagram2 WDG 4 (Multi Loco) + 2 BRN loaded with 200 PSC sleeperseach + 2 BOXNEL wagons loaded to 25 T axle load with Ironore.

(2) For measuring longitudinal forces (Tractive effort and Brakingforces)2 WDG 4 Locos (Multi) + 58 BOXN wagons loaded with Iron ore+ 2 WDG 4 Loco (Multi)

In order to have a better idea, instrumentation done at bridge No. 128is explained in detail below.

2.37

� Salient Features of Arch Bridge No. 128

1. Bridge No. 128

2. Location Km 39/1 & 2

3. Section Londa – Vasco (Ghat Section)

4. Year of construction 1886

5. Gradient on bridge 1 in 37

6. No. of spans 2 x 17.7

7. Type of Arch Parabolic

8. Type of foundation open foundation

9. Type of sub-soil Hard rock

10. Type of Masonry Brick masonry

11. Arch thickness 93 cm

12. No. of arch rings 8

13. Rise 4.5 mtr

14. Abutments and piers Brick masonry

15. Width of pier at top 3400mm

16. Height of pier 3900mm

17. Bridge width 6850mm

18. Alignment In curve

19. Depth of cushion 1.0 meter

� Track Structure Over Bridge:

Rails 60 kg.

Sleepers PSC 60 Kg.

Ballast cushion Adequate

� Types of Sensors Used:The objective of the study was to understand the behaviour of theArch and to determine the safety limits of the existing bridge fromthe point of view of the proposed increase in axle load (25 T). For this

2.38

sensors as given below.

� STRAIN GAUGES, (to measure the strains for working outthe induced stresses)

� ACCELORAMETERS (to measure the accelerations)

� LVDTs (to measure the deflection)

� TILT METER (to measure the relative movement)

� TEMPARATURE GAUGES (to measure the variation intemperature during the course of test and to verify thetemperature effect)

� SEISMOGRAPH (to measure the vibrations)

In addition to above, acoustic emission test was also conductedusing 8 sensors to measure the events that occurred during the courseof testing. (For sound of crack or similar events).

Location of Sensors :Following type of sensors were fixed on arch, pier, abutment andrails

Type of Sensors Span No. 1 Span No.2 Total

Strain Gauge (Electronic type) 8 4 12

Vibrating Wire Strain Gauge 3 2 5

(Mechanical type)

Cross-Bow Accelerometer 4 - 4

B & K Accelerometer 4 - 4

LVDT (For deflection) 3 3 6

Cross-Bow Tri-axial Accelerometer 1 - 1

Tri-axial Diathrone Accelerometer 1 - 1

Tilt meter 1 - 1

Seismograph (Vibration) 1 - 1

Temperature gauge 1 - 1

Total 27 9 36

purpose the bridge was instrumented with various types of

2.39

Test train over arch bridge No. 128

Location of Sensors :

LVDTs mounted at springing level LVDT at Crown level

Electrical strain gages at crown Electrical strain gages at railweb over arch

2.40

Test train over arch bridge No. 128

B) Testing and discussions of results

1. Static Load TestThis test was conducted to study the value of stresses induced andthe deflection at crown & at springing level so as to up date themodel for numerical analysis. The results obtained from this test areco-related with the model study results and accordingly model wasup dated.

Finite element model of Masonry Arch BridgeDeflections measured during static test

Load (no. Springing Horizontal Deflections Crown vertical deflection of Span 1 Span 2 sleepers) CLR Kulem CLR Kulem CLR side Kulem side

side side side side (mm) (mm) (mm) (mm) (mm) (mm)

168+168 0.2 0.05 0.04 0.05 0.49 0.3

184+184 0.0 0.21 0.0 0.29 0.55 0.6

200+200 0.1 0.17 0.01 0.18 0.57 0.6

2.41

Values of strains measured during static test

Fig 1 Fig 2

The tangential strains in span 1 along the center line of the track areshown in Figure 1. The strains are minimum and almost zero nearthe crown and maximum near the right springing position. Figure 2shows the tangential strains along the width of the arch at the crownposition. It may be mentioned here that one micro strain correspondsto approximately 0.0018 MPa (0.018 kg/mm2) of stress in themasonry. It is seen that the strains are largest near the eccentricposition (far end of the barrel of the arch) when compared to thecentre line of rail location. Figure 3 shows the transverse strainsalong the crown for different magnitude of loading. It is seen that allthe transverse strains are tensile in nature. The maximum value of

2.42

transverse tensile strain is about 17 micro strains which correspondsto a tensile stress of about 0.00306 kg/mm2. This value is less thanthe codal permissible value of 0.011 kg/mm2 in tension.

Values of stresses measured and computed in the Static LoadTest (200 sleepers loaded on two BFR’s = 20.25tons/axle).

Sl. Descri- Actual Type Speed Stress Permissible RemarksN. ption stresses of of calculated stresses

measured stresses train from as per(kg/mm2) numerical design

(kg/mm2)1 Soffit of 0.000144 Comp. Static 0.00136 0.05375 Within

arch-Span (Ten.) (Comp.) permissible1-Crown 0.011 (Ten.) limits

2 Soffit of 0.002214 Comp. Static 0.00501 0.05375 Withinarch - (Comp.) (Comp.) permissibleSpan 1- limits1/4th Span-CR side

3 Soffit of 0.002700 Comp Static 0.003615 0.05375 Withinarch-Span1- (Comp.) (Comp.) permissible3/4th span- limitsK side

4 Springing 0.004500 Comp. Static 0.002443 0.05375 Withinlevel- (Comp.) (Comp.) permissibleSpan 1- limitsCR side

5 Springing 0.001116 Comp. Static 0.003574 0.05375 Withinlevel-Span 1, (Comp.) (Comp.) permissibleK side limits

2. Results of the Speed TestSpeed tests were conducted using both formations as mentioned atthe beginning. The formations were made to move from Castle Rockto Kulem and Kulem to Castle Rock ends with different speeds. Thespeed test using formation 2 are part of the longitudinal load tests.The objective of the speed test is to estimate the dynamicmagnification factor and to assess the dynamic characteristics ofthe bridge structure. Table 2 shows the max.values of the tangentialstresses measured at different locations of the arch across all speedcases using formation 1. It is seen that the stresses are within thecodal permissible levels.

2.43

Maximum values of Tangential Stresses Measured in theSpeed Test

Sl. Descri- Actual Type Speed Permissible Details of RemarksN. ption stresses of of stresses as deflection

measured stresses train per design (mm)(kg/mm2) (kmph) (kg/mm2)

1 Soffit of 0.00132 Ten. 30 KC 0.011 (Ten.) Stressesarch-Span 0.00207 Comp. 20 KC 0.05375 Within1 - Crown (Comp.) permissible

limits40 KC -0.1464

2 Soffit of 0.00449 Comp. 40 KC 0.05375 Not Stressesarch-Span (Comp.) measured Within1 - 1/4th permissibleSpan limits

3 Soffit of 0.00387 Comp. 20 KC 0.05375 Not Stressesarch-Span (Comp.) measured Within1 - 3/4th permissibleSpan limits

4 Springing 0.00037 Ten. 20 CK 0.011 Stresseslevel - (Ten.) WithinSpan1-CR 0.0038 Comp. 20 KC 0.05375 permissibleside (Comp.) limits

5 Springing 0.0034 Ten. 5 CK 0.011 Stresseslevel-Span (Ten.) Within1 - K side 0.00160 Comp. QS 0.05375 permissible

(Comp.) limits

6 Soffit of 0.0119 Comp. 10 CK 0.05375 Stressesarch-Span (Comp.) Within2 - 1/4th permissibleand 3/4th limitsSpan

2.44

Measured response during speed test using formation 1; the resultsof quasi-static moving load test are also shown; x-axis is normalizedto show the location of the leading wheel; CK: movement from CastleRock to Kulem.

Measured response during speed test using formation 2; x-axis isnormalized to show the location of the leading wheel; movementfrom Castle Rock to Kulem.

2.45

3. Influence Line Test ResultsDeflections measured during influence line testFollowing table gives the maximum values of deflections measuredat crown as well as at springing levels across all episodes of testing.

Springing Horizontal Deflections (in mm) Crown vertical deflection ( in mm)

Span 1 Span 2 Permissible

value

CR Kulem CR Kulem Both ends Span 1 Span 2 Permissible

side side side side value

0.10 0.17 -1.42 0.01 0.2 0.88 0.7 1.2

& 1.21

From the above table it may be seen that the horizontal displacementof the central pier at springing level is more than the limited values.This result may be due to de-lamination different types of materialsi.e. masonry pier is jacketed with RCC. This is not to be consideredas change of span.

Maximum strains measured on the two spans of the arch bridge inthe Influence line load test

Table below gives the maximum values of stresses measured acrossall episodes of testing in BM & SF test

2.46

Sl. Description Actual Type Speed Permissible Remarks

N. stresses of of stresses as measured stresses train per design(kg/mm2) (kg/mm2)

1 Soffit of arch 0.00123 Comp. Quasi 0.05375 Within

-Span 1 - Static (Comp.) permissible

Crown 0.00102 Ten. (QS) 0.011 limits

(Ten.)

2 Soffit of arch 0.00446 Comp. Quasi 0.05375 Within

- Span 1 - Static (Comp.) permissible

1/4th Span limits

(CR)

3 Soffit of arch 0.00172 Comp. Quasi 0.05375 Within

-Span 1 - 3/ 0.00606 Tensile Static (Comp.) permissible

4th span (K) 0.011(Ten.) limits

4 Springing 0.00282 Comp. Quasi 0.05375 Within

level - Span Static (Comp.) permissible

1-CR limits

5 Springing 0.00161 Comp. Quasi 0.05375 Within

level - 0.00006 Ten. Static (Comp.) permissible

Span 1, (K) 0.011 (Ten.) limits

6 Soffit of arch 0.011 Comp. Quasi 0.05375 Within

-Span 2 -3/ 0.00033 Ten. Static (Comp.) permissible

4th span (K) 0.011(Ten.) limits

4. Results of the Longitudinal Force TestsThe main objective of this test is to determine the stability of thestructure when subjected to extreme horizontal loads such as dueto braking on the bridge or accelerating from rest on the bridge

2.47

Figure above shows the maximum strains measured at different pointson the arch surface when the design train (formation 2) passed fromKulem to Castle Rock at maximum speed of 36 kmph. The force intons (as high as 34 t) acting on the rails at different points is alsoshown.

Figure below shows the maximum strains measured at different pointson the arch surface when the design train (formation - 2) passed fromCastle Rock to Kulem at maximum speed of 20 kmph with dynamicbrake applied in the active WDG4s with the first axle of the leadingWDG4 in the middle of span 1.

2.48

Following table gives the values of Horizontal Forces transferred tothe Rails in Longitudinal Load Test

Test Type Tractive Force Force at Force transferred to rails (T) Remarksapplied by Loco. Coupler as On rails in On rails(As shown in the measured Approach over Bridgeloco screen of (Tons) (2 Rails)WDG4) (T)

Coupler Test - 52.4T X 3=156* 89.06 94.12 35.56 Maxi-Design train - first mumaxle of third WDG4 valuesat right springing reported(CR) of span 1 and are ataccelerating with differentfull tractive effort time

Design Train from 53.2 X 3 = 159.6 *Not 109.36 46.99 instan-Kulem to CR at measured ces and36 kmp should

Design Train, third 52.4 X 3 = 157.2 *Not 138.44 134.76 not beWDG4 first axle at measured algebraic-K-side springing of ally addedSpan 2 andaccelerating at fulltractive effort

Design Train, third 52.6 X 3 = 157.8 *Not 95.08 32.35WDG4 first axle at measuredmid-span of Span1 and acceleratingat full tractive effort

Design Train from 25.6 X 3 = 76.8 *Not 123.3 44.06CR to Kulem at measured20kmph withdynamic brake

Design Train from 53.6 X 3 = 160.8 *Not 95.79 40.09K to CR at 20 measuredkmph with servicebrake

Brake-binding 53.2 X 3 = 159.6 Not 45.61 30.3Test measured

2.49

Similarly following table gives the maximum values of measuredtangential stresses and displacements in the Longitudinal Test

Sl. Description Actual Type Speed Permissible RemarksN. stresses of of train stresses

(kg/mm2) stresses (kmph) (kg/mm2)1 Soffit of arch 0.00199 Ten 20 0.011 (Ten.) Within

-Span 1 - 0.00308 Comp. 5 0.053 permissibleCrown (Comp.) limits

2 Soffit of arch - 0.00568 Comp. 5 0.053 WithinSpan 1 - (Comp.) permissible1/4th Span 0.00395 Ten. Accele- 0.011 limits(CR side) ration (Ten.)

3 Soffit of arch - 0.00310 Comp. 20 0.053 (Comp.) WithinSpan 1-3/4th 0.0038 Ten. Accele- permissibleSpan (K side) ration 0.011 (Ten.) limits

3 Springing 0.0034 Ten. Accele- 0.011 Within level-Span 1 ration (Ten.) permissible(CR side) 0.00439 Comp. 36 0.053 limits

(Comp.)4 Springing 0.0304 Ten. Brake 0.011 Codal

level-Span 1 binding (Ten.) clause(K side) 0.0099 Comp. Brake 0.053 violated in

binding (Comp.) tension5 Soffit of arch - 0.0123 Comp. 30 CK 0.053 Within

Span 2 - (Comp.) permissible3/4th Span 0.0102 Ten. Accele- 0.011 limits(K side) ration (Ten.)

C) Comparision of instrumentation results with ring 1.5 softwareresults : Analysis of the arch bridge was carried out using RING 1.5software. Loading considered as MBG-1987 and also 2 WDG4 locowith 2 Nos BOXNEL loaded to 25 T axle load. Critical load factor isachieved as 2.76 when the compressive strength is restricted to 20N/mm2 against the observed compressive strength of the masonryas 40 N/mm2.

2.50

The mean normal stresses calculated as per the software comes to5.4 N/ mm2 and 0.536 N/ mm2 in the arch soffit and in the pier atfoundation level respectively. These stresses are much lower thanthe allowable compressive strength of 40 N/mm2. This means thatfailure in the arch is not due to failure of masonry but due to functionof mechanism.

In addition to the above bridge, all the Arch bridges available over SW Railway have been analyzed in detail using the ring 1.5 software.The summery of the result is tabulated as below.

Division Total No. of arch No. of bridges No. of bridges for

bridges available analyzed which F S less than 1.5

Bangalore 148 148 01

Mysore 293 293 57

Hubli 167 135 8

Total 608 576 66

D) Finite Element AnalysisThe masonry arch bridge with a soil infill has been idealized ascomposed of two isotropic homogeneous materials, namely, masonryand filler. A two dimensional plane stress model of the bridge hasbeen used in this study. The finite element package ATENAencompasses many material model formulations for quasi-brittleconcrete like materials, such as a bi-axial failure surface with differenttension and compression thresholds, post crack strain softening basedon exponential and multi-linear softening, specific fracture energy ofthe material, compression softening in cracked concrete and otherfracture based parameters, such as crack interface shear transfer.

A two-dimensional plane stress finite element model for the masonryarch bridge is shown in Figure. The brick masonry has been assumedto have a modulus of 1800 MPa and a Poisson’s ratio of 0.2. The soilinfill has been idealized to have modulus of 800 MPa with a Poisson’sratio of 0.18. A relatively small tensile strength of 0.3 MPa has beenassumed for the masonry with a similar value of 0.3 MPa for the infill.These values are obtained through an iterative process of modelcalibration using the field measurements of the static load – deflectionand quasi-static moving load studies. The boundary condition on the

2.51

vertical face of the abutment (Kulem end) is restrained in thelongitudinal traffic direction and the base of the abutments and centralpier have been constrained in the vertical direction. The boundary atthe Castle Rock side abutment has been elastically constrained forlongitudinal movement using linear springs

Finite element model with boundary conditions

Loads on the finite element model

Contours of displacement in y-direction (in m) under self weight

2.52

Dis

plac

emen

t mm

LV

DT

2D

ispl

acem

ent m

m L

VD

T6

Contours of stress component σσσσσxx in Pa due to self-weight

Comparison of FEM predictions with measurements duringspeed test using formation 1. the formation moves from CastleRocck to Kulem at 30 kmph.

Based on the dynamic analysis, the first four natural frequencies arein the range of 5 - 11 Hz as observed from the field measurements.

2.53

E) Residual life of the BridgesThe stress based computation estimates the factor of safety to be1.5 for one million cycles. Here, each cycle corresponds to thepassage of one train (CC+8+2), assuming ten trains passing on thebridge per day.

Sl.No Br. No. Type of bridge Stress Based Remarks

Fatigue Life

(In years)

1 128 Arch bridge 66 Time required for

2 20 Arch bridge 86 an initial crack of

0.1 mm to develop

10 mm

323 139 A O W G Bridge 520

34 3 Plate Girder Bridge 411

45 102 Plate Girder Bridge 411

F) Results of InstrumentationThe preliminary analysis carried out based on the field data arematching with the theoretical values and codal provisions.

� Load factor is coming as almost 2.5 by instrumentation. So, allexisting arch bridges in good condition are fit for heavy haul of25 T or more axle load. This value is nearly equal to the valueobtained by arch ring 1.5 and modified MIXIE method

� Dispersion of longitudinal force in approaches is considerableand more than 25%.

� A static and slow moving axle load is more critical than fastmoving axle load. So over bridges in good condition, no speedrestriction should be normally imposed for carrying heavy axleload

� All bridges appears to be safe based on the study report exceptfor dynamic amplification factor which exceeds the codalprovisions.

2.54

ConclusionsIntroduction of higher axle loads in actual field started in the year2006. Since then a close watch has been kept on all the bridges, toobserve any abnormal behaviour of the structure and any symptomsof cracking, bending, bulging due to over stressing of the members.

With the experience so far has been:

(a) Behaviour of both sub structure and super structure of the bridgesis satisfactory under higher axle load trains (CC+8+2).

(b) No adverse effect or distress is noticed in the bearings and inthe superstructure. The isolated cases of bed block failures werereported in SKLR-SBHR section but these were not found to berelated to higher axle loads.

(c) All the arch bridges are being kept under close watch. So farnone of the Arch bridges have showed any signs of distress.

(d) There are 11 bridges where tractive effort had to be restricted to30T for WDG

4 MU operation. There bridges were provided boards

at their approach to caution the drivers and Locos are providedwith tractive effort limiting switch. The system has workedsatisfactorily and no adverse effect has been noticed on thesebridges. In the meantime, the strengthening works have alsobeen completed.

(e) Result of the instrumentation indicates that existing bridges aresafe under higher axle load train operation.

* * *

2.55

Strengthening of Bridges on Feeder Routes toEastern and Western Dedicated Freight Corridors

V. K. Govil*S.N. Singh**

Ashish Agarwal***

Synopsis : Certain routes on IR have been identified as feeder routesto Eastern and Western Dedicated Freight Corridors. These feederroutes are required to be strengthened as per loading prescribed forthat. IR has bridges built to various loading standards. Bridge Rulescame in 1892, while there are bridges constructed prior to that. It isnecessary to understand the comparison of various loadings toprecisely assess their effect on super-structures and sub-structures.This paper analyses the various issues involved and strengthening

required.

1.0 Introduction1.1 Various feeder routes identified to Eastern and WesternDedicated Freight Corridors are as below:-

1.1.1 Eastern Feeder Routes

S. Section Approx.No. Length

(kms.)

((i) Sonnagar-Garwa Road-Barkakana 311

(ii) Patratu –Gomoh including PD Branch Line 128

(iii) Sonnagar – Gaya – Gomoh 249

(iv) Gomoh-Pradhakhunta (39 kms.) including KusundaTetulmari (4.5 kms.), Katarasgarh – Nichitpur,Pradhankhunta – Pathardih links (24 kms.) 67.5

(v) Chandrapura – Dhanbad 36

(vi) Gomoh – Chandrapura in Gomoh – Chandrapura –Kokar – Muri – Chandil – Sini section 216.34

**EDCE/B&S, Railway Board**CBE, Western Railway***XEN/Design, Western Railway

2.56

(vii) Dhanbad – kartrasgarh – Jamuniatar – Chandrapura 35.6

(viii) Pradhankhunta-Asansol-Andal including coal branch lines 75

(ix) Andal-Sainthia 151

(x) Dankuni – Andul in Dankuni – Andul – Panskura –Haldia section 144.57

(xi) Dankuni – Dumduam Jn. – Ballugunj Jn. –Diamond Harbour – Baliganj Jn. – Budge Budge 101

(xii) Bhojidih – Mohuda - Gomoh 36

(xiii) Tatanagar - Chandil —

(xiv) Chandil – Bhojidih – Mohuda - Gomoh —

(xv) Andul – Panskura – Haldia in Dankuni – Andul –Panskura – Haldia section —

(xvi) Aligarh – Hardua ganj 15

(xvii) Kanpur - Paricha 219

(xviii) Mugalsarai – Unchahar via Janghai, Phaphamau 205

(xix) Varanasi – Sultanpur – Ulratia – Rosa 558

(xx) Zafrabad – Tanda 99

(xxi) Ludhiana – Beas – Govindwal Sahib 112

(xxii) Rajpura – Dhuri – Bhatinda (Lehra Mohabbat)_ 173

(xxiii) Hissar – Bhatinda – Suratgarh — Biradhwal 320

1.1.2 Western Feeder Routes

S. Section Approx.No. Lenght (kms.)

(i) Pipavav — Surendranagar – Viram — Mehsana 395

(ii) Kandla Port – Gandhidham – Samakhiali — Palanpur 312

(iii) Mundra Port – Gandhidham 66

(iv) Viramgram — Samakhiali 182

(v) Hazira – Surat 40

(vi) Ludhiana – Hisar – Rewari 348

(vii) Mumbai Port – Wadala – Kurla – connectivity with DFC 36

2.57

1.2 Approximately 4500 kms. of feeder routes is involved on eightzonal railways viz., CR, ER, ECR, NR, NWR, NCR, SER and WR.

2.0 Loading Standard for DFC Feeder Routes(i) Bridges being rebuilt of DFC feeder routes should have the sub-structure rebuilt on DFC loading (32.5t axle load) provided in IRSBridge Rules vide correction slip No.39. Super structure of thesebridges would be rebuilt to 25t loading – 2008 provided in IRS BridgeRules vide correction slip No.38.

(ii) Other bridges on DFC feeder routes requiring rehabilitation/strengthening should have required works carried out for 25t loading– 2008 provided in IRS Bridge Rules.

3.0 Comparison of 25t Loading -2008 with BGML, RBG andMBG Loadings

3.1 Comparison of EUDL for Bending moment (BM)Comparison of EUDL for bending moment alongwith CDA for 25tloading -2008 with BGML, RBG and MBG loadings for various spansis as below:-

Comparison Of EUDL For Bending Moment With CDA

S . Clear Effective B G M L R B G M B G 25t % % %span span LOADING- VARIA- VARIA VARIA(m) (m) 2008 T ION TION TION

OF 25t OF 25t OF 25t loading- loading- loading-

2008 2008 2008w. r . t . w . r . t . w . r . t .B G M L R G B M B G

1 1.83 2.21 91.6 91.6 100 100 +8.40 +8.40 0.00

2 3.05 3.45 104.8 102.1 104.8 107.83 +2.81 +5.30 +2.83

3 6.10 6.91 184.18 167.11 163.26 170.61 -7.95 +2.05 +4.31

4 9.15 10.00 221.83 189.93 185.30 184.80 -20.04 -2.78 -0.27

5 12.20 13.10 256.79 226.51 237.29 237.25 -8.24 +4.52 -0.02

6 18.30 19.40 315.64 275.38 286.49 300.63 -4.99 +8.40 +4.71

7 24.40 25.60 370.39 328.94 343.52 363.02 -2.03 +9.39 +5.37

8 30.50 31.90 422.33 379.54 397.78 423.26 +0.22 +10.33 +6.02

9 45.70 47.24 554.41 500.41 535.32 573.09 +3.26 +12.68 +6.59

2.58

Above comparison of EUDL for BM+ CDA indicates as below:-

(i) EUDL for BM+CDA for 25t loading-2008 is on higher side forsmaller span sizes such as 1.83m, 3.05m and 6.10m incomparison to BGML loading. Thereafter values for BM+CDAfor 25t loading is on lower side for span up to 24.4m incomparison to BGML loading and thereafter it increases againfor higher spans.

(ii) EUDL for BM+CDA for 25t loading-2008 is generally on higherside in comparison to RBG loading, except for 9.15m span.

(iii) EUDL for BM with CDA for 25t loading-2008 is almost withinvariation of 5% up to 18.3m span in comparison to MBG loading.It increases consistently beyond span 18.3m for 25t loading-2008 in comparison to MBG loading.

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3.2 Comparison of EUDL for Shear ForceComparison of EUDL for Shear Force with CDA

S . Clear O V E R B G M L R B G M B G 25t % % %span ALL LOADING- VARIA- VARIA VARIA(m) SPAN 2008 T ION TION TION

(M) OF 25t OF 25t OF 25t loading- loading- loading-

2008 2008 2008w. r . t . w . r . t . w . r . t .B G M L R G B M B G

1 1.83 2.58 90.6 90.32 91.5 94.5 +4.13 +4.42 +3.17

2 3.05 3.9 118.2 108.03 118.95 120.94 +2.27 +10.68 +1.65

3 6.10 7.09 173 152.09 164 166.17 -4.11 +8.48 +1.31

4 9.15 10.2 210.9 189.42 210.6 210.6 -0.14 +10.06 0.00

5 12.20 13.3 249.3 220.56 255.75 258.75 +3.65 +14.76 +1.16

6 18.30 19.65 329.3 294.03 327 329.25 0.00 +10.70 +0.68

7 24.40 26.05 406.5 365.18 408.75 432 +5.90 +15.47 +5.38

8 30.50 32.45 486 440.61 489.24 522 +6.90 +15.59 +6.28

EUDL for shear force with CDA for 25t loading-2008 is generally morethan that for BGML, RBG & MBG loadings.

3.3 Comparison of Longitudinal ForcesLongitudinal forces for 25t loading-2008 vis-à-vis BGML, RBG andMBG Loadings is as under:

Comparison of Longitudinal Force with Dispersion

S . Clear Loaded B G M L R B G M B G 25t % % %span Lenght LOADING- VARIA- VARIA VARIA(m) SPAN 2008 T ION TION TION

(M) OF 25t OF 25t OF 25t loading- loading- loading-

2008 2008 2008w. r . t . w . r . t . w . r . t .B G M L R G B M B G

1 1.83 2.58 1.89 0.00 0.70 5.00 +62.26 +100.00 +86.00

2 3.05 3.90 5.49 6.50 9.00 15.50 +64.58 +58.06 +41.94

3 6.10 7.09 16.84 6.50 17.30 17.32 +2.77 +62.47 +0.12

4 9.15 10.20 20.97 11.50 34.00 33.98 +38.29 +66.16 -0.06

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5 12.20 13.30 24.51 21.50 34.00 47.00 +47.86 +54.26 +27.66

6 18.30 19.65 29.65 34.00 56.25 56.22 +47.26 +39.52 -0.05

7 24.40 26.05 32.59 44.00 62.48 63.00 +48.27 +30.16 +0.83

8 30.50 32.45 38.60 52.50 75.00 74.97 +48.51 +29.97 -0.04

On comparison of longitudinal forces along with dispersion for 25tloading-2008 with BGML and MBG Loading the observations are asunder:

(i) Longitudinal force (LF) in bridges of MBG, RBG and BGMLloadings of span lesser then 6.1 m even after dispersion is morein 25t loading-2008. For span lesser than 6.1 m there is apossibility of substructure built in MBG, RBG and BGML loadinggetting failed due to 25 t loading-2008.

(ii) LF in bridges of MBG loading of span up to 30.5m is almostsame as for 25t loading- 2008 except for span 12.2m.Substructures built in MBG loading requires checking for 12.2m span and for span higher than 30.5 m.

(iii) F in bridges of BGML standard is lower than 25t loading-2008except it is almost same for 6.1m span. There is a higherpossibility of substructures except 6.1m span built up in BGMLloading getting failed in 25t loading-2008 and requires checking.

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(iv) LF in bridges of MBG loading of span up to 30.5m is almostsame as for 25t loading- 2008 except for span 12.2m.Substructures built in MBG loading requires checking for 12.2m span and for span higher than 30.5 m.

4.0 Issues Related to Checking of Existing Bridges to LoadingsStandard of Feeder Routes

4.1 Existing bridges are required to be checked for their suitabilityfor loading requirements of DFC feeder routes brought out in para2.0. While doing so, it has to be kept in view that on IR bridges areconforming to various loading standards, viz.

(a) Bridge rules came in 1892.

(b) Prior to 1892, bridges were built according to the Britain Boardof Trade Rules, which did not specify the longitudinal loads.

(c) Provision of longitudinal forces first appeared in bridge rulesin 1923.

(d) Detailed provisions on longitudinal forces were made in BridgeRules – 1926.

(e) BGML-1926 – prescribed train load of 7.67t/m with maximumTE of 47.6t for two loads.

(f) RBG – 1975 – prescribed train load of 7.67t/m with maximumTE of 75t for two loads.

(g) MBG – 1987 – prescribed train load of 8.25t/m with maximumTE of 100t for two loads.

4.2 Besides the issue of bridges built to various loading standards,it is also important to consider that on IR, there are two types ofsuper-structures, viz. standard spans to RDSO drawings and non-standard spans to zonal railway drawings. For standard spans, RDSOhas issued various drawings for steel and RCC/PSC super-structures.For non-standard spans and even in some cases for standard spans,drawings have been developed by railways. For sub-structure bridgedrawings, by and large, railways have their own designs/drawings.

4.3 Checking of non-standard super structures and all sub-structureshas to be done by the railways. However, suitability of RDSO’sstandard steel and RCC/RSC super structure drawings designed tovarious loading standards for 25t loading – 2008 have been checked

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and advised to zonal railways by RDSO and briefly the same is asbelow:-

4.3.1 RDSO standard steel super structure

(a) All steel standard spans are fit for 75 kmph speed, except 76.2mopen web girders to RBG loading, which is fit for 50 kmph.

(b) Bearings strengthening works required for bridges 24.4m spanand above.

4.3.2 RDSO standard RCC/PSC super structure

(a) RCC box to MBG loading are safe.

(b) RCC slabs of span 0.61m, 0.915m, 1.22m, 1.83m, 2.44m ofRBG and MBG loadings are fit for 75 kmph.

(c) Pre-tensioned PSC slabs for spans 3.05m. 3.66m, 4.57m, 6.10mand 9.15m of MBG loading are safe for 75 kmph.

4.4 Though it is apparent that many of standard steel and RCC/PSCsuper-structures are coming safe for 25t loading-2008 with restrictedspeeds after doing bearing works, sub-structure would be criticalprimarily from considerations of increase in longitudinal forces.Therefore, though major works in super-structures may not benecessary, except on condition basis etc., major works ofstrengthening of sub-structure would be required.

4.5 Arch bridges : These should be checked by Ring 1.5 and Ring2.0 provided physical conditions are satisfactory. Considerations bemade for adequate barrel length, drainage, cushion, physicalcondition, performance of repairs undertaken, etc.

5.0 RecommendationsWhile deciding strengthening works required, have considerationsfor following:-

� Design loading standard of the bridge.

� BGSL (BGML+BGBL) came in 1926 – Bridges constructed earlierrequire special scrutiny.

� Existing load running pattern on the routes – CC+8+2/CC+6+2and response of the bridges to same.

� Compare theoretical stresses under design load, load actuallyrunning and 25t loading – 2008.

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� CDAs given in Bridge Rules para 3.3.1 are for 125 kmph speed.

� As per clause 2.8.3.1 and 2.8.3.4 of Bridge Rules – dispersion oflongitudinal force not be taken for design of new bridges but upto25% of longitudinal force can be dispersed while checking existingbridges.

� Attention also invited to CS No.23 of IRS bridge sub-structure incode which reads as below:

“Whenever it is not possible to carry out theoretical checks, orwherever the results of theoretical checks are found to be inconsistentwith the physically sound condition of an existing bridge, running oflocomotives and rolling stock with heavier tractive force / brakingforce may be permitted subject to physical condition being certifiedand bridges being kept under close observation, as considerednecessary by the Chief Engineer. In such cases, the increase oftractive and/or braking forces shall not be more than 20% over bridgesabove the level of tractive and braking forces running over the bridgesfor the past one year or so.”

� For standard spans, suitability of super-structure for 25t loading-2008 issued by RDSO be referred.

� As longitudinal forces are more in 25t loading- 2008, suitabilityof sub-structure needs to be adequately evaluated from variousconsiderations brought out above.

* * *

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Formation Design and Specification for Heavy AxleLoad on Indian Railways

J. C. Parihar*J. S. Sondhi**

Rajesh Agarwal***

*Sr. Executive Director/Geo-technical Engineering/RDSO**Divisional Railway Manager/Lucknow/Northern Railway,***Director/Geo-technical Engineering/RDSO

Synopsis : Indian Railways have entered the era of heavy axle loadsby running of CC+6+2 & CC+8+2 loadings and have also startedconstruction of ‘Dedicated Freight Corridors’. Provision of blanketlayer on top of formation is essential to construct stable formation,suitable for running heavy axle loads. Design of formation layersincluding blanket has been be re-looked into for catering heavy axleload train operation.

The present paper discusses & suggests the specifications &thickness of blanket layer For IR, suitable for heavy axle load trainoperations for different axle loads with incorporation of new featureslike, two layered concept of blanket layer & layer of prepared sub-grade, which also covers additional Filter Criteria & Los AnglesAbrasion Value for blanket material. Similar to highways & someother railway systems, CBR value of soil & blanket material havebeen recommended for material selection & formation design.

1.0 IntroductionOver the years, increase in traffic and speeds have placed a greaterstructural demand on conventional track, constructed initially to caterfor much lighter traffic. Gradual improvement to track support systemhowever, remained confined to track superstructure, i.e. rails, sleepers,fastening etc. The sub-structure below sleeper level remainedpractically unchanged.

Provision of blanket on top of formation has become a necessity.Due to non-provision of blanket, large stretches of track on IndianRailways are having speed restrictions, uneconomical maintenancepractices as well as have become an impediment in the introductionof higher speed and higher axle loads viz. CC+8+2 loading & 25 T.

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Traditionally, blanket layer of single specified material, as thick as 1meter or more, was recommended, which becomes very costly &difficult to provide. Under the circumstances, multi-layered systemof formation layers for use in top portion of formation has been evolved& recommended from strength as well as economic considerations.

2.0 Historical Developments on Blanket Layer2.1 Provision of blanket layer on Indian Railways was stipulated inAugust-1978 for the first time in the ‘Guidelines for Earthwork inEmbankments & Cuttings of New Construction, Doubling &Conversion Projects’, for a thickness about 30cm in ordinary clayeysoil & 60cm, if formation soil is weak. Subsequently, in “Guidelinesfor Earthwork in Railway Projects” May 1987, one metre thick blanketlayer was recommended for all new constructions, keeping the futuregrowth of traffic densities and axle loads as well as the experiencewith already existing troublesome formations.

2.2 Later, Railway Board, vide their letter no. 90/CEII/SF/9, dated12.4.1991, and modified provisions of “Guidelines for Earthwork–1987to provide blanket (not be less than 30cm) duly taking into accountthe type of soil, rainfall and density of traffic and other factors relevantto the site conditions. It further stipulated that Sub-ballast of 15cmdepth below the ballast layer, comprising of locally available coarsematerial so as to serve as an effective medium between the formationearth and ballast stone may be provided, if decided by Chief Engineer(Const.) in-charge of the project”. The instructions regarding thicknessof blanket were again modified in terms of Railway Board’s letter no.94/CE-II/MB/2, dated 10.12.98 recommending blanket thicknessbased on axle load, GMT & speed.

2.3 In August 2001, committee of four SAG officers recommendedprovision of blanket thickness based on various soil types, whichhas subsequently been adopted in RDSO’s revised ‘Guidelines ForEarthwork in Railway Projects : July 2003’.

3.0 Functions of Blanket Layer3.1 Blanket is a layer of coarse grained material between ballastand sub-grade, spread over entire width. On some other railwaysystems of the world, this layer is also called as sub-ballast. Provisionof blanket layer helps in :

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1. Improving the bearing capacity by modifying the stiffness andachieving a better distribution of transmitted loads on the sub-grade soil, thus preventing ballast penetration into the formation.

2. Reduction of induced stresses on the top of sub-grade to atolerable level.

3. To prevent mud pumping and fouling of ballast by upwardmigration of fine particles from the sub-grade.

4. To prevent damage of sub-grade by ballast.

5. Shedding surface water from the ballast and help drain it awayfrom the sub-grade.

6. Protection of sub-grade against erosion and climatic variations.

Thus, blanket layer serves Stress Reduction Function as a PrimaryFunction and Separation Function, Drainage Function & Preventionof Mud Pumping, as Secondary Functions. These functions are fulfilledeffectively, if specifications of blanket material are such that : i) Thematerial is coarse grained, hard and well-graded and ii) Maximumpercentage of fines (particle size less than 75 microns) present inblanket material is limited to 10% to 12%. Allowing more fines inblanket material leads to plastic behaviour of blanket material but aminimum percentage of fines are required to give binding property tothe blanket material.

4.0 World Railway Practices –Blanketting Benchmarking

4.1 European Railways (UIC) : As per UIC code 719 R, 2008,minimum thickness (e) of track bed layers is given by the formula; e= E + a + b + c + d + f as per figure 1.

Fig. 1. Components of Formation in UIC

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where,

e = Total depth of ballast & blanket

E = Factor depending upon quality class of soil used inprepared subgrade

a = Factor depending on UIC groups based on GMT

b = Factor depending on type & length of sleeper

c = Factor depending on different working conditions onexisting lines

d = Factor depending on axle load of hauled vehicle

f = Factor depending on inclusion of geo-textile based onquality class of prepared sub-grade.

The values of above factors, as given in the UIC-719R, 2008 code areas under:

E = 0.70 m For QS1 soils used as prepared sub-grade

E = 0.55 m For QS2 soils used as prepared sub-grade

E = 0.45 m For QS3 soils used as prepared sub-grade

(Thickness of prepared sub-grade varies from 35 cm to 50 cm)

a = 0 For UIC groups 1-4

a = -0.10m For UIC groups 5 & 6

b = 0 For wooden sleepers of length 2.60m

b = (2.50-L) / 2 For concrete sleepers of length L (b in m, L inm, if L > 2.50m)

c = 0 For usual dimensions

c = -0.05 m For difficult working conditions on existing lines

d = 0 For 200 kN axle load

d = 0.05 m For 225 kN axle load

d = 0.12 m For 250 kN axle load

f = + Track bed must include a geo-textile for soil of QS1 or QS2

class

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Soil Quality Classes QS0, QS1, QS2 & QS3 are defined in UIC Codeare as under :

Soil Type (Geo-technical Classification) Soil QualityClass

Organic soilsSoft soils containing more than 15% fines (1) with QS0

high moisture content: therefore unsuitable forcompaction.Thixotropic soils (2) (e.g. quick clay)Soils containing soluble material (e.g. rock salt orgypsum)Contaminated ground (e.g. industrialwaste) Mixed material/organic soils (2)

Soft soils containing more than 40% of fines (1) QS1

(except for soils classified under 0.2)Rocks whichare very susceptible to weathering, e.g. Chalk withρd<1.7t/m3 and high friability and Marl, Weatheringshale

Soils containing 15% to 40% of fines (1) (except QS1 (3)

soils classified under 0.2)Rocks which aremoderately susceptible to weathering, e.g.Chalk with ρd <1.7t/m3 and low friability andUn-weathered shale Soft rock e.g. Microdevalwet with (MDE)>40 and Los Angles (LA) > 40

Soils containing from 5% to 15% of fines (1) QS2 (4)

Uniform soil containing less than 5% of fines (1)(Cu d” 6)Moderate hard rock, e.g. : If 25<MDEd”40and 30<LAd”40

Well graded soils containing less than QS3

5% of fines (1) And Hard rock, e.g. : If MDE d”25and LA d” 30

(1) Certain Railways sometimes include these soils in quality classQS1.

(2) These soils can come under quality class QS2, if the hydro-

geological and hydrological conditions are good.

(3) These soils can come under quality class QS3, if the hydro-geological and hydrological conditions are good.

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4.1.1 Specifications of Blanket Material in UICi) Blanket material must be a well graded sandy-gravel material

i.e. (Cu>6 and Cc between 1 & 3).

ii) It should be sufficiently durable e.g. Los Angeles value lessthan 20 or 25.

iii) Some railways require sandy gravel to contain at least 30% ofcrushed stone.

iv) It should satisfy Terzaghi Filter criteria with sub-grade soil.

v) If blanket layer is in contact with fine grained (silty or clayey)sub-grade, it should have about 20% fine sand (particle sizeless than 0.2 mm).

4.2 Practices of American Railways : American RailwayEngineering and Maintenance-of-way Association (AREMA) Manualof Railway Engineering 2002 recommends use of 12 inches ballastand 12 inches sub-ballast on main track. Use of soils with PlasticityIndex > 12 for a depth within 4 feet below sub-ballast should beavoided, if possible.

4.2.1 AREMA Specifications for Sub-ballast :i) Material to be used is similar to highway bases and sub-bases

such as crushed stone, natural or crushed gravel, natural ormanufactured sands, crushed slag etc.

ii) Sub-ballast shall be granular material so graded as to preventpenetration into sub-grade and penetration of ballast into sub-ballast zone.

iii) Filter principles should be used in drainage to the grading ofsub-grade.

iv) Maximum size of sub-ballast should not exceed maximum sizeof ballast.

v) Not more than 5% of the sub-ballast should pass the no. 200sieve (60 micron).

4.2.2 Filter Criteria Requirement :The two separation gradation for drainage filter criteria are :i) D15 (filter blanket) < 5 x D85 (sub-grade)

ii) D50 (filter blanket) < 25 x D50 (sub-grade) (Ratio of D50 in range of9 to 30)

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Criteria ensures blocking the upward movement of particles atthe coarsest end of protected soil (D85).

iii) Additional criteria to ensure adequate permeability to drain sub-grade -

D15 (filter) < 20 x D15 (sub-grade) (Ratio of D15 in range of 6 to 18)

4.3 Blanket/Capping Layer In Australian Railways : AustralianRailway Track Corporation provides 15 cm blanket/capping materialover 0.5 m of sub-grade having CBR values more than 8 or over 1 mof sub-grade if its CBR is in range of 3 to 8 as shown in Figure 2below :

Fig.2 Formation Details in Australian Railways

4.3.1 General Requirements of Blanket Material in AustralianRailway : Material proposed for capping shall be a well gradednatural or artificially blended gravel/soil. It shall have sufficient finesto permit it to be compacted to high densities by static or vibratorysteel-tyred rollers or by ballasted pneumatic-tyred rollers. Materialssuch as natural ridge gravel, free from vegetable matter, rippedsandstones with low clay content and crushed and blended toughdurable rock or slag, have been found to meet material properties ofthis specification. Natural gravels may be combined to providematerial which conforms to this specification. Crushed rock shallinclude such added material as necessary for the combined materialto satisfy the requirements of this specification.

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4.3.2 Particle Size Distribution : Material shall be well gradedwith typical particle size distribution as follows :

Table 1

AS Sieve Percentage Passing Nominal Size (20mm)

53 mm 100

37.5 mm 100

26.5 mm 100

19.0 mm 95-100

9.5 mm -

4.75 mm -

2.36 mm 30-80

0.075 mm 6-10

4.3.3 Atterberg Limits :

� Liquid Limit : Maximum 30 (35 for arid areas)

� Plastic Limit : Maximum 20

� Plasticity Index : 2 -10 (2 -15 for arid areas)

� Linear Shrinkage : Maximum 3%

4.3.4 Maximum Dry Density : Minimum .2.0 t/cum

4.3.5 Soaked CBR : Min. 50%, determined on material compacted to 95% of MDD.

4.3.6 Granular Layer Thickness based on ORE D117 Report and on Various Railways

The relation between granular layer thickness versus sub-grademodulus according to ORE D117 for various Railways is reflectedin the adjoining Figure.

(Ev2) or CBR values or soil types are correlated to the granularlayer thickness required.

As can be seen, the required thickness

e= (ballast + sub-ballast), for given sub-grade properties, differson various Railways.

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Fig. 3 Ballast + Sub-ballast thickness versus sub-grade CBR/Modulus (based: ORE D117, Design Handbook RP28)

5.0 World Railway Practices –Earthwork BenchmarkingVarious design methods of formation, particularly for blanketthickness, are in use in different railway systems. These are basedon different properties of soil used in embankment construction whichgovern the behaviour of soil viz. percentage of fines (size less than75 microns) present in the soil, CBR value of soil, undrained shearstrength Cu of soil etc. These methods have been described brieflyas under :

5.1 UIC method (Based upon fines in soil) : Basis of the designis mainly governed by the percentage of fines present in the subgradesoil. The different soils have been grouped in three soil groups viz.QS1, QS2 & QS3 based mainly on percentage of fines in the soil.The blanket thickness for a soil of a particular group has beendetermined for different axle load, speed, GMT and other parameters.This method has already been described briefly in para 6.1 which isbased on UIC Code 719 R, 1994 and ORE report No. D - 117 RP 28.

5.2 British Railway Method (Based on Threshold Stress of soil)This method developed by British Railways in 1970s, deals withselecting the granular layer thickness based on threshold strengthof the subgrade soil. The objective is to limit the stress on the subgradesoils to less than a threshold stress in order to protect againstsubgrade failure by excessive plastic deformation, more pertinent incase of cohesive soils.

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The threshold stress is determined from repeated load tests in whichthe cumulative strain of the soil layer is noted as a function of thenumber of loading cycles applied. For such (clay) subgrade soils,there exist a value of the stress below which soil will experienceterminating deformation but if subjected to the stress value higherthan that, the soil show non-terminating deformation ( i.e. the rate ofcumulative plastic deformation is extremely rapid) and ultimately failsin shear. Such limiting value of the stress has been termed asthreshold stress. Such soils subjected to repetitive triaxial tests inlaboratory would fail before certain nos. of cycle ( typically 3000)application of test loads causing stress above the threshold stresslevels.

Design procedure involves determination of stress at top of subgradedue to design axle load including dynamic augment. Threshold stressis determined by conducting cyclic triaxial tests on soils. Blanketthickness is determined such that stress at top of subgrade due tomoving axle load is less than threshold strength of the subgrade. Inabsence of cyclic triaxial tests, threshold strength of subgrade canbe approximated as 45% of Unconfined compressive strength of(clayey) subgrade.

Design curves for the subgrade giving the depth of granular layer(ballast & blanket) have been developed for different axle loads andthreshold strength of soil, and given in ORE Report No. D-71 RP 12.

5.3 Association of American Railroads (AAR) Method ( by Liand Selig ) : The AAR method is based on the Li & Selig (1998)design approach developed for design of sub-grade, and adopted onAmerican Railways System. Li & Selig (1998) based on detailedexperimental observations, presented a rational design method andconsidered two failure criteria:

(i) Progressive shear failure

(ii) Excessive plastic deformation

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Fig 4 . Sub-grade progressive shear failure

Fig. 5 : Excessive Sub grade Plastic Deformation (Ballast Pocket)

Design Criteria: The two criteria used to design the granular layer(ballast + sub-ballast) thickness on top of formation, for preventingsubgrade failures, are based on: (i) limiting cumulative plastic strainat the subgrade surface, intended to prevent subgrade progressiveshear failure, and (ii) criterion to prevent excessive sub grade plasticdeformation.

Both criteria need to be evaluated to determine the one that gives thelarger granular layer thickness in each case.

Design Procedure 1 - This design procedure is used for determininggranular layer thickness based on criterion of limiting cumulative plasticstrain at the subgrade surface. The design procedure consists of thefollowing 3 steps:

1. Prepare the information required for the design, including:

Traffic conditions: Dynamic wheel load must be determined usingeq. (i) or based on actual measurements, and the number of loadrepetitions for the design period must be determined using eq. (ii)

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(i) (Pdi )= (1+ 0.0052V/D) Psi

(ii) Ni = T / (8 Psi )

Where,

Pdi - dynamic wheel load in kN,

Psi - static wheel load in kN,

V – speed in kmph

D – Wheel Diameter in meter,

Ni – Number of load repetitions in the design period

T – Total traffic tonnage for the design period

εpa - allowable cumulative plastic strain at sub grade top

Allowable strain:1. The magnitude of the allowable cumulative plastic strain at thesub grade surface εpa must be determined for a certain number ofload repetitions (i.e. for the design period)Sub grade characteristics: The sub grade soil type, soil compressivestrength σs and the soil resilient modulus Es must be determined.Granular material: The resilient modulus Es for the granular materialmust be specified.

2. Determine the allowable deviator stress at the sub grade surface.This can be done using the charts in Appendix A of AAR Report No.R-898. This is completely based on the information obtained fromstep 1, i.e. soil type, the allowable cumulative plastic strain at thesub grade surface for the design period, and the soil compressivestrength. However as an alternative to the allowable strain determinedfrom the first step, the allowable deviator stress at the sub gradesurface may be selected directly at this step.

3. Select the required granular thickness to prevent the sub gradeprogressive shear failure as follows:

� Calculate the strain influence factor Ie by the equation, Ie= σda A/Pdi

Where σda = allowable deviator stress at the sub grade surfacedetermined from step 2; Pdi = design dynamic wheel load

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determined from step 1; and A = area factor used to make thestrain influence factor dimensionless. The area factor A is 0.645m2 (1000 in2).

� Determine the value of H/L (H – Granular Layer Thickness & L –Length Factor) corresponding to the strain influence factor Ie

using a design chart A2 in Appendix A of AAR Report No. R-898(Li & Selig October 1996), for the values of granular layer resilientmodulus Eb and the sub grade resilient modulus Es.

� Multiply H/L by the length factor L to get the required granularlayer thickness H. Length factor is used to make the designcharts dimensionless. The L is equal to 0.152m (6 in).

Design Procedure 2 : This procedure is based on the criterion whichlimits total plastic deformation of the subgrade layer. The granularthickness design consists of the following 3 steps:

1. In addition to the information required in design procedure 1,design procedure requires knowledge of the thickness of thedeformable sub grade layer T. The allowable cumulative plastic strainat the sub grade surface for design procedure 1 is replaced by theallowable total plastic deformation of the sub grade layer for designprocedure 2.

2. Calculate the deformation influence factor Ip by the following

equation (Li and Selig 1998):

ρa /L

Ip = ——————— x 100

a (Pd /σs A)m Nb

Where:

ρa

= allowable total sub grade plastic deformation for thedesign period

N = total equivalent number of load repetitions during thedesign period

Pdi = design dynamic wheel load

σs = soil compressive strength

a, b, m = material (soil) parameters

and A, L = area and length factors.

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3. Select the required granular layer thickness to prevent excessivesub grade plastic deformation as follows:

� Select the design chart as given in Appendix B that the bestcorresponds to the existing soil type, sub grade resilient modulus,and granular layer resilient modulus.

� Calculate T/L (where T is thickness of deformable subgrade layerfrom bottom of granular layer to top of rigid layer) and locate thepoint in design chart as given in Appendix B corresponding to Ipand T/L. Obtain the value of H/L for that point, and multiply H/Lby the length factor L to get granular layer thickness H.

6.0 Design Of Formation For 25, 30 & 32.5 T Axle Load On TheBasis Of Different Methods : Calculations of blanket thicknessrequirement have been done based on above methods for 25T, 30T& 32.5T axle loads. These are as under :

6.1 UIC Method (Based on fines in Soil) :Recommendations havebeen made in UIC Code 719 for axle loads in range of 20 to 25 tonne.Since formation design is to be done for 30 T & 32.5 T axle loads,extrapolation has been done for 30 tonne and 32.5 tonne axle loadsfrom UIC provisions. Keeping in view the other relevant factors, Speed,GMT, Sleeper Length suitable for Indian Railways, detail calculationsof blanket thickness for various soils, based on UIC practices havebeen carried out.

Calculated Thickness of blanket material & prepared sub-grade andtype of sub-grade alongwith soil types as per IS Classificationbelonging to various ‘Soil Category SQ’ have been given in Table-2.Soil Categories SQ1, SQ1 & SQ3 have been modified slightly fromUIC practices to suit Indian conditions & BIS Classification system.

1. Thickness of blanket material has been worked out with theprovision of 300mm ballast.

2. Recommended blanket thickness is suitable for GMT >=25 &Speed < 160 kmph.

3. Geo-textile should be provided below blanket layer, if preparedsubgrade is of SQ2 soil.

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Table 2 - UIC Based Two Layers System of Blanketing OnTrack Formation

(Ref : Calculations based on UIC practices in terms of UIC Code719R-1994)

Soil Quality Top Soil of Formation Recommended Thickness (mm)Category in (prepared Subgrade) of Blanket for Axle Loads

Sub-grade Quality Thickness 25 T 30T 32.5 T(mm)

SQ1 SQ2 500 250 450 600SQ1 SQ3 500 150 350 500SQ2 SQ2 - 250 450 600SQ2 SQ3 350 150 350 500SQ3 SQ3 - 150 350 500

Soil Quality Class SQ1, SQ2 & SQ3 has been given in Table 3 below.

Table 3 - Description of Soil Quality Class

Soil Description w.r.t. Fine- Soils as per IS ClassificationQuality Particles (size less than Conforming to Referred

75 micron) Soil Quality

SQ1 Soils containing fines > 50 % CL, ML, CL-ML, CI, MI, CH, MH

SQ2 Soils containing fines from GM, GC, SM, SC12% to 50%

SQ3 Soils containing fines < 12% GW, GP, SW, SP, GW-GM,GW-GC,SW-SM, GP-GM,GP-GC, SP-SM, SP-SC

6.2 AAR Design (Selig Method) – Based on Cumulative Strain& Plastic Deformation CriteriaBased on AAR method, as described in para 6.3 above,calculations have been done for 25, 30 & 32.5 T for differentvalues of Compressive Strength, σs of soils. The results of

calculated blanket thickness are given in Table 4 below.

Table 4 - Calculation of Blanket Thickness (in cm) Fordifferent Axle loads & CBR of soil

CBR Subgrade Axle Load 25 T Axle Load 30 T Axle Load 32.5 T(%) Compr(Indic essive From From Maxi- From From Maxi- From From Maxi--ative Strength Cumulat- Cumulat- mum of Cumulat- Cumulat- mum of Cumulat- Cumulat- mum ofvalue) σs ive Strain ive Defor two ive Strain ive Defor two ive Strain ive Defor two

(kPa) Criterion mation Criterion Criterion mation Criterion Criterion mation CriterionCriterion Criterion Criterion

2 60 120 120 120 - - - - - -

3 90 70 85 85 120 120 120 - - -

4 120 30 25 30 55 50 55 75 75 75

5 150 15 Nil 15 25 15 25 35 40 40

6 180 Nil Nil Nil 15 Nil 15 20 Nil 20

Note :1. Value of T (here T is assumed as 2m), the depth of deformable

layer is site specific. Hence, actual design may vary from site tosite.

2. AAR method is based on the approach that stress on subgradeis less than permissible strength such that plastic cumulativedeformation does not take place over the design period.

3. Calculations for granular layer thickness have been done usingsoil parameter & chart of CH type of soil assuming worst soilconditions.

The design calculations have been done with following assumptionsof typical values or empirical relations :

� Soil Compressive Strength, (in kPa) , σs = 30 x CBR

� Elastic Modulus of ballast, Eb has been assumed to be 140MPa.

� Elastic Modulus of Soil, Es =10 x CBR (For CBR <= 5) &Es = 17.6xCBR 0.64 (For CBR> 5) (Ref : Page no 53 of IRCGuidelines for the Earth design of flexible pavements, IRC:37-2001)

� Values of a, b & m for soil & Curves for Soil have used for CHtype soil..

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� Depth of deformable subgrade,T has been assumed as 2.0 m.

� GMT is 30 and design period is 5 year. ( i.e. Total Design GMTis 150)

� Permissible cumulative plastic strain, εpa at the end of designperiod is 2%.

� Permissible cumulative plastic deformation at the end of designperiod is 25 mm.

� Ballast Thickness is 30 cm.

7.0 Multi-layers System of Formation Design7.1 From the observations of provisions of various World RailwaySystems, it is evident that there is requirement & practice of notallowing poor soils in top one metre thickness of sub-grade andstrengthening of about top 1 metre of formation is necessary withmaterial of superior quality like blanket material. From the perusal ofpractices adopted in other leading railway systems, it is evident thatmulti-layer formation system – layers with adequate strength andstiffness to be adopted. Layers comprise of blanket layer, preparedsubgrade/top layer of formation etc. is preferred in place of singlelayer blanket system. The specifications and thickness of variousformation layers specified are in line with practices of UIC, AAR andother World Railways.

7.2 As on date, one metre blanket layer is being provided for 20.32Taxle load train operation on Indian Railways with single type of materialhaving superior specifications, which many a times is available atvery high cost; thus it proves to be uneconomical. Also, dispensationto its provisions is normally granted by Railway Board on the requestsof Zonal Railways.

7.3 It has also been observed that AREMA recommends for not usingsoil having plasticity index more than 12 in top 4 feet thickness ofsub-grade; UIC provides layer of prepared sub-grade of 35 cm to 50cm of better material and Australian Railways provide 50 cm to 1metre of sub-grade having CBR value more than 8.

7.4 Similar to AAR, UIC or Australian Railways, total requirement ofblanket layer can be provided with two types of materials, upperlayer which is in contact with ballast can be of superior quality andlower layer which is in contact with sub-grade can be with

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specifications such that poor material should not appear in top portionof sub-grade.

7.5 Proposed thickness of blanket material & prepared sub-gradeand types of sub-grade alongwith soil types as per IS Classificationbelonging to various ‘Soil Category SQ’ have been given in Table-2 &also shown in Fig.-3. Soil Quality Categories SQ1, SQ2 & SQ3 havebeen modified slightly to suit Indian conditions & BIS Classificationsystem.

7.6 Prepared sub-grade should be preferable with SQ3 soils, having

fines less than 12%. If prepared sub-grade is of SQ1 or SQ2 typesoils, geo-textile layer shall be provided at junction of bottom of blanketlayer & top of prepared sub-grade. It has been observed that formationconsisting of soils having sufficient fines and having plasticity indexmore than 15 poses formation problems. Therefore, if SQ1 or SQ2

soils are used as prepared sub-grade, its Plasticity Index should notbe more than 15.

7.7 From the stress analysis, it is evident that most of stresses forheavy axle load up to 32.5 T load are dissipated upto 1.5 m depthbelow bottom of ballast, thereafter the stresses are within tolerablelimit of stresses including reasonable factor of safety for soils. Themajor stress region occurs upto depth of 1 to 1.5m below bottom ofballast. This region is to be provided with blanket layer which or inlower layers supplemented / replaced by prepared subgradeparticularly in bottom portion. Also, below the blanket layer, the layerof prepared/ good imported soil with minimum prescribed CBR valueis essential and has been recommended as prepared subgrade layerupto depth of about 1.5m below top of formation.

8.0 Formation Design Based on CBR Concept8.1 From the ages, Highways system are using the CBR (CaliforniaBearing Ratio) as the basis for design of subgrade and GranularSub-base (GSB – similar to blanket material in railways) and thissystem is still prevalent now. California Bearing Ratio (CBR) test is apenetration test developed by the California State Highway Departmentof USA for the evaluation of subgrade strengths for roads andpavements. California Bearing Ratio (CBR) is defined as the Ratio ofForce per unit Area required to penetrate a soil mass with a circularplunger of 50 mm diameter at the rate of 1.25 mm/minute to thatrequired for corresponding penetration of a standard material. From

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the perusal of UIC and Australian railways system of formation design,it is evident that they are also using the CBR value as the basis ofselection of material viz. soil, blanket material and basis for designthe thickness of various layers.8.2 Indian Railways is also considered to adopt the CBR value asthe criteria for selection of formation materials and design of formationsince CBR value of soil gives direct indication of strength of soil andits behavior as a embankment material. This test is well establishedand easy to determine in the laboratory as per procedure laid downin BIS Code– IS : 2720 (part 16) – 1979. From the literature andexperience, it has been established that Clayey soils with highplasticity i.e. CH & MH type have the CBR value less than 3 whichshould be avoided to be used in embankment. Prepared subgradematerial which is to be used in top layer of formation should haveCBR value more than 8 so that blanket thickness requirement isreduced substantially. Blanket material should have sufficient CBRvalue to avoid penetration of ballast particles into blanket layer. Thus,on Indian Railways, CBR value of soil which is used as embankmentfill is recommended as minimum 3 and CBR value of preparedsubgrade as a material for top layer of formation as a minimum 6-8and for blanket material is decided as minimum 25.8.3 Considering the relevant good features of Indian Highway system(Ref; Indian Road Congress Code, IRC:37 on ‘Guidelines & Designof Flexible Pavements) and foreign railway practices, strength baseddesign system has been evolved. Minimum CBR value of subgrade/prepared subgrade have been prescribed for selection of soil/materialfor the subgrade.

9.0 Revised Specifications of Blanket :9.1 Specifications of the material for blanket layer over prepared sub-grade should be such that it is well-graded sandy gravel layer ofadequate hardness. Particles size gradation curve should be moreor less within Enveloping Curves of blanket material as shown in Fig.6 below & Grading Percentages within the range given in Table 5.below and should also have following criteria satisfied :

i) Cu > 7 and Cc between 1 and 3.

ii) Fines (passing 75 microns) : 3% to 10%.

iii) Los Angeles Abrasion value < 35%.

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iv) Minimum required Soaked CBR value 25 of the blanket materialcompacted at 100% of MDD

In exceptional cases on technical and economic considerations, LAAvalue may be relaxed upto 35 % by PCE on Open Line & CAO/C inconstruction projects.

v) Filter Criteria should be satisfied with prepared subgrade/subgrade layer just below blanket layer, as given below :

Criteria–1: D15 (blanket) < 5 x D85 (sub-grade)

Criteria–2: D15(blanket) > 4 to5 D15 (sub-grade)

Criteria–3: D50(blanket) < 25 x D50 (sub-grade)

Filter Criteria is optional, at present. This can be adopted with theexperienced gained of its compliance for different types of soils withblanket.

Table 5. : Grading Percentage of Blanket Material

SL IS Sieve Size Percent Passing (by weight)

1. 40 mm 100

2. 20 mm 80 - 100

3. 10 mm 63 - 85

4. 4.75 mm 42 - 68

5. 2 mm 27 - 52

6. 600 micron 13 - 35

7. 425 micron 10 - 32

8. 212 micron 6 - 22

9. 75 micron 3 - 10

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Fig. 6 : Enveloping Curves for Blanket Material

10.0 Qualifying And Quality Assurance Tests (Mandatory) :

Qualifying tests as part of pre-selection of good earth for tracksubgrade, embankment fill is required to be carried out.

Also, quality of compaction is required to be done to ensure goodquality construction.

i) Selection of soil: For selection of soil to be used asembankment fill CBR test is required to be conducted on material.CBR test is conducted on ground soil, embankment fill, preparedsub-grade & blanket material to ensure the minimum specifiedCBR value of these materials to be used in construction. Thistest is carried out on soil sample in laboratory as per proceduregiven in IS:2720 (Part 16)-1987 & in field as per IS:2720 (Part31)– 1969.

ii) Quality Assurance Test on Compacted Layer : QualityAssurance Tests are required to be conducted on part completionstages of formation, prior to clearing for further earthwork, tracklinking work:

Heavy Proctor test is required to be conducted to determine theMaximum Dry Density of soil as per IS: 2720 (part 8). In-situ densityis measured in the field by Sand Replacement Method (IS: 2720 –part 28) or Core Cutter Method (IS: 2720 – part 29) to calculate thedegree of compaction. This shall be determined in laboratory as perBIS procedure with the specified frequency of earthwork quantity, asenvisaged in ‘Guidelines of Earthwork in Railway Projects, GE:G-1,July 2003.

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Second Step Plate Load Test (Optional) is required to beconducted in-situ for measurement of Deformation Modulus EV2 ofcompacted layers of embankment, blanket, prepared subgrade etc.The test procedure has been detailed in German Code DIN:18134-2001,’Determining Deformation & Strength Characteristics Of SoilBy Plate Loading Test”. The minimum value of EV2 should be ensuredat different levels as specified.

10.1 Frequency of Quality Assurance Tests :a) CBR test for selection of formation materials and other tests

required for ensuring conformation of the materials (blanket,crusher run) as per specification e.g. size gradation, Cu, Cc,Los Angles Tests, OMC/MDD etc. shall be conducted at followingfrequency :

i) Embankment Fill : one set of tests for every 5000 cumii) Prepared subgrade : one set of tests for every 2000 cum

iii) Blanket material : one set of tests for every 500 cum

b) In-situ Degree of Compaction (or In-situ dry densitymeasurement) test shall be conducted on each compactedlayers in random pattern at following frequency for the differentlayers :

o Embankment Fill : one density measurement at every500 sqm surface area of each of the compacted layers

o Blanket layer & Prepared Subgrade : one densitymeasurement at every 200 sqm surface area of eachof the compacted layers.

c) Second step Plate Load Test is optional quality assurance teston compacted surface. This should be done for EV2 measurementat top of each formation layers eg. at sub-soil, compactedsubgrade, prepared subgrade, crusher run, blanket etc. at thefrequency of one test per km length of section.

11.0 Ground Improvement Methods :

11.1 Field tests are required to be conducted on sub-soil strata, suchas Plate load test for determination of Elastic Modulus at secondloading (EV2), Standard Penetration test to determine N-value, andUnconfined Compression Test or Vane Shear Test to determineunconfined compressive strength or undrained cohesion, Cu. If values

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of these test parameters, as specified in following para are not achievedthen ground improvement is required.

11.2 For ground soil/ sub-strata layers with low bearing capacities,assessed by following evaluation parameters:

(i) Ev2 value less than 20 MPa, (Optional) or

(ii) undrained cohesion (Cu) < 25 kPa, or

(iii) N-value (determined from Standard Penetration Test – SPT< 5, shall require Ground Improvement.

Strengthening of sub-strata soil layers can be carried outusing one or more of the following techniques, like:

- removal and replacement ( R&R) of weak soil,- stage constructions of the fill, preloading and surcharging,- Installation sub drainage system,- In-situ pile, Sand Gravel Compaction pile, Stone Columns

- Vibro-floatation,

- lime pile, Injection/ lime slurry pressure injection/ion exchange,

- Stir & Mixing, Sand mat, Geosynthetics etc.

12. Formation Specifications for Heavy Axle Load :

12.1The following Specifications for two different systems for blanketsubgrade, embankment fill are mandatory provisions to be adopted,as follows:

i) Conventional blanket layer over formation subgrade

ii) Blanket layer over prepared subgrade layer (good/importedsoil)

Any of the two system may be considered for adoption in the fieldbased on good soil availability and material cost economics. Thedetailed technical specifications for design of formation for heavyaxle loads has already been circulated vide RDSO report no. RDSO/2007/GE: 0014 in Nov 2009 as approved by Railway Board vide letterno. 2007/CE-I/Geotech/02 dated 26.10.2009.

12.2 In order to design & construction of stable formation for heavyaxle load, EV2 should be determined in the field as per proceduregiven in German Code DIN : 18134 at ground. Undrained shear

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strength, Cu of ground soil from Unconfined Compression (UCC) testor Vane Shear Test and Penetration Number (N – Value) from StandardPenetration Test should also be determined. If EV2 value is lessthan 20 MPa or Sub-soil strata having (Cu) < 25 KPa (mostly inMarshy area) or N-value < 5 will also require ground improvement.

12.3 If, naturally available materials do not meet the desiredspecifications, blanket material can be produced by mechanicalprocess from crushing or blending method or combination of thesetwo methods. Naturally available sand, quarry dust or crusher run, ifavailable at low cost, can be used as prepared subgrade also.

13.0 Cost implication for new specification - Case Study

13.1 Two case study have been done regarding cost implications forthe projects involving earthwork and blanketing

13.2 Chandigarh Ludhiana Single Line : The work is presentlygoing on with GE-G1 2003 specifications. The soil being used inembankment fill is SM type i.e. SQ 2 type as per new specification.The blanket is manufactured by Crushing and mixing methodologyand found as per specification. The cost of the material includingexecution is as under

Type of Material Rate (in Rs./cum)

Rate of blanket material 948 (Actual)

Rate of SQ2 Soil (SM Type) 133 (Actual)

Analysis has been done for Bank Height of 1.75m ( maximumdepth of variation in Formation Layers)

The total cost as per GE- G 1 2003 is Rs 87,54,070

The total cost as per new specification is Rs 52,53,645

Hence there is 40% saving if the work is executed as per newspecification

13.3 Manmadurai-Virudunagar Gauge conversion : The workis presently going on with GE-G1 2003 specifications. The soil beingused in embankment fill is SM type i.e. SQ 2 type as per newspecification. The blanket is manufactured by blending methodologyand found as per specification The cost of the material includingexecution is as under

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Type of Material Rate (in Rs./cum)

Rate of blanket material 825 (Actual)

Rate of SQ2 Soil (SC Type) 180 (Actual)

Analysis has been done for Bank Height of 1.75m ( maximumdepth of variation in Formation Layers)

The total cost as per GE- G 1 2003 is Rs 82,82,025

The total cost as per new specification is Rs 55,11,750

Hence there is 33.4% saving if the work is executed as per newspecification

The cost implication has been worked out for RVNL projects alsoand it was found that there is huge savings with the implementationof new specifications. The saving has arisen because of lessthickness of blanket material provided over the embankment fill/prepared subgrade

14.0 Conclusions :14.1Running of heavy axle load requires design and construction ofstable & durable formation to minimize in service maintenance. Properselection of construction material viz. embankment soil, top layer ofsubgrade/prepared subgrade, blanket material is necessary basedon some rational criteria like CBR value, size gradation etc.

14.2Ground improvement in case of weak sub-soil strata and adequatequality assurance tests are essential to achieve desired quality offormation. The thickness requirement of sub-structure layers betweenballast & sub-grade specially weak sub-grade for higher axle load isof the order of one metre or even more. Part of the blanket requirementcan be substituted with good quality of soil as prepared subgradelayer resulting in economy as well as strength requirement.Mechanical production of blanket material to achieve desiredspecification is a viable alternative.

14.3Recommended Multi-layer formation systems based on CBRvalue is better option and will result in reduced blanket requirementand economic formation system as per requirement of heavy axleloads including DFC. Thus, the new formation specifications are betterfor heavy axle load including DFC which will require minimummaintenance during operation.

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References :(i) AREMA Manual, 2002

(ii) Australian Railway (ARTC) Code RTS 3430, March 2006

(iii) Guidelines of Earthwork in Railway Projects, RDSO, No. GE:G-1,July, 2003

(iv) Heukelom and Klomp (1962): ‘Dynamic Testing as a means ofcontrolling Pavements during and after Construction, Proceedingsof 1st International Conference on Structural Design of AsphaltPavements.

(v) State Of The Art Report On Provision Of Railway Formation, RDSOReport No. GE – 35.

(vi) State of the Art Report on sub-grade stress and design of tracksubstructure, Civil Engineering Report No. C – 271.

(vii) IRC:37- ‘Guidelines & Design of Flexible Pavement’, Indian RoadCongress.

(viii) ORE Reports D – 71, RP – 12 & D-117, RP 28.

(ix) ‘Modern Railway Track’, Esveld, Conrad MRT Productions NL, TUDelft, Second Edition 2001.

(x) ‘Procedure For Railway Track Granular Layer ThicknessDetermination’, Dingqing Li, Theodore R. Sussmann Jr., and ErnestT. Selig, Report no. R-898, October, 1996, Assosiation of AmericanRailroads ( AAR), TTC, Pueblo, Colorado, USA.

(xi) ‘Design Issues and Sub-grade Assessment for the Rawang-IpohHigh Speed Track’, Sondhi, J.S., Dasari, G. Rao, and Tan, Siew Ann,RailTech Conference, Kuala Lumpur, Malaysia, 2003.

(xii) Track Compendium– Formation, Permanent Way, Maintenance,Economics, by Dr. Bernhard Lichtberger, 2005, Eurail Press,Hamburg, Germany.

(xiii) UIC Code 719: ‘Earthworks and Track-bed layers for Railway Line’,Third ed., 2008

* * *

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Impact of Increasing Axle Load on Fatigue Life ofStandard Steel Girder Bridges – A Study Based

on Revised Fatigue Provisions

R.K. Goel*H.O. Narayan**

*Director/Steel Bridges - I/RDSO**Asstt. Design Engineer/B&S Directorate/RDSO

Synopsis: Increasing the axle load of railway wagons has been amatter of concern for railway engineers as it’s effect on residualfatigue life of steel girder bridges was not clearly understood. Therehad been no accepted provisions or guidelines to assess the fatiguelife of steel girder bridges till RDSO discussed the “Draft Provisionsfor Fatigue Assessment” in 78th BSC. The simplified approach ofthese provisions has been used to assess the design fatigue life ofstandard plate girder bridges for MBG loading and new 25 t Loading-2008 for different average annual GMTs of the routes. It has beenfound that the reduction in design fatigue life depends on the bridgespan. The design fatigue life gets improved substantially, if thecoefficient of dynamic impact (CDA) is controlled either by imposingspeed restriction or by improving track maintenance on girder bridges.

1.0 Introduction

1.1 Indian Railway has recently permitted over utilization of carryingcapacity of it’s wagons for generating extra revenue. This hasincreased axle loads of wagons. The magnitude of trailing load (TLD)has been increased from Carrying Capacity (CC) to CC+6+2 andsubsequently to CC+8+2. A new loading standard 25 t loading -2008has also been included in existing IRS Bridge Rules and this loadinghas been permitted on existing bridges. RDSO has also issuedguidelines for running 25 t loading - 2008 on existing bridges. It is tobe noted that most of the railway bridges have been designed forIndian Railways standard loadings such as BGML, RBG & MBGwhich are having varying equivalent uniformly distributed loads. The

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net effect of increased trailing load is to increase the number of cyclesof maximum stress range to which the members are subjected andtherefore greater fatigue damage is caused therein. The ultimate effectof running heavy axle load is thus, to reduce the residual fatigue lifeof the existing bridges.

1.2 The issue of revision of fatigue provisions in IRS steel bridgecode had been under discussion for quite some time. Detailed studieshave been carried out by RDSO on the issue and draft provisionshave been issued for adoption. These provisions have also beendiscussed in 78th Bridge Standard Committee and as per RailwayBoard Orders the workability and suitability of these provisions isbeing ascertained before final adoption. In this connection a studyon assessment of fatigue life of existing standard steel girders hasbeen done by RDSO based on the simplified approach of the draftrevised provisions. This paper presents the approach used and theresults of study, showing the extent to which the fatigue life ofstandard steel girders has been affected by running 25 t axle loadvis-à-vis MBG loading.

2.0 Simplified Approach of Revised Irs Provisions

2.1 Fatigue stress spectra

2.1.1 For the simplified fatigue loading the following procedure isadopted to determine the design stress spectrum.

2.1.2 The recommended equivalents for train loads shall be adoptedin accordance with existing provisions of IRS Bridge Rules, includingthe dynamic impact factor Φ, which is calculated as (1.0 + CDA),where CDA is the coefficient of Dynamic Augment as specified inIRS Bridge Rules.

2.1.3 The maximum stress σP,max and the minimum stress σP,min shouldbe determined for a detail or structural connection. The σP,max is forDead Load + Full Live Load with dynamic impact factor ‘φ’ whereasthe σP,min is for dead load effects only.

2.1.4 The reference stress range ΔσP for determining the damagedue to the stress spectrum should be obtained from:

ΔσP = | ΔσP,max - ΔσP,min |

2.1.5 The damage effects of the stress range spectrum may be

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represented by the damage equivalent stress range related to 2 millioncycles as

ΔσE,2 = λ * Φ * ΔσP

Where,λ is the damage equivalence factor, andΦ is the dynamic impact factor (1.0 + CDA),CDA is the coefficient of Dynamic Augment as specifiedin Bridge Rules

2.1.6 The value of damage equivalence factor, ‘λ’ are specific tothe type of loading and the values are dependent on loaded length,‘L’ which is defined in para 2.3.3.

2.2 Fatigue assessmentThe fatigue assessment shall be carried out by ensuring thesatisfaction of the following criteria:

γFf *ΔσE,2 ≤ ΔσC / γMf

Where,

ΔσC is the reference value of the fatigue strength at NC = 2million cycles

γMf is the partial safety factor for material

γFf is the partial safety factor for loads

2.3 Damage equivalence factors

2.3.1 The damage equivalent factor for railway bridges shouldbe determined from: λ = λ1 * λ2 * λ3 * λ4

subject to the condition that λ ≤ λmax

where

λ1

is a factor that takes into account the damaging effect

of traffic and depends on the base length of the longestloop of the influence line diagram

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λ2 is a factor that takes into account the annual trafficvolume in million tonnes

λ3 is a factor that takes into account the design life of thebridge in years

λ4 is a factor to be taken into account when the bridgestructure is loaded on more than one track

λmax is the maximum l value taking into account the fatiguelimit and is equal to 1.4

2.3.2 The loaded length for the determination of the appropriate λ1

should be taken as follows:

(a) for moments:- For a simply supported span, the span length, L- For cross girders supporting rail bearers (or stiffeners),the sum of the spans of the rail bearers (or stiffeners)carried by the cross girder.

(b) for shear for a simply supported span- For the support section, the span length- For the mid-span section, 0.4 * the span underconsideration

(c) In other cases- the same as for moments

(d) for truss members- base length of the largest loop of Influence line diagram

2.3.3 The value of λ2, in terms of the annual volume of traffic may beobtained from the following expression:

λ2 = 0.5193 * Ta0.2036

Where Ta is the annual volume of traffic expressed in milliontonnes.

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2.3.4 Unless otherwise specified by the competent authority the valueof λ3 will be taken as 1.04 for a design life of 120 years. For othervalues of design life the corresponding value may be calculated fromthe following expression where LD is the design life in years

λ3 = 0.3899 * LD0.2048

2.3.5 The value of λ4, assuming 15% of the total traffic on both trackscrosses whilst on the bridge, unless specified otherwise by thecompetent authority, shall be obtained from

λ4 = 0.7926 * a2 - 0.7280 * a + 0.9371

where

a = Δσ1 / Δσ1+2

Δσ1 = Stress range at the section being checked due totrain on one track.

Δσ1+2 = Stress range at the same section due to train loadon two tracks.

The values of λ4 may be calculated for other proportions ofcrossing traffic from

λ4 = 5 n + (1 - n) [a5 + (1 - a)5]

where

n is the proportion of traffic that crosses whilst on the bridge.

2.3.6 The value of λ should not exceed λmax which is specified as 1.4.

3.0 Determination of λλλλλ1 Parameters3.1 The fatigue life assessment has been done for MBG loading and25t loading as given in IRS Bridge Rule. The fatigue load model forthese loading have been developed and λ1 parameters worked out inassociation with IIT/Roorkee using Artificial Neural Network Technique.

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3.2 The value of λ1 is to be obtained from tables 1 & 2 for MBGloading and 25t loading - 2008 respectively as a function of the loadedlength. These values have been worked out as per the train typesincluded in the respective standard fatigue load models for MBGloading and 25t loading. The loaded length shall depend upon theinfluence line diagram of the structural detail/connection underconsideration.

4.0 Assessment Method and Assumptions

(i) Maximum stress range taken as the difference of dead loadstress and the maximum stress likely to come in the memberwith DL, Impact load and live load. The maximum bendingstresses due to equivalent uniformly distributed load for IRSloadings given in Bridge Rules have been worked out andthe maximum stress range calculated.

(ii) In the analysis of plate girder only the bending stresses dueto maximum bending moment have been taken intoconsideration to find out the maximum stress range and thedesign fatigue life of spans has been assessed.

(iii) Occasional loads have not been considered.

(iv) For plate girders, the loaded length for considering λ1 hasbeen taken, as effective span length.

(v) GMT factor is taken as per proposed fatigue criteria in 78thBSC.

(vi) Fatigue categories are chosen as per the Table – 3 which isbased on the tables given in draft provisions, discussed in78th BSC and the engineering judgment applied. Theanalyzed fatigue life may vary on this account.

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Tab

le 1

: λλλλ λ

1 fo

r M

BG

Lo

adin

g

Span

(m)

Trai

n-1

Trai

n-2

Trai

n-3

Trai

n-4

Trai

n-5

Trai

n-6

Trai

n-7

Trai

n-8

Trai

n-9

Trai

n-10

0.50

1.19

961.

3377

1.33

421.

1477

1.33

531.

5986

1.56

811.

3336

1.26

721.

2849

1.00

1.17

751.

3266

1.31

111.

1360

1.33

201.

5893

1.56

981.

3318

1.25

901.

2748

1.50

1.16

151.

3106

1.28

201.

1218

1.33

141.

5756

1.57

301.

3293

1.25

521.

2634

2.00

1.14

701.

2903

1.26

741.

1039

1.33

181.

5650

1.57

691.

3267

1.25

371.

2473

2.50

1.12

881.

2651

1.25

591.

0820

1.33

171.

5617

1.58

091.

3252

1.25

231.

2290

3.00

1.10

501.

2339

1.24

601.

0502

1.33

031.

5618

1.58

391.

3254

1.25

021.

2174

3.50

1.07

411.

1963

1.23

671.

0063

1.32

811.

5614

1.58

561.

3270

1.24

741.

2121

4.00

1.03

861.

1537

1.22

700.

9639

1.32

541.

5620

1.58

591.

3291

1.24

421.

2077

4.50

0.99

861.

1100

1.21

570.

9294

1.32

221.

5627

1.58

561.

3312

1.24

061.

2024

5.00

0.95

031.

0694

1.20

140.

8953

1.31

881.

5636

1.58

601.

3327

1.23

671.

1961

6.00

0.86

990.

9994

1.16

060.

8247

1.31

121.

5663

1.58

761.

3362

1.22

861.

1843

7.00

0.84

510.

9574

1.13

410.

7469

1.30

311.

5590

1.58

231.

3184

1.22

161.

1666

8.00

0.83

000.

9389

1.10

750.

6797

1.29

571.

5299

1.57

361.

3142

1.21

731.

1446

9.00

0.81

750.

9282

1.06

280.

6437

1.28

841.

4952

1.56

211.

3117

1.21

461.

1102

2.97

Span

(m)

Trai

n-1

Trai

n-2

Trai

n-3

Trai

n-4

Trai

n-5

Trai

n-6

Trai

n-7

Trai

n-8

Trai

n-9

Trai

n-10

10.0

00.

8676

0.95

881.

0191

0.56

001.

1653

1.29

611.

3417

1.11

671.

1238

1.01

27

12.5

00.

8462

0.95

490.

9896

0.54

211.

1416

1.24

691.

2912

1.11

271.

1205

0.95

85

15.0

00.

8263

0.93

760.

9505

0.54

391.

1252

1.19

111.

2392

1.10

871.

1114

0.93

02

17.5

00.

8162

0.91

680.

9056

0.55

631.

0956

1.14

571.

1787

1.10

471.

0814

0.91

70

20.0

00.

8558

0.90

870.

8477

0.59

051.

1604

1.18

081.

1717

0.98

811.

1445

0.89

85

25.0

00.

7783

0.79

770.

7779

0.58

461.

1146

1.07

701.

1297

0.97

401.

0955

0.86

07

30.0

00.

7553

0.77

000.

7163

0.55

511.

0888

1.03

121.

0675

0.96

461.

0616

0.81

49

35.0

00.

7307

0.72

250.

6843

0.51

031.

0649

0.99

181.

0005

0.97

291.

0455

0.77

45

40.0

00.

7162

0.70

400.

6632

0.53

911.

0403

0.90

960.

9651

0.97

871.

0377

0.74

37

45.0

00.

6884

0.67

420.

6497

0.53

671.

0243

0.85

600.

9229

0.97

810.

9996

0.72

34

50.0

00.

6494

0.65

550.

6411

0.51

541.

0048

0.79

930.

8834

0.97

390.

9546

0.71

01

60.0

00.

5494

0.63

840.

6346

0.43

150.

9696

0.71

290.

8208

0.96

190.

8765

0.68

47

70.0

00.

5282

0.58

490.

6367

0.42

110.

8868

0.66

920.

7579

0.94

740.

8288

0.66

58

80.0

00.

5020

0.53

980.

6156

0.42

190.

8213

0.65

060.

7126

0.92

860.

8037

0.65

16

90.0

00.

4739

0.51

280.

5324

0.41

270.

7781

0.64

560.

6807

0.90

480.

7785

0.63

67

100.

000.

4521

0.48

930.

5039

0.40

470.

7205

0.64

160.

6593

0.88

360.

6921

0.62

72

Tab

le 1

: λλλλ λ 1

M

BG

Lo

adin

g (

Co

nti

nu

ed)

2.98

Tab

le 2

: λλλλ λ 1

for

25 T

Lo

adin

g

Span

(m)

Trai

n-1

Trai

n-2

Trai

n-3

Trai

n-4

Trai

n-5

Trai

n-6

Trai

n-7

Trai

n-8

Trai

n-9

Trai

n-10

Trai

n-11

0.50

1.22

781.

3574

1.50

430.

6903

1.43

691.

6074

1.31

311.

3236

1.39

231.

3121

1.29

30

1.00

1.20

421.

3435

1.48

860.

6762

1.42

841.

6003

1.31

601.

3199

1.38

831.

3031

1.28

89

1.50

1.18

621.

3283

1.47

080.

6625

1.41

981.

5970

1.32

301.

3156

1.38

421.

2998

1.28

47

2.00

1.17

071.

3124

1.45

090.

6500

1.41

141.

5948

1.32

971.

3106

1.38

041.

2988

1.28

01

2.50

1.15

561.

2951

1.42

790.

6383

1.40

381.

5928

1.33

011.

3049

1.37

661.

2982

1.27

46

3.00

1.14

101.

2750

1.40

010.

6246

1.39

711.

5910

1.32

181.

2987

1.37

121.

2965

1.26

81

3.50

1.12

271.

2503

1.36

600.

6073

1.39

151.

5895

1.31

321.

2922

1.36

391.

2932

1.26

05

4.00

1.09

101.

2195

1.32

740.

5859

1.38

651.

5889

1.31

321.

2858

1.36

171.

2884

1.25

15

4.50

1.03

931.

1835

1.29

240.

5631

1.38

111.

5906

1.31

541.

2802

1.36

441.

2829

1.24

12

5.00

0.97

651.

1453

1.26

560.

5443

1.37

241.

5930

1.31

821.

2761

1.36

741.

2778

1.22

96

6.00

0.89

681.

0749

1.21

280.

5239

1.34

941.

5961

1.32

161.

2728

1.36

101.

2736

1.20

39

7.00

0.87

961.

0144

1.14

930.

5148

1.33

711.

5981

1.32

151.

2705

1.33

071.

2669

1.17

42

8.00

0.86

920.

9717

1.09

110.

5069

1.30

731.

5971

1.32

041.

2680

1.28

701.

2586

1.14

16

9.00

0.86

260.

9473

1.05

370.

4997

1.26

051.

5930

1.31

861.

2665

1.25

151.

2494

1.11

63

2.99

Span

(m)

Trai

n-1

Trai

n-2

Trai

n-3

Trai

n-4

Trai

n-5

Trai

n-6

Trai

n-7

Trai

n-8

Trai

n-9

Trai

n-10

Trai

n-11

10.0

00.

9047

0.96

821.

0109

0.54

561.

0825

1.35

031.

1921

1.17

081.

0788

1.10

920.

9719

12.5

00.

8925

0.96

200.

9572

0.53

151.

0711

1.30

021.

2022

1.17

431.

0851

1.08

450.

9463

15.0

00.

8806

0.91

980.

9468

0.52

201.

0534

1.24

321.

1971

1.18

771.

0566

1.03

170.

9249

17.5

00.

8274

0.89

370.

9165

0.51

571.

0076

1.20

111.

1833

1.19

170.

9964

0.99

460.

8925

20.0

00.

8262

0.89

950.

8962

0.52

530.

9897

1.21

241.

1808

1.15

900.

9845

0.94

220.

8102

25.0

00.

8065

0.87

120.

8906

0.51

040.

9690

1.16

501.

1806

1.15

910.

9911

0.93

020.

7540

30.0

00.

7899

0.77

740.

8768

0.50

910.

9401

1.10

041.

1797

1.15

880.

9804

0.92

410.

7012

35.0

00.

7706

0.76

430.

8657

0.50

550.

9058

1.04

151.

1781

1.15

770.

9472

0.89

380.

6568

40.0

00.

7554

0.72

900.

7835

0.50

190.

8702

0.97

861.

1759

1.15

460.

9056

0.85

500.

6224

45.0

00.

7270

0.70

370.

7470

0.49

550.

8395

0.97

661.

1733

1.14

970.

8677

0.81

560.

6101

50.0

00.

6863

0.68

140.

7148

0.48

770.

8171

0.97

331.

1706

1.14

440.

8364

0.77

890.

6778

60.0

00.

5832

0.65

520.

6815

0.48

130.

8197

0.92

411.

1637

1.13

180.

7877

0.73

920.

6610

70.0

00.

5486

0.60

460.

6601

0.48

230.

8529

0.85

001.

1552

1.11

640.

8249

0.70

860.

6352

80.0

00.

5090

0.55

700.

6458

0.48

610.

7976

0.77

031.

1484

1.09

920.

7609

0.67

290.

6087

90.0

00.

4738

0.53

670.

5849

0.49

990.

7276

0.72

451.

1400

1.07

430.

6793

0.65

790.

5898

100.

000.

4532

0.51

730.

5554

0.51

130.

6520

0.69

211.

1286

1.03

130.

6131

0.64

600.

5724

Tab

le 2

: λλλλ λ 1

for

25 T

Lo

adin

g (

Co

nti

nu

ed)

2.100

Table – 3 Fatigue Categories Adopted for Member Detail/Connections

S. Member detail or Fatigue categoryNo. connection to be Remark

assessed Category Reference

1 Stringer, X-girder & Plate 100 Details 5 & 6 Bendinggirders (welded type) of Table 9.2 stresses at mid

of spanStringer, X-girder & 80 Detail 8 ofPlate girders (rivetted type) Table 9.1

2 Fillet weld of web-flange 80 Detail 8 Shear stressconnection of stringer/x- of Table 9.5 at throatgirder area of weld.

3 Gusset connections 80 Detail 8 of Axial stressesTable 9.1 on net area.

4 Stringer and x-girder 100 Detail 11 of Shear stress onconnection Table 9.1 shank area of

rivet/bolt

5.0 Fatigue Life Assessed5.1 Based on above assumptions, the design calculations forassessment of fatigue life of plate girder bridges are given in Table -4 for MBG loading and in Table - 5 for 25t loading.

5.2 It is to be noted that the annual GMT for a particular route maynot be comprised of the trains causing maximum stress range.Situation may vary route wise and partial GMT may be due to trainscausing much lower stress range. In such cases a more detailedfatigue assessment would be required taking into consideration therepresentative load model of actual set of trains running on the route.

5.3 It is further to be observed that due to change of loading, thel1values and the maximum design stress-ranges have increasedmarginally. However, the effect on design fatigue life has beenconsiderable on higher spans as compared to smaller spans.

2.101

Tab

le -

4 A

sses

sed

fat

igu

e lif

e o

f st

and

ard

pla

te g

ird

er b

rid

ges

(M

BG

Lo

adin

g)

510

2030

4050

0.72

10.

830

0.95

61.

038

1.10

11.

152

12.2

m M

BGB-

1600

911

8.33

13.1

1.28

64.8

0232

.533

16.3

3310

.914

8.20

06.

568

(4 m

illion

)

12.2

m M

BGB-

1601

295

.75

13.1

1.28

182.

219

91.4

8045

.926

30.6

9023

.057

18.4

69 (1

0 m

illion

)

18.3

m M

BGB-

1601

010

9.35

19.4

1.18

141.

727

71.1

5235

.721

23.8

7017

.933

14.3

65 (4

milli

on)

18.3

m M

BGB-

1601

384

.22

19.4

1.18

507.

201

254.

633

127.

834

85.4

2664

.177

51.4

09(1

0 m

illion

)

24.4

m M

BGB-

1601

193

.02

25.6

1.12

539

4.14

019

7.87

299

.339

66.3

8349

.871

39.9

49 (4

milli

on)

24.4

m M

BGB-

1600

584

.15

25.6

1.12

564

2.92

732

2.77

216

2.04

310

8.28

581

.351

65.1

66(1

0 m

illion

)

12.2

m B

GM

LB-

1100

311

2.88

13.1

1.28

27.4

4013

.776

6.91

64.

622

3.47

22.

781

(2m

illion

)

18.3

m B

GM

LB-

1100

411

1.86

19.4

1.18

42.6

7121

.422

10.7

557.

187

5.39

94.

325

(2

milli

on)

24.4

m B

GM

LB-

1100

510

7.2

25.6

1.12

566

.311

33.2

9016

.713

11.1

688.

390

6.72

1(2

milli

on)

Std.

RD

SO D

rg.

Stre

ss R

ange

Load

edLo

ading

Span

No.

Rm

axLe

ngth

‘L'

fact

or,

(N/m

m2)

(m)

Lam

da1

Des

ign

Life

(yea

rs) f

or G

MT

& co

rresp

ondi

ng a

vera

ge ro

ute

GM

T fa

ctor

(Lam

da2)

σ

2.102

Tab

le -

5 A

sses

sed

fat

igu

e lif

e o

f st

and

ard

pla

te g

ird

er b

rid

ges

(25

t L

oad

ing

)

510

2030

4050

0.72

10.

830

0.95

61.

038

1.10

11.

152

12.2

m M

BGB-

1600

911

8.31

13.1

1.29

62.4

3731

.346

15.7

3710

.516

7.90

06.

329

(4 m

illion

)

12.2

m M

BGB-

1601

295

.73

13.1

1.29

175.

603

88.1

5944

.259

29.5

7622

.220

17.7

99(1

0 m

illion

)

18.3

m M

BGB-

1601

011

4.75

19.4

1.21

101.

106

50.7

5925

.483

17.0

2912

.793

10.2

48(4

milli

on)

18.3

m M

BGB-

1601

388

.38

19.4

1.21

361.

811

181.

642

91.1

9160

.938

45.7

8136

.673

(10

milli

on)

24.4

m M

BGB-

1601

198

.325

.61.

1823

8.42

811

9.69

960

.093

40.1

5730

.169

24.1

67(4

milli

on)

24.4

m M

BGB-

1600

588

.92

25.6

1.18

389.

066

195.

325

98.0

6065

.529

49.2

2939

.435

(10

milli

on)

12.2

m B

GM

LB-

1100

311

2.86

13.1

1.29

26.4

4013

.274

6.66

44.

453

3.34

52.

680

(2m

illion

)

18.3

m B

GM

LB-

1100

411

7.38

19.4

1.21

30.4

4615

.285

7.67

45.

128

3.85

23.

086

(2 m

illion

)

24.4

m B

GM

LB-

1100

511

3.28

25.6

1.18

40.1

2220

.143

10.11

26.

758

5.07

74.

067

(2 m

illion

)

Std.

RD

SO D

rg.

Stre

ss R

ange

Load

edLo

ading

Span

No.

Rm

axLe

ngth

‘L'

fact

or,

(N/m

m2)

(m)

Lam

da1

Des

ign

Life

(yea

rs) f

or G

MT

& co

rresp

ondi

ng a

vera

ge ro

ute

GM

T fa

ctor

(Lam

da2)

σ

2.103

6.0 Effect of Speed on the Assessed Design Fatigue Life6.1 It is evident from the perusal of Table 4 & 5 that the assessedfatigue life is quite low for high GMT routes and the spans designedfor 2 million cycles as per old fatigue provisions based on stressratio concept. This is apparently due to the fact that the stressranges considered in analysis are based on full CDA (Coefficient ofDynamic Augment) which is applicable for a speed 125 kmph forgoods trains. Practically, goods trains do not run with a speed morethan 100 kmph. Therefore, the design fatigue life has been re-assessedwith reduced stress ranges corresponding to a sectional speed of100 kmph by proportionately reducing the maximum design stressrange. The results for re-assessed design life for MBG loading and25t loading are shown in table 6 & 7 respectively.

6.2 It is further noted that the new 25t loading has been permittedwith a sectional speed of 75 kmph due to strength considerations.Accordingly, the fatigue life of bridges with new 25t loading at 75kmph has been again worked out with reduced CDA valuecorresponding to 75 Kmph and the results are given in Table – 8.

7.0 Limitation of the Results ObtainedThe results of analysis may be interpreted keeping in view thefollowing:

i) Assessment is based on average GMT of the route over thelife span of the bridge. The GMT being carried in presentmay be actually different.

ii) The GMT may be comprised of no. of trains which may notgive the maximum stress range.

iii) Partial factor of safety is assumed as 1.0 for analysis ofexisting bridges.

v) It is assumed that the physical condition of the bridge isotherwise sound from other considerations and effect ofcorrosion, pitting and other defects developed during servicehave not been accounted for.

2.104

510

2030

4050

0.72

10.

830

0.95

61.

038

1.10

11.

152

12.2

m M

BGB-

1600

910

9.8

13.1

1.28

93.3

7846

.879

23.5

3515

.727

11.8

159.

465

(4 m

illion

)

12.2

m M

BGB-

1601

288

.813

.11.

2826

3.26

113

2.16

666

.352

44.3

4033

.311

26.6

84(1

0 m

illion

)

18.3

m M

BGB-

1601

010

2.5

19.4

1.18

194.

372

97.5

8248

.989

32.7

3724

.594

19.7

01(4

milli

on)

18.3

m M

BGB-

1601

378

.919

.41.

1869

7.51

035

0.17

417

5.80

011

7.47

988

.258

70.6

98(1

0 m

illion

)

24.4

m M

BGB-

1601

187

.725

.61.

125

525.

457

263.

798

132.

436

88.5

0066

.487

53.2

59(4

milli

on)

24.4

m M

BGB-

1600

579

.31

25.6

1.12

585

8.57

443

1.03

421

6.39

414

4.60

610

8.63

787

.024

(10

milli

on)

12.2

m B

GM

LB-

1100

310

4.7

13.1

1.28

39.6

1919

.890

9.98

66.

673

5.01

34.

016

(2 m

illion

)

18.3

m B

GM

LB-

1100

410

4.8

19.4

1.18

58.6

6629

.452

14.7

869.

881

7.42

35.

946

(2 m

illion

)

24.4

m B

GM

LB-

1100

510

1.1

25.6

1.12

588

.272

44.3

1622

.248

14.8

6711

.169

8.94

7(2

milli

on)

Std.

RD

SO D

rg.

Stre

ss R

ange

Load

edLo

ading

Span

No.

Rm

axLe

ngth

‘L'

fact

or,

(N/m

m2)

(m)

Lam

da1

Des

ign

Life

(yea

rs) f

or G

MT

& co

rresp

ondi

ng a

vera

ge ro

ute

GM

T fa

ctor

(Lam

da2)

Tab

le –

6 A

sses

sed

fati

gu

e lif

e fo

r d

iffe

ren

t GM

Ts (M

BG

Lo

adin

g) w

ith

sec

tio

nal

sp

eed

of 1

00 k

mp

hG

MAm

f = 1

,G

MAf

F =

1,Fa

tcat

=10

010

080

80C

DA

with

100

Km

ph

σ

2.105

Tabl

e – 7

Ass

esse

d fa

tigue

life

for d

iffer

ent G

MTs

(25

t Loa

ding

) with

sec

tiona

l spe

ed o

f 100

km

ph

510

2030

4050

0.72

10.

830

0.95

61.

038

1.10

11.

152

12.2

m M

BGB-

1600

910

9.7

13.1

1.28

90.2

9745

.332

22.7

5815

.208

11.4

259.

152

(4 m

illion

)

12.2

m M

BGB-

1601

288

.813

.11.

2825

3.44

512

7.23

863

.878

42.6

8732

.069

25.6

89(1

0 m

illion

)

18.3

m M

BGB-

1601

010

7.5

19.4

1.18

139.

052

69.8

0935

.046

23.4

2017

.595

14.0

94(4

milli

on)

18.3

m M

BGB-

1601

382

.819

.41.

1849

7.48

624

9.75

512

5.38

683

.789

62.9

4850

.424

(10

milli

on)

24.4

m M

BGB-

1601

192

.725

.61.

125

317.

497

159.

395

80.0

2253

.475

40.1

7432

.181

(4 m

illion

)

24.4

m M

BGB-

1600

583

.825

.61.

125

519.

735

260.

925

130.

993

87.5

3765

.763

52.6

79(1

0 m

illion

)

12.2

m B

GM

LB-

1100

310

4.7

13.1

1.28

38.1

4219

.149

9.61

36.

424

4.82

63.

866

(2 m

illion

)

18.3

m B

GM

LB-

1100

410

9.9

19.4

1.18

41.9

9121

.081

10.5

837.

072

5.31

34.

256

(2 m

illion

)

24.4

m B

GM

LB-

1100

510

6.8

25.6

1.12

553

.493

26.8

5513

.482

9.01

06.

769

5.42

2(2

milli

on)

Std.

RD

SO D

rg.

Stre

ss R

ange

Load

edLo

ading

Span

No.

Rm

axLe

ngth

‘L'

fact

or,

(N/m

m2)

(m)

Lam

da1

Des

ign

Life

(yea

rs) f

or G

MT

& co

rresp

ondi

ng a

vera

ge ro

ute

GM

T fa

ctor

(Lam

da2)

GM

Amf =

1,

GM

AfF

= 1,

Fatc

at =

100

100

8080

CD

A w

ith 1

00 K

mph

σ

2.106

510

2030

4050

0.72

10.

830

0.95

61.

038

1.10

11.

152

12.2

m M

BGB-

1600

910

1.15

13.1

1.28

134.

198

67.3

7233

.823

22.6

0216

.980

13.6

02(4

milli

on)

12.2

m M

BGB-

1601

281

.84

13.1

1.28

377.

543

189.

540

95.1

5663

.588

47.7

7138

.267

(10

milli

on)

18.3

m M

BGB-

1601

010

0.2

19.4

1.18

196.

021

98.4

0949

.405

33.0

1524

.803

19.8

68(4

milli

on)

18.3

m M

BGB-

1601

377

.219

.41.

1870

0.29

735

1.57

317

6.50

211

7.94

888

.610

70.9

81(1

0 m

illion

)

24.4

m M

BGB-

1601

187

25.6

1.12

543

2.82

621

7.29

410

9.08

972

.899

54.7

6643

.870

(4 m

illion

)

24.4

m M

BGB-

1600

578

.725

.61.

125

706.

208

354.

541

177.

992

118.

944

89.3

5871

.580

(10

milli

on)

12.2

m B

GM

LB-

1100

396

.513

.11.

2856

.800

28.5

1614

.316

9.56

77.

187

5.75

7(2

milli

on)

18.3

m B

GM

LB-

1100

410

2.5

19.4

1.18

59.0

1829

.629

14.8

759.

940

7.46

85.

982

(2 m

illion

)

24.4

m B

GM

LB-

1100

510

0.3

25.6

1.12

572

.686

36.4

9118

.320

12.2

429.

197

7.36

7(2

milli

on)

Std.

RD

SO D

rg.

Stre

ss R

ange

Load

edLo

ading

Span

No.

Rm

axLe

ngth

‘L'

fact

or,

(N/m

m2)

(m)

Lam

da1

Des

ign

Life

(yea

rs) f

or G

MT

& co

rresp

ondi

ng a

vera

ge ro

ute

GM

T fa

ctor

(Lam

da2)

GM

Amf =

1,

GM

AfF

= 1,

Fatc

at =

100

100

8080

CD

A w

ith 7

5 Km

ph

Tab

le –

8 A

sses

sed

fat

igu

e lif

e fo

r d

iffe

ren

t G

MTs

(25

t L

oad

ing

) w

ith

sec

tio

nal

sp

eed

of

75 k

mp

h

σ

2.107

8.0 Conclusions8.1 The design fatigue life of standard plate girders is found reducedas a result of running of 25t loading – 2008 vis-à-vis existing MBGloading.

8.2 Reduction in design fatigue life is nominal (3-4%) for smallerspan (12.2m) and significantly high (40%) for higher span (24.4m).

8.3 Route GMT and sectional speed are important parameters whichaffect the design fatigue life considerably. The Effect of reducingCDA is to improve the design fatigue life by reducing the maximumdesign stress range and the reduction is substantial.

8.4 Plate girders designed for 10 million cycles as per existing fatiguecriteria in IRS Steel Bridge Code give better estimate of fatigue lifeas compared to those designed for 4 million cycles.

8.5 Plate girders designed for 2 million cycles as per existing fatiguecriteria in IRS Steel Bridge Code gives very low estimate of fatiguelife and the same need to be verified again using detailed fatigue lifeanalysis with respect to train loads and actual GMT on the routeswhere these girders are provided.

* * *

.

Notes

Notes