Innovative solution for crossing larger spaces like railway yard

A Technical paper on :-

INNOVATIVE SOLUTION FOR CROSSING LARGER SPACES LIKE RAILWAY YARD – A CASE STUDY ON BARDHAMAN

CABLE STAYED ROB.

By Rajesh Prasad, IRSE

Chief Project Manager (M) &

Group General Manager RVNL, Kolkata

To be presented during the seminar on 03.06.2016 organised by Consulting Engineeres Association of India (CEAI)

INNOVATIVE SOLUTION FOR CROSSING LARGER SPACES LIKE RAILWAY YARD – A CASE STUDY ON BARDHAMAN CABLE STAYED ROB.

RAJESH PRASAD, IRSE, GROUP GENERAL MANAGER(M)/RVNL/KOLKATA

(INDIA)

ABSTRACT: It was a sunny morning on 14th April, 1853 when the wheels of the Indian Railway train turned for the first time on its inaugural run from Mumbai to Thane. After over a period of time the wheels of Indian Railways have gathered momentum and stood the test of time and are running at full throthene. During its period of more than 160 years a lot of developments have taken place. The requirement from the passenger point of view and operational point of view have gone up. In the urban area crossing the yard through ROB also need augmentation in view of the increased volume of road traffic and also for future yard remodelling and passenger amenities works. Thus, the space available at Railway yard are required to be used properly for innovative solutions for crossing such yards. The general requirements of 2 lane ROB have now been changed to 4 lane ROB and also no construction inside the yard. Meaning thereby the space inside the yard shall be used for future yard remodelling, future passenger amenities work like platform extension etc. It is a fact that construction activities with proper quality and safety inside the yard sometimes become difficult. At Barddhaman, recently 4 lane cable stayed bridge has been implemented and the paper deals about the innovative solution considered for the said bridge construction.

1.0 Introduction: In Howrah-Delhi Rajdhani route over a busy yard at Barddhaman an engineering

challenge was confronted in the form of rebuilding of an existing dilapidated 2 lane ROB by construction of a new 4 lane ROB. Barddhaman yard is one of the busiest yard of Eastern Railway and Rajdhani route over Barddhaman station spanning across 8 platforms and 10 tracks. There are numerous constraints, such as restriction of maximum height of the road surface clearances, and very busy movement of rolling stock over the yard. Such constraints resulted in asymmetric cable stayed bridge of 188.429 m span with monolithic RCC in back span, composite deck and steel pylon. Erection of main girder with cables has commenced in the month of August 2015 and the entire launching and completion of ROB proper is completed by February 2016. The unique features of this project, which can be summarized as: (i) LARSA 4D model, Wind tunnel test and

mathematical model for design of the cable stayed bridge

(ii) Use of precast RCC slabs to avoid scaffolding on deck

(iii) Composite structures for easier construction (iv) Monolithic Back Span (v) Durable painting by epoxy based paint of

Akzonobel (vi) LUSAS model for Construction Stage Analysis

and Geometry Control during execution. The paper deals on the above aspects elaborating the geometry control during execution using the LUSAS model to ensure safety during erection over electrified yard. This technique is going to have a big future for fast track construction of ROB over busy and bigger yards, in time to come. 2.0 General:

Bardhaman is situated at 107 km from Howrah on Howrah-Delhi route. There is an old multi span ROB of brick masonry construction with plate girders over the Bardhaman railway yard, which is connecting the G.T. Road side of Bardhaman town with Kalna-Katwa Road. The existing ROB is an extremely busy corridor carrying a large number of fast and slow moving vehicles along with pedestrian traffic. Since condition of the existing ROB is poor due to its old age, rebuilding of the existing ROB was sanctioned. A cable stayed ROB was the only option acceptable to Railways and the State Govt. in this very busy and electrified yard.

The new ROB was proposed at a distance of 65.5m towards Durgapur from the centre line of existing ROB. In order to have a clear, hindrance-free span over the Bardhaman railway yard, the proposed new ROB has cable stayed construction in a span of 188.429m (c/c). It was decided that clear distance between the northern face of the G.T. Road side abutment and southern face of the intermediate pylon will be mandatorily 120.913m. The minimum vertical clearance between the lowest point of the soffit of the superstructure and the highest rail level beneath the ROB shall be 6.50m and the maximum vertical distance between the road surface and the track will be 7.5m.

2.1 WASTAGE OF LAND MASS AT BARDDHAMAN YARD:-

The above three pictures simply indicate how the existing 2 lane ROB has occupied the important space of Barddhaman yard . Future yard remodelling and platform extension would not be possible with the present kind of system. For these reasons, a 4 lane ROB cable stayed bridge has been implemented at Barddhaman.

Recentgly in Northern Railway at Ludhiana, a Y shape ROB on one leg in curve in a busy electrical yard was constructed but that does not suffice the requirement of full use of land mass in the yard. 2.2 GEOMETRY OF THE CABLE STAY BRIDGE

AT BARDDHAMAN:

Total Length of the Bridge : 188.431 m Carriageway width : 7.5 m Number of Lanes in each Direction : 2 CP1 to P1 (Steel composite deck) : 124.163 m P1 to CP2 (RCC Deck) : 64.265 m Width of bridge deck for main span : 27.7 m Width of bridge deck for back span : 28.2 m Footpath : 1.5 m on

both sides

Cross Slope : 2 %

Structural design of the cable-stayed ROB has been carried out using LARSA-4D Software. Earlier, a wind tunnel test was also conducted to conform the simulation model made using LARSA 4D model. It may be noted that analysis of cable stayed bridge is integrally linked with the sequence of construction.

In order to execute the work of erection in very safe manner it is necessary all nodal agencies work in close coordination to ensure safety as well as fast track construction. The agencies involved are M/s Rail Vikas Nigam Limited, Kolkata PIU, as implementing agency, M/s GPT-Ranhill (JV) as the main executing agency, and M/s CES JACOBS as DDC & PMC.

On behalf of the agency, M/ STUP Consultants was involved for preparation of construction scheme, construction stage analysis and geometry control during erection, and M/s Freyssinet, France as the specialist subcontractor for stay cable supply & installation work.

3.0 CONSTRUCTION METHODOLOGY:

The scheme for erection of the main span deck and the stay cable installation was prepared considering the site constraints, safety requirements, availability of traffic and power blocks. The construction sequence is briefly summarized hereunder:

Construction of Pile foundation at common piers and at pylon location.

Setup of fabrication yard for steel and casting yard for batching plant.

(Erection of 6th panel during execution)

Construction of common pier and concrete portion of pylon.

Erection of Temporary trussles to support RCC back span.

Cast RCC back span up to common pier-2. Once concrete of back achieves full strength

steel pylons will be erected on top of RCC main beams.

12m panels for the 123m span will be brought in and will be placed and connected with already in place back span with the help of Deck Erection Crane (DEC).

1st three pair of cables will be anchored at predetermined position of girders and pylons and is to be stressed to desired level.

RCC deck slab is to be cast in the first panel. Once deck slab achieves desirable strength

subsequent panels ( up to 9th panel) will be brought in one by one and is to be positioned with the help of DEC. Corresponding set of cables will also be installed and stressed and deck slab concreting is to be done.

Last panel is to be erected spaning between 9th panel and common pier-1.

Casting of deck slab on top of already erected last panels with shear for composite action.

Second stage stressing is to be done to obtain the target deflected shape of the span.

Complete miscellaneous work e.g. crash barrier, railing, wearing course, illumination etc.

Third stage stressing is to be done to minimize bending moments.

Open to traffic. 3.1 DECK ERECTION CRANE (DEC):

A crane (DEC) has been specially designed and is built for erection of Deck steelwork. The deck steelwork comprises of three box girders – a heavier central girder and two lighter side box girders connected by cross girders at 4 m intervals. These support a cast-in-situ deck, pre-cast concrete panels are used as permanent shuttering and are placed on the box and cross girders. There are shear connectors on the cross girders and the outer boxes which provide the necessary composite action.

3.2 Equipments to be used for deck erection: a) Custom designed and built deck erection crane b) Crawler crane for feeding of materials to handle

weight of middle longitudinal girder with welded cross-girder stubs on both sides and stay cable fixtures, at the required radius.

c) Trailers and prime mover to carry material to the bridge head. The unit would be capable of turning in a short radius to accommodate constraints at site.

d) 3 nos. trolleys and associated track for feeding of fabricated girders, precast slabs, etc. to the erection front.

e) Joint bolts (HSFG) checked for size and quality, and sorted and kept ready size-wise for use in the joints.

f) Small tools and tackles, slings, etc. as per site requirements.

3.3.Few sketches are shown for better appreciation:

4.0 Construction Stage Analysis

This paper also briefs about the Construction Stage Analysis and Geometry Control of cable stayed bridge at Bardhaman. Section properties, material properties, loadings at different stages and other considerations assumed for analysis are mentioned in

(Sectional view)

(Plan of DEC)

(Erection of initial panels)

detail. These are referred from the various working drawings fabrication drawings and data provided by the contractor and DDC. Methodology for the analysis and geometry control is also described. The results obtained are presented along with the actual site results.

4.1 NECESSITY OF CONSTRUCTION STAGE ANALYSIS & GEOMETRY CONTROL:

In case of stay cable bridges, it is observed that member stresses and deflections during erection stage are often governing, and exceed the service stage loads. Hence, it is important to ensure that the stresses & deflections are within safe limits, as per the scheme of construction being adopted. Moreover, as the work is being executed over busy & electrified yard with minimum specified clearances, it is to be ensured that the deflections do not exceed the boundary conditions. Hence, the contractor submitted a Construction Stage Analysis (CSA) to ensure that the erection stage loads were within safe limits. At every stage during erection, the actual observed deflections were measured to validate the CSA results and/or correct the geometry to within the boundary conditions. 4.2 MODELLING CONSIDERATIONS:

Geometry of deck and pylon is modelled using beam elements in LUSAS. Deck is modelled as grillage of longitudinal and transverse members. Longitudinally deck is modelled as three main beams representing deck slab. Transverse beams are modeled with steel composite properties. For modelling solid deck part of anchor span, slab is divided into no of beams. Spacing of beams in longitudinal and transverse direction is kept to maintain the ratio of spacing near to unity. Main beams are modelled as separate entity. Spacing of transverse beams for the main

span is kept same as that of the cross girders of each panel. Accordingly contribution of the deck slab is considered for working out the properties. At pylon location and at the end of anchor span, deck is integrated with substructure. So the substructure is also modelled as part of grillage. The wall is divided in to longitudinal (vertical) and transverse members. The pile cap is also modelled along with spring supports with the stiffness mentioned in original design report. Pylon is modelled with line elements along the centerline of members viz. pylon legs, cross ties, and anchor points in pylon head. Cables are connected to pylon at height of their intersection with the centre line of pylon seen in longitudinal elevation. Cables are modelled as bar elements between pylon and deck without sag. Cables are connected to longitudinal beams of deck at their point of intersection with beam centerline. Cross beams are positioned at each intersection points. Effect of sag was worked out separately and accounted in the overall analysis by superimposition. Alternatively sag of cables can be incorporated using beam elements for modelling the cables. Longitudinal vertical profile of the deck is precisely followed while modeling the deck. Also the vertical position of the longitudinal elements (relative to each other in transverse direction) is modelled such that the transverse slope of deck is precisely modelled. 4.3 MATERIAL PROPERTIES:

4.3.1 Concrete:

The widely accepted CEB-FIP Model 1990, which is used to represent the concrete properties with age effect is used. Variable Creep and shrinkage effects are considered in this model. The Compressive Strength of concrete varies with time is represented as - fcm(t) = fcm exp(s(1-(28/t)^0.5)) s = 0.25 (For normal cement concrete) Concrete strength required is 50MPa (cube) = 40 MPa (cylindrical) Ec = 2.15E4 x (fcm/10)(1/3) = 34129000 kN/m2. Other concrete properties: Poison ratio = 0.15 Comp. strength = 40000 kN/m2. Density = 2.548 t/m3

Relative humidity = 70% Coefficient of thermal expansion = 0.000012

LUSAS Model of Bridge

Nominal size = 2Ac/U Steel properties: Young’s modulus = 200 E+6 kN/m2. Density = 7.85 t/m3. Poison ratio = 0.3 Coefficient of thermal expansion= 0.000012 4.4 SUPPORT CONDITION: At pier CP1, pin support is assumed at bearing level. So only vertical and transverse translations are restrained and other displacements are allowed to be free. Pylon P1 and Pier CP2 are modelled as pilecap with spring supports of stiffness as mentioned in design report. Temporary supports with their corresponding stiffnesses are assigned to rear concrete deck. These supports are modelled as "Compression only" spring supports and will be ineffective when the deck lifts off. The stiffnesses of these supports are calculated according to the drawings.

4.5 LOADING: Self weight of decks is applied as body force to longitudinal members, and the weight of cross girder is applied as UDL on corresponding member. The weight of steel stiffeners, diaphragms (as mentioned in detailed fabrication drawings) are precisely considered and their respective loading locations are shown below. To account the weight of evenly distributed stiffeners/studs, material density is modified appropriately. 4.6 DL considerations for central girder (MG2): The following table and figure shows a typical 12m segment of main girder along with the DL considered.

DL considerations (MG2)

4.7 DL considerations for side girders (MG1): The following table and figure shows a typical 12m segment of main girder along with the DL considered.

DL considerations (MG1)

4.8 DL considerations for Pylon: The weights of pylon segments are also considered according to the detail drawings by appropriately modifying material density.

DL considerations (Pylon)

SN Pylon

Total WT

Consideration for

Refer

(kN) Model Dwg. No.

1 PL1 3115 Density

Modified to 13.23 T/m3

9419/E/DD-101, 108,

131 to 134

2 PL2 5070 Density

Modified to 13.34 T/m3

9419/E/DD-102, 135 to

138

4.9 DL considerations for Deck Erection Crane (DEC): The self weight of DEC considered for analysis is applied as four point loads. To account for the weight of rails etc., the weight of DEC has been increased accordingly (7.6% for front and rear support and 25.4 % for CW trolley). Hence the total weight of DEC considered is 1806 kN. The position of DEC at the time of panel erection is as shown in the Drawing No. 9419/E/DD-006. For ease in casting of deck, the DEC is considered to move backwards by 8m from its previous position.

(DL consideration for DEC)

4.10 DL considerations for Cable Installation Equipments and Material trolley rails. To account for the weight of cable installation equipments, 1tonne load is considered at each splice point location of main girders. (Refer Freyssinet 1309-NTA-002-Rev.D). For each of the six material trolley rails, 1kN/m load is assumed. 4.11 SIDL considerations:

SIDL considerations are referred from the CES design report. – For crash barrier: 1.946 kN/m2 (Applied to total

width of 25.7 m) – For wearing coat: 1.43 kN/m2 (Applied to total

carriageway width)

4.12 PANEL ERECTION TIME CYCLE AND CONSTRUCTION STAGES:

The typical 27 days time cycle for complete erection of a panel is as given below.

SN Action Day 1. Erection of MG2 1 2. Erection of MG1 1 3. Erection of 6 nos. cross girder 3 4. Fixing of working platform, safety net

and installation & stressing of cable 3

5. Erection of precast panels 2 6. Fixing of reinforcement, side

formwork and concreting 3

7. Deck Slab Curing, Cable Installation & Stressing of Backspan for next Panel, Moving of DEC and other preparatory works

14

Total 27

Construction sequence for the whole process is precisely considered in the analysis. Nomenclatures of cables are at Annexure-I. The stages are mentioned below.

For better appreciation, please refer to Annexure-II.

5.0 METHODOLOGY FOR GEOMETRY CONTROL:

The main aim of the Geometry Control is to ensure that the proper clearances from OHE are available at all times during the construction activities, and member stresses are within safe limits. Upon completion of the construction and prior to opening to traffic, the structure should achieve the required geometry of the bridge deck as per approved drawings. There are two ways to achieve the required geometry, viz. 1) by adjusting the stay cable forces and 2) by providing pre-camber to the bridge deck. In many bridges, combinations of the two methods are adopted, but in the present case of Bardhaman, the geometry control is exercised through adjusting the cable forces. Cable forces for the each panel are adjusted such that the upward deflection of the panel due to stressing of corresponding cable will counteract the net total downward deflections due to erection of subsequent panels and due to laying of SIDL. 5.1 SURVEY & MONITORING OF STRUCTURE Prior to commencement of the erection and stay cable activity, the results of the Construction Stage Analysis, i.e. expected deflections and related cable forces at each stage are presented in tabular form in the drawings. For each panel, the deflections are given for the following stages.

After stressing of back span cable After movement of Deck Erection Crane

(DEC) After erection of steel panel After stressing of main span cable After concreting of the main span unit.

To ascertain the behavior of structure, it is very necessary to monitor the structure at site. In each panel cycle, deck and pylon shall be surveyed at following stages:

i) After stressing of back span cables ii) After movement of DEC to next position (Only front panel two points of each MGs) iii) After erection of steel panel iv) After stressing of main span cables v) One day after casting of slab

Panel tip point and anchor point for all the erected panels are monitored along with top of pylon legs and

5th cable anchor point of the pylon legs at the end of each of the above stages. Levels taken jointly by Contractor, PMC and Employer at each stage are sent to the Geometry Control Expert (Viz. STUP) for analysis at each stage and comparison with predicted values, and for proposing adjustments in cable stay forces, in case required. 6.0 CORRECTIVE MEASURES: After each stage, the survey report for deck and pylon deflections along with comparative statement shall be prepared by STUP and sent to DDC. After studying the difference in the deck RLs and pylon deflections, any deviations from the expected values, the corrective measures as proposed by the GC Expert.

The pylon deflections can be corrected effectively with back span cable stressing.

The geometry control of the deck can be done with front cable forces

Cable re-stressing is also proposed if required.

For any proposal, the stress checks for all main girders, pylon and cables are performed. After approval from the DDC, further construction is allowed. Generally, it is proposed that re-stressing shall be done only in cases where the deflection of the deck is varying significantly beyond the estimated/required value. However, a global check shall be carried out after completion of fifth panel i.e. after completion of half the length of main span. Re-stressing will be done if required after reviewing the site data after completion of fifth panel. In this connection sample details of monitoring the levels/sway of pylon, girder are at Annexure-III, IV, V. 7.0 SAFETY PRECAUTIONS: For safety during the erection activity, power blocks of overhead traction line are absolutely necessary and should be arranged during all stages of the deck erection system. Fool-proof communication arrangements should be set up and understood by all concerned. A complete safety document has been prepared and regular drills are conducted. Some of the key safety measures adopted are as follows:

Design of DEC was vetted and approved by third party.

All mechanical equipment including DEC are designed for 25% additional incidental load to provide adequate safety margin.

DEC and other cranes to be used in this work are regularly tested and certified by third party experts.

During erection of main box the erection crane (DEC) to be suitably jammed.

Arrangement of handrails and well designed working platforms for all working points.

All workers to be provided with fall prevention ropes connected to a lifeline at all times.

Safety nets to be used when carrying out the deck steelwork erection.

Sizing of lifting rope shall be carried out as per relevant IS code with factor of safety of 5 on working load.

Sizing of drives for winches shall have a margin of 25% with mechanical & electrical safety interlocking arrangement.

All drives shall be reversible type to allow rotation in the both direction for lifting & lowering.

All brakes shall be fail safe type. Power shutdown to be ensured before each

operation. Proper communication system to be

established for coordination during the process of erection.

Strict control of access of outsiders into site to prevent unauthorized persons entering the site.

Inculcating a culture of safety and zero accidents at the worksite

8.0 Other Salient Features: 8.1 Selection of pylon and erection at site

Height of the pylon is dictated by the stability analysis and economics of the bridge. A tall pylon will minimize the compression introduced into the steel deck system, but may increase the length of cable used while a short pylon will introduce undesirable compressive forces into the steel deck structure.

The cross section is sized for not only strength and deflection requirements, but

also to accommodate a stressing and inspection route.

Height of the phylon above deck has been fixed as 54.768 m. Three steel pylon towers (2.5 mx2.0 m box) connected by with ties and founded on RCC wall of M50 grade (concrete part of pylon).

8.2 Aerodynamic test (wind tunnel test)

Based on the preliminary Aerodynamic Studies as stated in Para I Report submitted by CRRI, the bridge is not susceptible to classical flutter and galloping. Buffeting, Vortex induced Oscillation – Limited Amplitude Oscillation. The Amplitude of vortex induced Oscillation is very low and not likely to cause discomfort to users using Frequency Domain Approach, peak buffeting response was estimated as 0.160 m for assumed aerodynamic force coefficients terrain roughness (plain terrain, surface roughness parameter = 0.005 m) To obtain the steady state force coefficients for bridge deck (drag, lift and moment coefficient) Repeat the buffeting analysis (if required) Model Design and details of sectional model Model scale: 1:40 and blockage is about 5.9% Length of model: 1440mm long Width of model: 692.5 mm Aspect ratio (length of width ratio): 2.08 8.3 Strands and Stressing For the stay cable work, Freyssinet’s Parallel Strand System (PSS) stay cables have been adopted, which has a design life of 100 years and is the most advanced and durable stay cable system in the world today. There are 3 planes of stay cables with 18 cables each. Vibration control dampers are being installed in long stay cables (> 80m) as per CIP recommendations. Sensors for permanent monitoring of deflections and stresses

(Safety drills at Site)

(Pylon being erected by Tower Crane)

during service condition, are also being installaed in 6 stays subjected to heavy loads. A maintenance manual for the stay cables during service has been prepared in consultation with M/s. Freyssinet to ensure long term maintenance during service 8.4 Painting scheme In order to ensure maintenance-free construction, a scheme of painting of the structural steel pylons and deck has been adopted with a design life of 40 years. The scheme for painting from M/s AkzoNobel is as follows: Copper Slag Blasting of the fabricated

component to SA 2.5 with surface profile of 50-75 micron in accordance with ISO specification

Apply Primer (Interzinc 52) to 75 Micron DFT Apply Intermediate Coat (High Build Epoxy MIO

Intergard 475HS) to125 Micron DFT. Apply Top Coat (Polysiloxan, Interfine 878) in 2

coats totaling to 120 Micron DFT. 8.5 Sequencing and compliance to checklist For a project like this sequencing of various activities are very important. Prior to undertaking any new activity, the methodology and checklist is prepared and trials are conducted if necessary. All the activities and operation are to be undertaken as per the method statements and checklists. All such activities listed in checklists are required to be checked before undertaking such operations. 8.6 Use of precast slab Precast slabs were made at casting yard and subsequently placed on composite girders to become integral part of the composite structure. By adopting the precast slabs, use of formwork and scaffolding, which is time consuming and unsafe for working in close vicinity to electrified tracks, could be avoided. Special care has been taken to get the best quality finish. 8.7 Trial of girders by deck erection cranes In order to have 100% surety and safe execution over the yard, the trials were made for girders by deck erection cranes to ensure the confidence of the entire

team. The trials were also helpful in understanding the time required for each activity and for requisition of traffic and power blocks to the traffic department of Railways.

8.8 Execution by taking power and traffic blocks There are total 10 Nos. of panels and the cables are connected in 9 Nos. of stage panels. During erection of the main girder and cross girder suitable traffic and power blocks were planned and till 30.11.2015, 5 Nos. of panels have been erected and erection of 6th panel has been planned in 1st week of December’15.

(Night works) The details about the block can be seen at Annexure-VI. 9.0 Future model for implementation over busy yard: Cable stayed bridge construction is very common worldwide whereas in India there are few such bridges. The main reason for less construction is due to absence of technology, economics and people tend to continue with the existing practices of construction. The oldest attempt of a cable stayed bridge dates back to 1784, when a German carpenter, C.T.Loescher, designed a structure entirely in timber.

9.1 Composite Cable Stayed Bridge: Although composite stay cable bridges are very rare worldwide, it was adopted at Bardhaman to have faster erection over the yard as well as to ensure more predictable geometry during construction. Composite cable stayed bridges are very rare. One such bridge has been constructed during mid-1980s as the existing tunnel underneath the Houston Ship channel in

Texas, USA could not cope with the existing volume of traffic and had to be replaced by a bridge. The said bridge is across 132 Km is at Hudson between the city Bay Town and LaPorte.

9.2 Because of the large beam width required for 4 lanes at Barddhaman, 3 cable planes were proposed. Entire structure over 124.88 m are having 12 Nos. of panels and average length is 12 m. The erection technique was with the help of deck erection crane specially designed for erection of main girder and cross girders and DEC is also being used for placement of precast slabs. The details of deck erection crane have been deliberated in previous paras. For fabrication of steel girders i.e. main girder and the end girder and also pylon segments, a separate fabrication yard having area of about 4 hectare was made and the entire fabrication yard was independent to have proper quality control. 9.3 Traffic and Power Blocks of Short Duration during the erection activity :- The requirement of traffic block and power block were worked out and these blocks were taken only where the OHE was just under the erection and for tightening of HSFG bolts. As explained in previous paras, 27 days cycle was made for erection of one such panel which included erection of 1 central girder, 2 end girders, 6 Nos. of cross girders, placement of precast slabs, concreting over the deck and in between placement and stressing of cables by Freyssinet. The first traffic cum power blocks was taken on 16.08.2015 and the construction over the bridge was completed in February, 2016. Since this kind of structure was being constructed for the first time and there were many infringements i.e. office, quarters, Union office, various utilities, it took more time in finalization of design and drawings and shifting of utilities. 9.4 There are a large number of bridges over busy yard such as Chandmari and Benaras bridge in the approach of Howrah yard and they were sanctioned for more than 6 years back. The technique used for the Barddhaman ROB is likely to be very helpful for implementation at site. The planning of fabrication and casting yard is done

elsewhere and all such activities at casting yard and fabrication yard can be done with proper quality and only erection can be planned over the yard with cable stayed bridge technique. Any bridge which is required to be constructed over busy and long yard are to be planned with cable stayed bridge so that the work can be executed without any interference in the yard. Such technique avoids construction of piers inside the yard which in turn do not become bottlenecks for yard remodeling in time to come. Construction inside the yard is also difficult and from the workability point of view and for safer and easier construction, the cable stayed bridge serves the purpose. Further, any major derailment may cause damage to the pylon/pier or structures. In case of cable stayed bridge, this can be avoided. It is felt that such construction of cable stayed bridge over very busy yard has got the solution to the existing problems and will solve the problems of construction of ROBs over the very busy yard in time to come. 10.0 Co-ordination and teamwork:- For a project of this type and of this magnitude a lot of co-ordination works are required. Co-ordination is required to be made with differing nodal agencies e.g. State Govt. for utilities and approaches, Railways for approval at various levels and for traffic/power blocks. There are various agencies involved for implementation e.g. GPT-Ranhill (JV) - the executing agency, Stup Consultant – the designer on behalf of agency, CES-Jacob – the designer on behalf of RVNL, PMC, IIT Roorkee – the proof consultant, CSIR etc. Therefore a complete team work is needed for successful implementation. 11.0 Appreciation: 11.1 On successful completion of the work,

Commissioner of Railway Safety after his inspection on 29.02.2016 recorded –

“Overall, the construction work is being exdecuted in a professional and competent manner, with high degree of quality control, safety measures and detailed micro-planning of all activities. Prior to undertaking any key activity, detailed method statement is planned and trial runs are carried out. A good quality work with a very meticulous planning has been done and it is really praiseworthy to find

that the traffic and power blocks planned have been sanctioned, availed and cancelled in time.”

11.2 COM/Eastern Railway recorded – “I wish to put on record that the entire work was executed with precision and all blocks were cancelled either before or on time.

Shri Rajesh Prasad, CPM(M)/RVNL and his team deserve compliments for the meticulous planning and precise execution of the entire work. “ 11.3 CBE/Eastern Railway recorded – “Due to the meticulous planning, the erection over the yard and platforms has now been completed.

I would like to compliment the efforts made by RVNL team, led by Shri Rajesh Prasad, CPM(M)/RVNL for this project.” 11.4 DRM/Howrah/Eastern Railway recorded – “From the Division’s point of view, the fact that traffic & power blocks were adhered to strictly, made it a pleasure working with a thoroughly professional team led by Shri Rajesh Prasad.

In my view this deserves to be a case study on project planning and execution so that Indian Railways and other project executing organizations can learn and replicate the best practices.” 11.5 Dr. Prem Krishna, Ex. Professor, IIT/Roorkee recorded: “Some of the special features which I have noted particularly and appreciate are LASA 4D model for design of the cable stayed bridge, wind tunnel test, concept of precast slab to avoid scaffolding, composite structures for easier construction, monolithic back span, durable painting by epoxy based paint of Akzonobel and LUSAS model for geometric control during execution.

I must complement the way the project has been conceived and is being implemented by your team at site headed by Sri Rajesh Prasad, CPM(M), Kolkata. The team should continue with the same kind of zeal and passion in future”

11.6 Mr. R R Jaruhar, former ME, Railway Board recorded- “Likewise in Barddhaman bridge, the innovative skills and planning have been superb. For this, Shri Rajesh Prasad, CPM has been justly in the forefront. I have found him to be good learner. His dynamism is infectious. He is superbly backed by the CES – the PMC and GPT the main contractor. They have put up superb team effort which we must acknowledge and compliment. The Eastern Railway team deserves kudos for their excellent support.”

(After Completion over yard)

12.0 Conclusion In India constructions of cable stayed bridge are far less than the construction of such bridges in other countries. The concept and technical know how in India is relatively new but after execution over busy yard like Nagpur, Barddhaman, the construction of cable stayed bridges is going to play important role in time to come. The execution scheme and geometric control followed for Barddhaman bridge have already been explained in various paras and the bridge has been succesfully completed. Any ROB over busy yard can be planned with cable stayed bridge and a very precise method of geometry control can be adopted. Such construction in future could be on very fast track based on the model developed at Barddhaman. This technique will ensure proper use of land mass of yard for future yard remodelling and passenger amenity works.

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Annexure‐I

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1 Casting of RCC wall at P1 and CP2 is considered to be complete.

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2 Casting of RCC beam & slab between P1 and CP1.(DL is assigned. )

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3 Erection of steel pylon. (Gravity is assigned to erected pylon )

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4 Activation and stressing of Backspan cables 6010 & 7010

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5 Erection of 1st panel.

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6 Activation and stressing of cables 6009, 7009.

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7 Panel 1 Green Concrete Load and DEC moved backwards by 8m.

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8 Activation of Deck on 1st panel.

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9 Erection of DEC.

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11 DEC moved for 2nd panel.

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12 Erection of 2nd panel.

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15 Activation of Deck on 2nd panel.

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17 Restressing of 5008

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18 DEC moved for 3rd panel.

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19 Erection of 3rd panel.

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22 Activation of Deck on 3rd panel.

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Load 24 DEC moved for 4th panel.

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25 Erection of 4th panel.

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28 Activation of Deck on 4th panel.

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30 DEC moved for 5th panel.

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Annexure‐II

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Load 59 DEC moved for 10th panel.

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63 Remove DEC

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64 Crash Barrier load is applied.

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65 Second Stage Stressing

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66 Temporary backspan supports removed

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67 Wearing Coat load is applied.

Annexure‐III

Annexure‐IV

Annexure‐V

Annexure‐VI

Innovative solution for crossing larger spaces like railway yard

Engineering

Transcript of Innovative solution for crossing larger spaces like railway yard