problems in Maintenance of

Railway tracks in deserts

AndPossible solutions

ByAnurag sharma

Former chief engineer Indian Railway

Tracks on Indian Railway North western Railways in India has large

stretches of track in the Thar desert on its two divisions

54737 Sq km

81142 sq km

Area of sandy soil

38%479 km2241kmBikaner division

40%770 km1805 kmJodhpur division

% of total trackTrack in desertTotal track kmDivision

Desert in India

BME

JSM

LOCATION SHOWING SANDY TERRAIN

TYPES OF SAND DUNES ON THAR DESERTTYPES OF SAND DUNES ON THAR DESERTTYPES OF SAND DUNES ON THAR DESERTTYPES OF SAND DUNES ON THAR DESERT

CLIMATIC CONDITIONS OF DESERT REGION

Max. Wind velocity in Summer – 70 to 80 kmph

Average Mean Wind velocity – 30 to 40 kmphDirection of Flow – from south-west to north-east

Annual Rainfall – 100 to 300 mmBut in particular area less than 100 mm or even no drop of rain in particular year.

Temperature

Min. up to 00Winter

350C550 to 600CMax. up to 500CSummer

Sandy Soil at 50 cm below

Sandy Soil at SurfaceAmbientSeason

PROPERTY OF SAND (General)

The properties of the Dunes Sand are as followsNon Cohesive.Sand Dunes without any type of vegetation.Highly errodable due to wind.(Even sand dunes of about 10 mtr. Height can shift their position in one Year)Very difficult to ply any vehicle except tractors and dozers.Get very hot during day and cold in night.

INDIA RAILWAYS SERVICES IN DESERT In India tracks of North western Railway zone tracks are located in the desert.These tracks were laid as per meter gauge standards to serve the local population but in the last 15 Years most of the lines have been converted into Broad gauge on which long distance trains and heavy good traffic also run. This has increased the importance of this network.In Bikaner division there are problems of sand drift while on Jodhpur division there is problem of cyclonic rains.

Track structure in desert region

Conventional fittings

200 mm ballast cushion in most of the cases but sand cushion at some

places

CST-9 and ST sleepers with wooden sleepers on the joints

Mostly 90R or 75R and 60R in

some case. It is mostly SWP

MG

Elastic fastenings

250 to 300 mm stone ballast cushion

Concrete sleepers in M=7 density

52 kg /m LWRBG

FittingsBallast cushion

SleepersRailsGauge

TRACK MAINTENANCE IN DESERT REGION

On Indian Railways regular maintenance is now being done with the help of track machines like tie tampers and ballast cleaning machines, etc. Due to mechanization hardships faced by Railway men in old days have minimized. But some of the problems persist.

Indian Railways are making continuous efforts to improve the reliability and safety of services.

Special maintenance Problems in desert areas a). Extreme Temperature variations.b). Lack of Vegetation or poor vegetation.c). Scanty rainfall, active shortage of the water for

the gang men and other staff in field.d). Corrosion due to salinity in the soil and water.e). Insufficient water-ways.f). Disruption due to sand storms.g). Water breaches due to obstructions in water

ways.h) Disturbance of longitudinal levels due bulking of

sandi) Deep screening and overhauling of the track is not

effective.

Chemical composition of the sand in Rajasthan desert area

Engineering properties of the sand in the Thardesert.

Types of Sand dunes

•Old system type Average height of 20m to 40m – They are stable •New system type up to a height of 2m to 8m –they are unstable and they move.

Types of dunes on the basis of shapes

Barchans dunes: The barchans are formed from a relatively small sand supply under the influence of moderate wind of constant direction, thus stand apart from each other – their convex side heading into the wind and the tips of their crescents tapering off to leeward.

Star dunes: A cluster of Barchans forms star dunes. These dunes are formed when wind blows from all directions. Unlike other types of dunes, which move in the direction of prevailing wind, star dunes remain stationary.

Transverse dunes: these are product of moderate, one way winds which move light sand, tumbling air eddies swirl heavier grains to the side which make ridges.

•Longitudinal dunes: these dunes are formed when stronger one way wind moves, both fine and coarse, sand particles cutting the long troughs parallel with the path of the wind.

TYPES OF SAND DUNES

HALF MOON TYPE DUNE

HALF MOON TYPE DUNES

Compound Parabolic Dunes

TRANSVERSE DUNES LINEAR DUNES

Mechanism of sand stormAs soon as the wind velocity is more than 16Kmph at one meter above ground sand starts lifting off the ground.Sand transportation is directly proportionate to cube of the velocity of the wind.During storms transportation of sand particle takes place as under:Rolling or surface creep- bigger sand particle(>0.25mm) move along the surface.Saltation- Medium size particles(0.15 to 0.25 mm) move constantly rise and fall and move by leaping. Suspension –Fine sand Particles(< 0.15mm) are carried away to large distances.

DEPOSITION OF DRIFT SAND AROUND OBSTACLES

Pattern deposition of drift sand varies depending upon the flexibility, permeability and location of the obstruction. Study of these patterns of deposition help in deciding the plantation strategy.

Behavior of Sandy Soil/Sand Dunes during Sand Streams. (Contd.)

• During sandy storm – sand flows with wind in three layers.

– First layer of heavy particle at lower height.– Second layer of particle with dancing (sine wave). Movement up to 2

mtr. Ht . Which is main cause of deposition of sand.– Third layer of suspended particle above 2 – 4 mtr. Ht.

Aerodynamic Characteristics of Sand Blowing

Through porous obstruction Velocity of wind gets reduced due to porous barrier and upto 20 H line of length the effect of sand blowing is less.

Through impervious obstructionsIf velocity of wind is restricted by dense barriers the wind flows in turbulent pattern and eddy currents forms which results in deposition of sand near barriers.

Problems due to sandy storms and cyclonic rains

Blockade of railway track due to sand depositsLoss of elasticity of track due to chocking of ballast bed Drainage problemCorrosion of rails and fittingsLoss of visibility due to new sand dunesExcessive wear of rails Breaches even in scanty rain fallSignal failures

Problems faced during sand storms and cyclonic rains

Please look at some panoramic views of track after sand storms and breaches

•WATER BREACHES IN RKB-JSM SECTION ON 20/8/2006

OTHER PROBLEMS FACED (Contd.)

•Effects on Yard Drainage etc.

OTHER PROBLEMS FACED (Contd.)

•Effect on Visibility

OTHER PROBLEMS FACED (Contd.)

•Effect on Visibility

Day to day remedial actions

Some of the photographs showing common remedial measures in the desert region are shown in coming slides

•Deputation of patrolman

ROUTINE MAINTENANCE WORKING(During Sand Storms) (Contd.)

ROUTINE MAINTENANCE WORKING(During Sand Storms) (Contd.)

•Removal of sand by Tractors

ROUTINE MAINTENANCE WORKING(During Sand Storms) (Contd.)

•Flange way clearing by manual labour

ROUTINE MAINTENANCE WORKING(During Sand Storms) (Contd.)

•Removal of Sand by manual labour

Precautions to be taken in case of a new line

Route the railway line around the high dunesSelect the formation on embankment if the prevailing wind blows along the line and in the cutting if the wind blows across the lineIn high velocity wind and sandy region select the height of the bank equal to the average height of the dunes

Precautions to be taken in case of a new line contd.

Increase the width of right of way for protective measures. At least 100 m land width on either side of the track should be available.Carry out erection of shields protecting the vegetation on the strip adjacent to formation.Adopt mild slopes not steeper than 1 in 200 .Make effective catch water drains to minimize the damage during the cyclonic rains.

Problems in the existing lines and possible solutions

Erosion of the bank during summer months

Where railway alignment is across the direction of wind this damage is more. Provide shield of local bushes in slopes and edge of embankmentErosion of the bank during monsoon

Make cross drains one per rail length as a pre-monsoon work . Dress up slopes away from the centre of track.. At the moth of the drain provide dry bushes and do paving of the drain.

Problems and possible solutions contd.

Loose sand from the top of the bankroll down to the formation due to strong wind or due to vibration

Widen the cuttings. If possible ease out the slopes and turf the slopes with the arid bushes.

During monsoon sandy cuttings or soft moorum move along with waterWiden the cutting ease out the slopesPave the side drains with stones.In such areas patrolling is necessary

Problems and possible solutions contd.

Problems and possible solutions contd.

Huge sand deposits take place on the embankment and in the cuttingsleveling of adjoining sand dunesSpraying of oil on the sand dunes to

stabilize themDress up ridges by the side of trackProvide air passage between the sleepers and the railsCut sand channels in the direction of wind on both side of track. Trapezoidal channels with wooden sleepers on the mouth of the channel increase their effectiveness.

Solutions to drift sand contd.Provide impervious wall 6” above and 18” below ground on the dune on the wind ward side

Solutions to drift sand contd.

Remove obstacles from the leeward side. There should be no obstacles higher than the formation level.Plantation/ protection of small plants in railway landDig trenches parallel to railway line on the boundary on wind ward side

Solutions to drift sand contd.

Stabilize the sand dunes by plantation with the help of a special bricks which retain moisture even up to one year.

Solutions to drift sand contd.Protect the sand surface with a cover spray with emulsion of petroleum resins.Roughening of the surface for slowing down the wind velocity. For this barriers are placed 10m from the track. Also trenches are dug on the leeward side to collect the sand. Av series of banks and trenches helps in controlling the problem for the longer duration.

Solutions to drift sand contd.

Provide shelter belt of trees shrubs and grass in rows . Tallest tree should be in the centre

Local Shrub of 1 ft. height

Local Shrub of 1 ft. height

15 M 10 M

Local green plant of 2 ft. height

Track

Plantation in pyramid shape

REMEDIAL MEASURES (Contd.)

Changes during the gauge conversion

After the gauge conversion of the sections in the desert area, problems have come down due to following improvements done during gauge conversion project:

1. Use of stone ballast in place of sand and kankar ballast.

2. Easing out of the slopes.

3. Heavier track structure i.e. rail and sleepers.

Other Happenings in the Area

After the commissioning of Rajasthan canal problem sand blowing have come down substantially in its command areaPlantation in the area in general has reduced the problem.

Magnitude of the Problem at present

Due to the above reasons and other measures taken by the Indian railways, no of accidents and blockades to the traffic have been reduced to 1 or two in year and the blockade of traffic on an average of 7 days in a year.

Due to vigilant management most of the accident causing occasions get converted into cancellation of trains or loss of punctuality cases.

Conclusions

After the strengthening of the track structure during gauge conversion problems have been reducedEasing out of grades has also helpedUse of stone ballast in place of sand ballast track levels are better maintainedPlantation has helped in sand dune stabilization