problems in Maintenance of Railway tracks in deserts And Possible solutions By Anurag sharma Former chief engineer Indian Railway

Transcription

1 problems in Maintenance of Railway tracks in deserts And Possible solutions By Anurag sharma Former chief engineer Indian Railway

2 Tracks on Indian Railway North western Railways in India has large stretches of track in the Thar desert on its two divisions Division Total track km Track in desert % of total track Area of sandy soil Jodhpur division 1805 km 770 km 40% sq km Bikaner division 2241km 479 km 38% Sq km

3 Desert in India

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5 LOCATION SHOWING SANDY TERRAIN JSM BME

6 TYPES OF SAND DUNES ON THAR DESERT

7 CLIMATIC CONDITIONS OF DESERT REGION Max. Wind velocity in Summer 70 to 80 kmph Average Mean Wind velocity 30 to 40 kmph Direction of Flow from south-west to north-east Annual Rainfall 100 to 300 mm But in particular area less than 100 mm or even no drop of rain in particular year. Temperature Season Ambient Sandy Soil at Surface Sandy Soil at 50 cm below Summer Max. up to 50 0 C 55 0 to 60 0 C 35 0 C Winter Min. up to 0 0

8 PROPERTY OF SAND (General) The properties of the Dunes Sand are as follows Non 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.

9 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.

10 Track structure in desert region Gauge Rails Sleepers Ballast cushion Fittings BG 52 kg /m LWR Concrete sleepers in M=7 density 250 to 300 mm stone ballast cushion Elastic fastenings MG Mostly 90R or 75R and 60R in some case. It is mostly SWP CST-9 and ST sleepers with wooden sleepers on the joints 200 mm ballast cushion in most of the cases but sand cushion at some Conventional fittings places

11 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.

12 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 sand i) Deep screening and overhauling of the track is not effective.

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14 Chemical composition of the sand in Rajasthan desert area

15 Engineering properties of the sand in the Thar desert.

16 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.

17 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.

18 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.

19 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.

20 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.

21 TYPES OF SAND DUNES

22 HALF MOON TYPE DUNE

23 HALF MOON TYPE DUNES

24 Compound Parabolic Dunes

25 TRANSVERSE DUNES LINEAR DUNES

26 Mechanism of sand storm As 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.

27 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.

28 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.

29 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 obstructions If 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.

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37 Problems due to sandy storms and cyclonic rains Blockade of railway track due to sand deposits Loss of elasticity of track due to chocking of ballast bed Drainage problem Corrosion of rails and fittings Loss of visibility due to new sand dunes Excessive wear of rails Breaches even in scanty rain fall Signal failures

38 Problems faced during sand storms and cyclonic rains Please look at some panoramic views of track after sand storms and breaches

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

40 OTHER PROBLEMS FACED (Contd.) Effects on Yard Drainage etc.

41 OTHER PROBLEMS FACED (Contd.) Effect on Visibility

42 OTHER PROBLEMS FACED (Contd.) Effect on Visibility

43 Day to day remedial actions Some of the photographs showing common remedial measures in the desert region are shown in coming slides

44 ROUTINE MAINTENANCE WORKING (During Sand Storms) (Contd.) Deputation of patrolman

45 ROUTINE MAINTENANCE WORKING (During Sand Storms) (Contd.) Removal of sand by Tractors

46 ROUTINE MAINTENANCE WORKING (During Sand Storms) (Contd.) Flange way clearing by manual labour

47 ROUTINE MAINTENANCE WORKING (During Sand Storms) (Contd.) Removal of Sand by manual labour

48 Precautions to be taken in case of a new line Route the railway line around the high dunes Select the formation on embankment if the prevailing wind blows along the line and in the cutting if the wind blows across the line In high velocity wind and sandy region select the height of the bank equal to the average height of the dunes

49 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.

50 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 embankment Erosion 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.

51 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.

52 Problems and possible solutions contd. During monsoon sandy cuttings or soft moorum move along with water Widen the cutting ease out the slopes Pave the side drains with stones. In such areas patrolling is necessary

53 Problems and possible solutions contd. Huge sand deposits take place on the embankment and in the cuttings leveling of adjoining sand dunes Spraying of oil on the sand dunes to stabilize them Dress up ridges by the side of track Provide air passage between the sleepers and the rails Cut 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.

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

56 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 land Dig trenches parallel to railway line on the boundary on wind ward side

57 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.

58 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.

59 Solutions to drift sand contd. Provide shelter belt of trees shrubs and grass in rows. Tallest tree should be in the centre

60 REMEDIAL MEASURES (Contd.) 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

61 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.

62 Other Happenings in the Area After the commissioning of Rajasthan canal problem sand blowing have come down substantially in its command area Plantation in the area in general has reduced the problem.

63 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.

64 Conclusions After the strengthening of the track structure during gauge conversion problems have been reduced Easing out of grades has also helped Use of stone ballast in place of sand ballast track levels are better maintained Plantation has helped in sand dune stabilization