1. Introduction to Railway engg..pptx

Railway engineering is a multi-faceted engineering discipline dealing with the design, construction and operation of all types of rail transport systems.

1. Introduction to Railway engineering Prepared By : Prof. Mayuri J. Patel Assistant Professor Civil Engg. Dept, DGGEC, Surat.

2. A Permanent Way Railway Track is also known as Permanent Way . A permanent way is the combination of rails, sleepers, ballasts, fixtures and fastenings , etc . The purpose of use of a permanent way is to provide the permanent facility for safety and quick movement of normal commercial traffic between the starting and destination stations. Permanent way costs nearly 40% of the total investment to the railways .

3. Requirements of Ideal Permanent Way Gauge: Correct & Uniform Cross Levels: Straight/Curved Sections Alignment: Straight & Free of Kinks Gradients: Uniform & Gentle Track: Resilient & Elastic Drainage: Stability, No Water-logging Lateral Strength: Shocks, Vibrations Easy Replacement or Renewal of Components Cost: Minimum (Construction Operation & Maintenance)

4. Components of Permanent Way The Main Components of Permanent Way are as Follows: Rails Sleepers (or Ties) Fasteners Ballast (or Slab Track) Sub grade

5. Track Components

6. Gauge: Defined as the minimum distance between two rails. Rails: They act as girders to transmit the wheel load to the sleepers. Sleepers: They hold the rails in proper position with respect to their proper tilt, gauge and level and transmit the load from rails to the ballast. Ballast: Ballast is a high quality crushed stone with desired specifications placed directly below the sleeper. Ballast distributes the load over the formation and holds the sleepers in position and also functions as drainage layer. Formation: Formation is the compacted and prepared subgrade which is the part of embankment or cutting.

7. Natural subgrade: It is the soil in the natural ground on which the track rests. Ballast cushion: The depth of ballast below the bottom of the sleeper, normally measured under rail seat is termed as ballast cushion. Ballast shoulder: Ballast provided beyond the sleeper edge is termed as ballast shoulder Ballast base: It is the bottom width of ballast bed (typically 4.4 m in a BG track) . Formation width: It is the top width of embankment or bottom width of cutting (typically 6.1 m in a BG track) Cess width: Width of formation beyond the toe of ballast is termed as cess width.

8. Load Transfer

9. Gauge The gauge of a railway track is defined as the clear minimum perpendicular distance between the inner faces of the two rails.

10. Various gauges on Indian Railways The different gauges in India are of the following these types : Broad gauge ( 1676 mm), Meter gauge ( 1000 mm), Narrow gauge (762 mm & 610 mm )

11. Selection of Gauge Cost of construction: There is marginal increase in the cost of earthwork, rails, sleepers, ballast, and other track items with gauge. The cost of station buildings, platforms, signals, bridges, tunnels and culverts etc., is same more or less for all gauges. There is little proportional in the acquisition of land. The cost of rolling stock is independent of the guage used for same volume of traffic . Volume and nature of traffic: For heavier loads and high speed, the wider gauge are required because subsequently the operating cost per tonne -km is less for higher carrying capacity.

12. Speed of movement: Speed is a function of dia. of wheel, which in turn limited by the gauge. (wheel diameter = 0.75 x Gauge). Development of areas: Narrow gauges can be used for thinly populated area by joining under developed area with developed or urbanised area. Physical features of the country: Use of narrow gauge is warranted in hilly regions where broad and meter gauge are not possible due steep gradients and sharp curves.

13. Loading Gauge The loading gauge represents the maximum width and height to which a rolling stock, namely, a locomotive, coach, or wagon, can be built or loaded. In order to ensure that the wagons are not overloaded, a physical barrier is made by constructing a structure. This structure consists of a vertical post with an arm from which a steel arc is suspended from the top. The function of this structure is to ensure that the topmost and the widest portion of the load will clear all structures such as bridges and tunnels, etc. along the route .

14. Construction Gauge The construction gauge is decided by adding the necessary clearance to the loading gauge so that vehicles can move safely at the prescribed speed without any infringement. The various fixed structures on railway lines such as bridges, tunnels, and platform sheds are built in accordance with the construction gauge so that the sides and top remain clear of the loading gauge.

15. Rails The high carbon rolled steel sections , which are laid end-to-end, in two parallel lines over sleepers to provide continuous and leveled surface for the trains to move and for carrying axle loads of the rolling stock are called rails.

16. Scabbing Rail

17. Rail Rail

18. Functions of Rails It provides a continuous & level surface for movement of trains . It provides a smooth & less friction pathway . Friction between the steel wheel & steel rail is about 1/5th of friction between pneumatic tyre & metalled road. It serves as a lateral guide for the wheels . It bear the stresses developed due to vertical loads transmitted to them – through axles & wheels of rolling stock as well as – due to braking & thermal forces. It transmits the load to a large area of the formation through sleepers & the ballast.

19. Requirements of Rails Rail should have the most economical section consistent with – Strength, Stiffness & Durability . Centre of Gravity of rail section should preferably be very close to the mid-height of the rail so that the maximum tensile & compressive stresses are equal. Tensile strength of rail should not be < 72 kg/m 2 To bring down the contact stresses to minimum level, the contact area between the rail and wheel should be as large as possible.

20. Rail head: adequate DEPTH to allow for vertical wear & sufficiently WIDE so that it has a wider running surface available & also has desired lateral stiffness. Rail Web: sufficiently thick to withstand stresses arising due to loads bone by it, after allowing for normal corrosion. Rail Foot: sufficient THICKNESS to withstand VR & Hz forces after allowing for loss of corrosion. Fishing angle: it must ensure proper transmission of loads from the rails to the fish plates. Rail Height: adequate so that rail has sufficient vertical stiffness & strength as a beam.

21. Composition of rail steel For ordinary rails : Carbon ( C) - 0.55 to 0.68 percent Manganese ( Mn ) - 0.65 to 0.9 percent Silicon (Si) - 0.05 to 0.3 percent Sulphur (S) – 0.05 percent or below Phosphorus (P) – 0.06 percent or below For rails at points and crossings : Carbon (C) - 0.5 to 0.6 percent Manganese ( Mn ) - 0.95 to 1.25 percent Silicon (Si) - 0.05 to 0.2 percent Sulphur (S) – 0.06 percent or below Phosphorus (P) – 0.06 percent or below

22. Types of Rails The rails used in the construction of railway track are of following types: Double headed rails (D. H. Rails ) Bull headed rails ( B . H. Rails ) Flat footed rails ( F . F. Rails )

23. Double Headed Rails The rail sections, whose foot and head are of same dimensions , are called Double headed or Dumb-bell rails. In the beginning, these rails were widely used in the railway track. The idea behind using these rails was that when the head had worn out due to rubbing action of wheels, the rails could be inverted and reused . But by experience it was found that their foot could not be used as running surface because it also got corrugated under the impact of wheel loads. This type of rail is not in use in Indian Railways now-a days.

24. Bull Headed Rails The rail section whose head dimensions are more than that of their foot are called bull headed rails. In this type of rail the head is made little thicker and stronger than the lower part by adding more metal to it. These rails also require chairs for holding them in position . Bull headed rails are especially used for making points and crossings.

25. Merits: B.H . Rails keep better alignment and provide more smoother and stronger track . These rails provide longer life to wooden sleepers and greater stability to the track . These rails are easily removed from sleepers and hence renewal of track is easy. Demerits: B.H . rails require additional cost of iron chairs . These rails require heavy maintenance cost . B.H . rails are of less strength and stiffness.

26. Flat Footed Rails The rail sections having their foot rolled to flat are called flat footed or vignole’s rails. This type of rail was invented by Charles Vignole in 1836. It was initially thought that the flat footed rails could by fixed directly to wooden sleepers and would eliminate chairs and keys required for the B.H. rails. But later on, it was observed that heavy train loads caused the foot of the rail to sink into the sleepers and making the spikes loose. To remove this defect, steel bearing plates were used in between flat footed rails and the wooden sleeper. These rails are most commonly used in India.

27. Merits: F.F . rails have more strength and stiffness. No chairs are required for holding them in position. These rails require less number of fastenings . The maintenance cost of track formed with F.F. rails is less. Demerits: The fittings get loosened more frequently. These rails are not easily removed and hence renewal of track becomes difficult. It is difficult to manufacture points and crossings by using these rails.

28. Standard Rail Sections The rail is designated by its weight per unit length. In FPS Units , it is the weight in lbs per yard and in Metric Units it is in kg per metre . A 52 kg/m rail denotes that it has a weight of 52 kg per metre . FPS : Foot-pound-second System MKS : Meter Kilogram Second system

29. Standard Rail Sections in Indian Railway MR (IRS) stands for Metric Rail (Kg/m) as per Indian Rail Standards R  (RBS ) stands for British Rail ( lbs / yd ) as per Revised British Standards Recently Introduced in IR

30. Standard Rail Sections & Rail Length in IR Gauge Rail section Type of section Rail length Rail section Kg/m   Broad gauge 60 kg/m 60 MR ( UJC ) 13 m (42 ft as per old standards) 60.34 60 MR 52 kg/m 52 MR (IRS) 51.89 52 MR 90 lb/ yd 90 R (RBS) 44.61 45 MR Metre gauge 90 lb/ yd 90 R (RBS) 12 m (39 ft as per old standards), except 90-lb rails, which are of 13 m length 44.61 45 MR 75 lb/ yd 75 R (RBS) 37.13 37 MR 60 lb/ yd 60 R (RBS) 29.76 30 MR Narrow gauge 50 lb/ yd 50 R (RBS) 12 m (39 ft as per old standards) 24.8 25 MR MR stands for Metric Rail R stands for Revised British Specifications

31. Details of Standard Rail Sections for BG on IR 90 R rail section was considered adequate only for Annual traffic density of about 10 GMT (gross million tonnes per km/annum), Speeds of up to 100 kmph , Axle loads up to main line (ML) standard, and Service life of about 20-25 years.

32. Realizing to these limitations, the Indian Railways, in the year 1959 , designed a heavier rail section of 52 kg/m to meet the requirements of heavier and faster traffic. 52 kg/m rail section was recommended for use on all BG main line routes with Future speeds of up to 130 kmph and Traffic density of 20-25 GMT. 

33. The traffic density on the BG track routes of Indian Railways is increasing very fast. Accordingly , to meet the future requirements of traffic, a new design has been finalized for the 60-kg UIC section rail . 60 Kg/m rail section has been designed for Speeds of up to 160 kmph and Traffic density of about 35 GMT.

34. Choice of Rail Section Designated by weight per unit length FPS : lb/yard (e.g. 90 lb/yard) MKS : kg/m (e.g. 52 kg/m) Factors affecting choice of rail section Heaviest axle load Maximum permissible speed Depth of ballast cushion Type and spacing of sleeper Rule of thumb: Max axle load = 560 x S ectional weight of rail lb/yard or kg/m Max axle load for 52 kg/m rail= 560* 52 =29.12 tonne

35. Brand Marks on the Rails

36. Every rail rolled has a brand marks on its web. It should be rolled in letters at least 20 mm in size and 1.5 mm in height at intervals of 1.5 to 3.0 m . As per IRS-T-12-88, the brand marks are as follows: IRS : Indian railway standards specification , 52 kg : Rail section as 52 kg/m 710 : Grade of the rail . (There is 2 grades of the rail one is the 710 another is 880 grade) TISCO : Name of the company (Tata Iron and Steel Co . ) II 1991 : Month and year of manufacture (February 1991) → : An arrow showing the direction of the top of the ingot Process of steel making OB : Process of Steel Making ( Open Hearth Basic) IRS - 52 kg - 710 - TISCO - II 1991 → OB

37. Except Rail wear and the battering of rail ends some other types of defects may also develop in a rail as below. Buckling of Rails Hogging of rail Scabbing of rail Wheel burns Shelling and black spots Corrugation of rails Kinks Defects in rails

38. Buckling of Rails: Buckling means the track has gone out of its original position or alignment due to prevention of expansion of rails in hot weather on account of temperature variations. Buckling Buckling

39. Buckling Buckling

40. Hogging of rail: The rails which are bent vertically at the ends are known as hogged rails and they are formed due to wear of rails on ends. Rail ends get hogged due to poor maintenance of the rail joint, yielding formation, loose and faulty fastenings, and other such reasons. Hogging of rails causes the quality of the track to deteriorate. This defect can be remedied by measured shovel packing. Buckling Hogging

41. Hogging Hogging Hogging

42. Scabbing of rail   The scabbing of rails occurs due to the falling of patches or chunks of metal from the rail table. Scabbing is generally seen in the shape of an elliptical depression, whose surface reveals a progressive fracture with numerous cracks around it. Scabbing Scabbing

43. Scabbing Scabbing Scabbing

44. Wheel burns: Wheel burns are caused by the slipping of the driving wheel of locomotives on the rail surface. As a consequence, extra heat is generated and the surface of the rail gets affected, resulting in a depression on the rail table. Wheel burns are generally noticed on steep gradients or where there are heavy incidences of braking or near water columns.

45. Shelling and black spots: Shelling is the progressive horizontal separation of metal that occurs on the gauge side, generally at the upper gauge corner. It is primarily caused by heavy bearing pressure on a small area of contact , which produces heavy internal shear stresses.

46. Corrugation of rails In certain places, the heads of the rails are found not straight but corrugated i.e., with a wavy surface. This phenomena is called Corrugation and the rails are called Corrugated Rails . Corrugation consists of minute depressions on the surface of rails , varying in shape and size and occurring at irregular intervals .

47. Kinks When the ends of adjoining rails move slightly out of position , “shoulders” or “kinks” are formed.

48. Rail Wear The separation or cutting of rail due to friction and abnormal heavy load is called wear . There are three types of wears of rail On the basis of the position of wear : Vertical wear: Wear of Rails On top of rail head Lateral wear: Wear at the sides of the rail head Battering of rail end: Wear at the end of rail  

49. 1) Vertical wear The metal from the top of rail flows and forms projections which are known as burrs . Burr

50. The causes of such types of wear are: Rails are worn out on top due to abrasion of the rolling wheels over them. The heavy wheel loads are concentrated on very small areas. Impact of heavy loads Corrosion of metal of rails Due to slipping action of wheels during starting and when brakes are applied to the moving trains, the metal of top of rail burns.

51. Railhead Wear and Side Cut Gauge

52. Rail Head Wear Measuring Instrument

53. Lateral wear This is the most destructive type of wear and occurs on the rails laid on curves.

54. The various causes of side wear of rails are: Due to centrifugal force along the curvature, the grinding action of wheel flanges on the inner side of the head of the rails is caused. The vehicles do not bend to the shape of the curvature while moving over a curve. This results into the biting of the inner side of the head of outer rail by wheel flanges. The wear on the inner side of the head of inner rail is mainly due to the slipping action of wheel on curve.

55. Outer wheels have to cover a longer distance than inner wheel as “ pq ” is greater than “ rs ”. But due to rigid connection between two wheels, they cover the same distance and hence then inner wheel slips over the inner rail, resulting in the wear of inner side of head of inner rail.

56. Battering of rail end This wear of rails takes place at the ends of rails and is found to be very much greater than the wear at the top of rails. At the expansion gap , the wheels of the vehicle have to take a jump and during this jump, they impart a blow is the ends of the rails. This blow is the main cause of wear of rails at ends. Due to successive blows, the ends of the rails are battered.

57. Types of Wear on  the basis of location Wear is more prominent at some special locations of the track. These locations are normally the following: On sharp curves – Due to centrifugal forces On steep gradient s – Extra force applied by the engine On approaches to stations – Acceleration and deceleration Tunnels and coastal areas – Humidity and moisture

58. Methods to Reduce Wear Use of Special Alloy Steel At places where, wear of rail is considerable, special alloy steel rails are used. The cost of such rail is more but considerable reduction of wear of such rails justifies the extra cost. Good Maintenance of Track The track should be carefully looked after and joints should be tightened if they become loose. A well maintained track would definitely result in less wear of rails. Reduction of Expansion Gap If the expansion gap has increased beyond a certain limit, it should be reduced by packing the sleepers at the joints and tightening fish bolts . This will result in the reduction of wear of end of rails.

59. Exchange of Inner and Outer Rails on Curves Mostly on curves , where there is heavy wear at the top of head of inner rail and heavy wear of the side of head of outer rail then the top wear inner rail is exchanged with the side wear outer rail and thereby life of rail is increased. Use of Lubricating Oil The wear of rails can also be reduced by applying lubricating oil on curves on the side of head of rails . The lubrication of rails can be carried out manually or by mechanical equipment attached to locomotive for rail.

60. Providing check rails in sharp curves Coning of wheels and tilting of rails By welding or de hogging of battered ends of rails in time. By application of heavy mineral oil under adverse atmosphere. By using bearing plates . By regular tightening of fish bolts and packing of ballast .

61. Creep of Rails Creep in rail is defined as the longitudinal movement of the rails in the track in the direction of motion of locomotives. Creep is common to all railways and its value varies from almost nothing to about 6 inches or 16 cm. Indications of creep: Closing of successive expansion spaces at rail joints in the direction of creep and opening out of joints at the point from where creep starts. Marks on flanges and webs of rails made by spike heads by scratching as the rail slide.

62. Due to creep of rails, gap between railway track at one end gradually deforms until it disappears and even expands the rail. The gap between railway track at the other end are stretched, causing fishplate bolts to be pulled or broken.

63. Theories f or the Development of Creep The important theories for creep development are: Brakes Wave action or wave theory Percussion theory  

64. 1) Brakes / Drag Theory Drag Theory According to drag theory, the backward thrust of the driving wheels of a locomotive has the tendency to push the rail backwards, while the thrust of the other wheels of the locomotive pushes the rail in the direction in which the locomotive is moving. This results in the longitudinal movement of the rail in the direction of traffic, thereby causing creep. Force acting at the time of starting, accelerating, slowing down or stopping the train causes creep.

65. As shown in the figure during the starting operation, the wheel pushes the rail backward, while during the stopping operation the rails are pushed forward.

66. 2) Wave Action or Wave Theory Creep is developed due to wave motion of wheels on rails. Due to the load of the wheel, the portion of the rail under load is depressed slightly. As the wheels move, the depression also moves with them and previous depressed portion regains their original level. Thus under the wheel of a train, wave motion is developed. This wave motion tends the rail to move forward.

67. 3) Percussion Theory According to percussion theory, creep is developed due to the impact of wheels at the rail end ahead of a joint.

68. The horizontal component p of reaction R tends to creep and the vertical component tends to bend the rail end vertically i.e. to better the rail end. Thus as and when wheels leave the trailing rail and strike the facing rail end at each joint, it pushes the rail forward resulting in creep. Though the impact of a single wheel may be nominal, the continuous movement of several of wheels passing over the joint pushes the facing or landing rail forward, thereby causing creep. 

69. The main factors responsible for the development of creep are as follows.  Ironing effect of the wheel  The ironing effect of moving wheels on the waves   formed in the rail tends to cause the rail to move in the direction of traffic, resulting in creep . Changes in temperature  Creep can also develop due to variations in temperature   resulting in the expansion and contraction of the rail. Creep occurs frequently during hot weather conditions. Unbalanced traffic   In a double-line section, trains move only in one direction,   i.e., each track is unidirectional. Creep, therefore, develops in the direction of traffic. In a single-line section, even though traffic moves in both directions, the volume of the traffic in each direction is normally variable. Creep, therefore, develops in the direction of predominant traffic. Causes of creep

70. Starting and stopping operations  When a train starts or accelerates, the backward   thrust of its wheels tends to push the rail backwards. Similarly , when the train slows down or comes to a halt, the effect of the applied brakes tends to push the rail forward. This in turn causes creep in one direction or the other .

71. Poor maintenance of track: Improper securing of rails to sleepers Limited quantities of ballast resulting in inadequate ballast resistance to the movement of sleeper   Improper expansion gaps Badly maintained rail joints Rail seat wear in metal sleeper track Rails too light for the traffic carried on them Yielding formations that result in uneven cross levels Other miscellaneous factors such as lack of drainage , and loose packing , uneven spacing of sleepers .

72. Factors Effecting the Magnitude & Direction of Creep Alignment of track: Creep is more on curves than on tangent tracks. Grade of track: More in case of steep curves , particularly while train moving downward with heavy loads. Type of rails: older rail have more tendency than new one. Direction of heaviest traffic: In heavier load moving direction occurs more creep.

73. Effects of Creep The following are the common effects of creep Sleepers out of square:   The sleepers move out of their position as a result of   creep and become out of square. This in turn affects the gauge and alignment of the track, which finally results in unpleasant rides

74. Distance in gaps get disturbed : Due to creep, the expansion gaps widen at   some places and close at others . This results in the joints getting jammed . Undue stresses are created in the fish plates and bolts, which affects the smooth working of the switch expansion joints in the case of long welded rails.

75. Distortion of points and crossings : Due to excessive creep, it becomes difficult   to maintain the correct gauge and alignment of the rails at points and crossings Difficulty in changing rails  If , due to operational reasons, it is required that the   rail be changed, the same becomes difficult as the new rail is found to be either too short or too long because of creep. Effect on interlocking   The interlocking mechanism of the points and crossings   gets disturbed by creep.

76. Possible buckling of track  If the creep is excessive and there is negligence in the   maintenance of the track, the possibility of buckling of the track cannot be ruled out. Other effects  There are other miscellaneous effects of creep such as breaking of   bolts and kinks in the alignment, which occur in various situations.

77. Remedies of Creep Pulling back the rails: Pull back the rail to its original position by means of crow bars and hooks provided through the fish bolts wholes of rails By considering the position of joints relative to sleepers and both rails should be in respective position. Provision of anchors: By use of anchors and sufficient crib ballast. For creep 7.5 cm-15 cm 4 anchors per rail For creep 22.5 to 25 cm 6 anchors. Use of steel sleepers: Sleepers should be made up of good material with proper fitting. Sleepers should provide good grip with ballast to resist the movement of sleepers. Increase in no. Of sleepers . Increase in sleeper density

78. crow bars

79. Rail anchor is designed to eliminate creep of track. The rail anchors provide a large bearing surface against both rail base and tie, avoiding undo cutting and wear, thus prolonging the life of wooden ties.

80. Fair V Anchor

81. Hydraulic rail tensioner

82. Ballast Cribber

83. Rail Joints

84. Rail Joint Rail joints are necessary to hold the adjoining ends of the rails in the correct position, both in the horizontal and vertical planes Weakest part of the track In order to Provide expansion and contraction due to variation in temperature, certain gap is provided at each joint. This gap causes a break in continuity of rails in horizontal as well as in vertical plane, forming the weakest point of the track.

85. Types of Rail Joints According to Position of joints Square joints Staggered joints According to position of sleepers Suspended joints Supported joints Bridge joints Insulated joint Compromise joint

86. According to Position of joints Square Joints: Joint in one rail is exactly opposite to the joint in the other parallel rail is called as Square Joint Common in straight tracks Square Rail Joints

87. Staggered Joints: Joint in one rail is exactly opposite to the centre of the other parallel rail is called as Staggered Joint. In India this type of joint is used in curves. It gives smoother running to the track. Staggered Rail Joints

88. According to Position of Sleepers Suspended joints: The rail joint when placed at the centre of two consecutive sleepers is known as suspended joints The load is evenly distributed on two sleepers. When joint is depressed both rails are pressed down evenly Suspended Rail Joint

89. Supported joints: When the sleeper is placed exactly below the rail joint , it is known as supported joint. Do not give sufficient support with heavy axle loads. Supported Rail Joints

90. Bridge joints: Similar to suspended joint, but a metal serving as a bridge to connect the ends of two rails The bridge is placed at the bottom of rails and it rests on two sleepers

91. Bridge Joint with Metal Flat Bridge Joint with Bridge Plate

92. Welding of Rail Joint

93. Welding a Rail Joint The purpose of welding is to join rail ends together by the application of heat and thus eliminate the evil effects of rail joints. There are four welding methods used on railways. Gas pressure welding Electric arc or metal arc welding Flash butt welding Thermit welding

94. 1.Gas Pressure Welding In this type of welding, the necessary heat is produced by the combination of oxygen and acetylene gases. The rail ends to be welded are brought together and heat is applied through a burner connected to oxygen and acetylene cylinders by means of regulators and tubes. A temperature of about 1200°C is achieved. At this temperature, the metal of the rail ends melts , resulting in the fusion and welding together of the ends.

95. The rails to be welded are clamped at the wall by applying a pressure of 40 t pressure, heated to a temperature of about 1200 ° C to 1400 ° C , and butted with an upset pressure of about 20 t. Then the joint is again heated to a temperature of 850 ° C and allowed to cool naturally. It has been seen that this method of welding is cheaper as compared to flash butt welding. The quality of this welding joint is also claimed to be quite good. There are both stationary and mobile units available for gas pressure welding.

96. The process has not yet been adopted on a large scale by Indian Railways. The main reason behind this is its limited output and the difficult and irregular availability of gas. India has only one plant that offers gas pressure welding, which is located at Bandel on the Eastern Railways and the progress in this plant has been nominal .  

97. 2.Electric or Metal Arc Welding In this method, heat is generated by passing an electric current across a gap between two conductors . A metal electrode is energized by a voltage source and then brought close to another metal object, thereby producing an arc of electric current between the two objects. A lot of heat is generated by this electric arc, causing the two rail ends to fuse or weld.

98. This type of welding can be done using any of the following methods. Insert Plate Technique Scheron Process Enclosed Space Technique Indian Railways has recently started welding rail joints using the metal arc process on a trial basis and the performance so far has been satisfactory.

99. 3.Flash Butt Welding In flash butt welding, heat is generated by the electric resistance method . The ends of the two rails to be welded are firmly clamped into the jaws of a welding machine. One of the jaws is stationary, while the other one is moveable and as such the gap between the two rail ends can be adjusted. The rail ends are brought so close together that they almost touch each other. An electric current of 35 kA is passed between the interfaces of the two rails, developing a voltage of 5 V . A lot of flashing (sparking) occurs and considerable heat is generated by the passage of electrical current between the rail ends. The rail ends are automatically moved to and fro by the machine till the temperature rises to a fusion limit in the range of 1000°C to 1500°C. At this time, the rail ends are pressed together with pressure and final flashing takes place joining the two rail ends together. High-quality welded joints are produced by the flash butt welding method.

100. https://www.gleisbau-welt.de/encyclopedia/maintenance-of-way/mechanised-track-laying/welding-technology/flash-butt-welding/

101. Flash Butt Welding

102. 4.Thermit Welding of Rails This is the only form of site welding which is being adopted universally. The method was first developed by Gold Schmidt of Germany towards the end of the nineteenth century. A code of practice for welding rail joints using the alumino-thermic process has been developed by Indian Railways. The code defines the method of welding and the precautions and steps to be taken before, during, and after welding for the production of satisfactory weld joints.

103. General Principle : The principle behind this process is that when a mixture of finely divided Aluminium & Iron Oxide , called Thermit Mixture , is ignited, a chemical reaction takes place which results in the evolution of heat and the production of iron and aluminium oxide: Fe 2 O 3  + 2Al = 2Al 2 O 3  + 2Fe + heat In this reaction, 159 g of iron oxide combines with 54 g of aluminium to give 102 g of aluminium oxide, 112 g of iron, and 182 kcal of heat. The reaction is exothermic and it takes about 15-25 sec to achieve a temperature of about 2450°C. The released iron is in the molten state and welds the rail ends, which are kept enveloped in molten boxes. The aluminium oxide, being lighter however, floats on top and forms the slag.

104. Thermit Welding of Rails

105. Track Fittings & Fastenings

106. Track Fittings & Fastenings Track fittings and rail fastenings are used to keep the rails in the proper position and to set the points and crossings properly. They link the rails endwise and fix the rails either on chairs fixed to sleepers or directly on to the sleepers. The important fittings commonly used are: 1. Fish plates 2. Spikes 3. Bolts 4. Chairs 5. Blocks 6. Keys 7. plates

107. Types of track fittings 1 Joining rail to rail Fish plates, combination fish plates, bolts, and nuts 2 Joining rail to wooden sleepers Dog spikes, fang bolts, screw spikes, and bearing plates 3 Joining rail to steel trough sleepers Loose jaws, keys, and liners 4 Joining rail to cast iron sleepers Tie bars and cotters 5 Elastic fastenings to be used with concrete, steel, and wooden sleepers Elastic or Pandrol clip, IRN 202 clip, HM fastening, rubber pads, and nylon liners

108. Fish Plates The name 'fish plate' derives from the fish-shaped section of this fitting. Fishplate, splice bar or joint bar is a metal bar that is bolted to the ends of two rails to join them together in a track. They maintain the continuity of rails & allow expansion and contraction of rail due to temperature difference. They Maintain correct alignment of line both horizontally & vertically. Fishplate is a small copper or nickel silver plate that slips onto both rails.

109. Fish Bolts Made up of medium or high carbon steel. Fish bolts have to undergo shear due to heavy transverse stresses . Length depends on the type of fishplate used. For 44.70Kg rail, a bolt of 2.5cm dia and 12.7cm length is used. These bolts get loose by the traffic variations and require tightening from time to time.

110. Spikes A rail spike is a large nail with an offset head that is used to secure rails and base plates to rail road ties in the track.

111. Requirements of good spikes The spike should be… Strong enough to hold rail in position & enough resistance to motion to retain its position. Cheap in cost Deep as possible for better holding power Easy in fixing and removal from sleepers Capable of maintaining the gauge

112. 1. Dog Spikes Commonly used Hold rail flanges with timber sleepers Shape of head of spike resembles ear of dog , hence called dog spike Section of spike is square – shape & bottom part is either pointed or chisel shaped Cheapest Easy in fixing and removing from sleepers Maintain better gauges

113. 2. Screw Spikes Tapered screws with V- threads used to fasten rails with timber sleepers . Head is circular with square projection Holding power is double than that of dog- spike Resist lateral thrust in better way More costly Gauge maintenance is more difficult Driving operations are similar to dog -spikes

114. 3. Round Spikes Head either cylindrical or hemispherical Used for fixing chairs of bull headed rails to wooden sleepers Limited use only

115. 4. Elastic Spikes This spikes absorbs the wave motion of rail without getting it loose. Provide better grip and result in reduction of wear and tear of rail. Commonly used in British railways

116. Chairs Chairs are required to hold bull headed rails and double headed rails in position Made of cast iron and help in distributing the load from the rails to thee sleepers It consists of two jaws and a rail seat. The web of the rail is held tightly against the inner jaws of the chair and a key is driven between the rail and the outer jaw of the chair The chair are fixed with the sleepers by means of spikes The shapes of chairs depend upon the type of rails used.

117. Keys are small tapered pieces of timber or steel to fix rails to chairs on metal sleepers. Keys may be either straight or tapered . Types of keys are: Wooden key for C.I. chair M.S. key for steel through sleepers Stuart’s key Morgan key Cotter and tie bars Wooden keys are cheap Initial cost of steel keys is high. But life is about ten times more than wooden keys. So steel keys are preferred. Keys

118. KEY

119. KEY KEY

120. Bearing Plates Bearing plates are rectangular plates of mild steel or cast iron used below F.F rails to distribute the load on larger area of timber sleeper. Advantages: To distribute the load coming on rails to the sleepers over a larger area and to prevent skidding of the rail in the soft wooden sleepers. Prevent the destruction of the sleeper due to rubbing action of the rail. Adzing of sleeper can be avoided by bearing plates.

121. Disadvantages: Plates rattle when loose When any hole for a spike is failed and a new hole is to be made , all spikes in the bearing plate have to be pulled out which affects good hold of spikes. When bearing plates are loose , they admit moisture and result in mechanical wear of sleepers

122. Blocks Types of blocks: Heel blocks Distance blocks Check block Crossing block

123. Ballast Ballast

124. Ballast Ballast is a layer of broken stones, gravel or any other such gritty material laid and packed below and around sleepers . Railway Ballast is the foundation of railway track and provide just below the sleepers. The loads from the wheels of trains ultimately come on the ballast through rails and sleepers.

125. Ballast

126. Functions of Ballast It provides levelled bed or support for the railway sleepers. It transfers the load from sleepers to subgrade and distributes the load uniformly on subgrade. It prevents the longitudinal and lateral movement of sleepers. It offers good drainage to the track. It drain off the water quickly and to keep the sleepers in dry conditions. It discourage the growth of vegetation. It hold the sleepers in position during the passage of trains.

127. Requirements for Ideal Ballast The ideal material for ballast should fulfill the following requirements: It should be possible to maintain the required depth of the material in order to distribute the load of passing train on the formation ground The material to be used for ballast should not be too rigid but it should be elastic in nature The material for ballast should be of such nature that it grips the sleepers in position and prevent their horizontal movement during passage of train It should not allow the rain water to accumulate but should be able to drain off the water immediately without percolating It should be strong enough a resistance to abrasion

128. Materials Used for Ballast The following materials are used for ballast on the railway track. Broken Stone Gravel Cinders / Ashes Sand Kankar Moorum Brick Ballast

129. Types of Ballast According to Material 1. Broken stone Ballast Broken stone is a widely used ballast in railways. It is obtained by crushing hard stones like granite, hard trap, quartzite etc. limestone and sandstone can also be used. It is suitable for high-speed railway tracks. The broken stone selected as ballast should be hard, tough and non-porous. It should stay strong against bad weather conditions.

130. Benefits of Broken Stone Ballast: Broken stones are hard, tough and durable . Hold the sleepers in a strong position and provide stability to the track. Suitable for heavy traffic tracks and for high-speed tracks. Economical with respect to their durability. Require less maintenance. Drawbacks of Broken Stone Ballast: Since broken stones are not easily available, their initial cost is a little high. Produce noise when the train is moving on the track. They are sharp and angular and hence wooden sleepers may be liable to damage by these broken stones.

131. 2. Sand Ballast Sand can also be used as a ballast material. It is well suitable under cast iron sleepers and can be seen in desert railway tracks where plenty of sand gets accrued on the track. Coarse sand is best suitable as ballast than fine sand.

132. Benefits of Sand Ballast It provides excellent drainage facilities to the track. Well suitable for Cast iron sleepers and does not produce any noise while the train is moving on track. Cheap and abundantly available material. Drawbacks of Sand Ballast Sand may blow off easily due to vibrations produced by train or due to high winds. So, a frequent renewal is required. Excessive wear of sleepers and moving parts can occur due to friction developed by sand.

133. 3. Gravel Ballast Gravel is a naturally occurring material formed by the erosion of rocks. They are suitable for all types of sleepers and are usually round and smooth and can be obtained from river beds, gravel pits etc.

134. Benefits of Gravel Ballast: It occurs naturally and hence is cheap and easily available. Properly cleaned gravel offers excellent drainage facilities to the track. Well packed gravel requires less maintenance and has high durability. Drawbacks of Gravel Ballast: Because of their smoothness and roundness, they may get separated from the bed under vibrations . Since it occurs naturally, it may contain some amount of earth or clay which should be cleaned. If not cleaned, the drainage properties of gravel may get affected. Sieving should be done to eliminate small size gravel particles otherwise they may affect the drainage properties. Produce noise when the train is moving on the track .

135. 4. Moorum Ballast: Moorum is formed by the decomposition of laterite. It is available mostly in red color and, sometimes, in yellow. If the track is to be laid on black cotton soil, moorum can be used as a blanketing material or sub-ballast since it prevents permeability of water into the subgrade or formation.

136. Benefits of Moorum Ballast Moorum is good as a sub-ballast especially in the case of weak soil subgrades. Provides good aesthetics to the track. Drawbacks of Moorum Ballast It is very soft and when subjected to vibrations gets converted into a powdered form and blows away . It requires frequent maintenance. Not recommended unless there is no other material available.

137. 5. Coal Ash or Cinder Ballast Coal ash also called cinder is the by-product of coal-fired power plants and railway locomotives. It can be used as a ballast material since it is cheaply available and also possesses good drainage properties. It is used as a ballast especially for station yards and as initial ballast for newly constructed tracks.

138. Benefits of Coal Ash Ballast It is economical and abundantly available. It has excellent drainage properties. It can be handled with ease and is light in weight. Drawbacks of Coal Ash Ballast Turns into dust when subjected to loads. Makes the track dirty and complicates the maintenance procedure. It is not recommended when steel sleepers are used because of its corrosive action. The rails may also get affected by the corrosive action of coal ash.

139. 6. Brickbat Ballast Brickbats are nothing but crushed pieces of bricks which are generally over-burnt. Under-burnt brickbats are not suitable since they are not as porous as over-burnt brickbats.

140. Benefits of Brickbat Ballast Porous brickbats have good drainage properties. Brickbats are useless products of brick industries and hence can be bought at cheap prices. Drawbacks of Brickbat Ballast When subjected to loads they turn into a powder which can be easily blown away by the wind. The brick dust makes the track dirty and demands frequent maintenance.

141. Sleepers

142. Sleepers Wooden , cast iron, steel or RCC members which are laid transverse to the track alignment to Support the rails and to transfer the load from the rails to the under line blast are called sleepers. Railway sleepers also called railroad ties, railway ties or crossties.

143. Functions of sleepers Hold rails to correct gauge & alignment Holding gauge in proper level Act as elastic medium Support the rails firmly & evenly Distribute the load transmitted from the rolling stock over large of ballast Provides stability to permanent way To provide the insulation of track for the electric field tracks of signaling To provide easy replacement of rails fastening

144. Requirements of Ideal Sleeper The sleepers to be used should be economical , i.e they should have minimum possible initial & maintenance cost. Moderate weight – easy to handle. Fixing & removing of fastenings should be easy . Sufficient bearing area . Easy maintenance & gauge adjustment. Track circuiting (electric insulation) must be possible. Able to resist shocks & vibrations.

145. Types of Sleeper Depending upon the position in a railway track, railway sleepers may be classified as : Longitudinal Sleepers Transverse Sleepers

146. 1. Longitudinal Sleepers: These are the early form of sleepers which are not commonly used nowadays. It consists of slabs of stones or pieces of woods placed parallel to and underneath the rails. To maintain correct gauge of the track, cross pieces are provided at regular intervals.

147. At present this type of sleepers are discarded mainly because of the following reasons. Running of the train is not smooth when this type of sleepers is used. Noise created by the track is considerable. Cost is high.

148. 2. Transverse Sleepers: Transverse sleepers introduced in 1835 and since then they are universally used. They remove the drawbacks of longitudinal sleepers: the transverse sleepers are economical , silent in operation and running of the train over these sleepers is smooth.

149. Depending upon the material, the transverse sleepers may be classified as : Timber or Wooden Sleepers Metal Sleepers Cast iron sleepers Steel sleepers Concrete sleepers Reinforced concrete sleepers Pre - stressed concrete sleepers

150. Wooden Sleepers The timber sleepers nearly fulfilled all the requirements of ideal sleepers and hence they are universally used. Sal, deodar and chir are mostly used as they are cheaper. Teak is not much used due to high cost.

151. Sizes of wooden sleepers and bearing areas

152. Advantages: Low initial cost Few & simple fastening Easy to handle Suitable for all types of ballast Can be used with every type of rail Less damage during accident Easy renewal of track Absorb shocks & vibrations More useful for yielding formations

153. Disadvantages: Short life Liability of decaying Easily attacked by Termite (white ants) & weather Connections between rail and sleepers are not strong Maintenance of gauge is difficult Higher maintenance cost Susceptible to fire Low scrap value

154. Sleeper Dimension: The wide dimension on a crosstie (sleeper) is referred to as a tie face, and the narrow dimension is called the side.

155. Steel Sleeper Steel sleepers having long useful period. steel sleepers are in the form of inverted channels with folded ends & having thickness 12 mm . Ends of rolled sections are flattened in the shape of a spade to retain the ballast.

156. Requirements: Maintain perfect gauge. Should not get pushed easily out of position. Contain high strength. Provide sufficient bearing area of rail.

157. Advantages: Very durable Easy to maintain gauge & lesser maintenance probs. Better lateral rigidity Lesser damage during handling & transport Easy to manufacture Not susceptible to vermin attack Not susceptible to fire attack Good scrap value.

158. Disadvantages: Liable to corrosion Unsuitable for track circuiting areas Liable to become centre bound due to slopes at two ends More fittings are required in number More ballast is required as compared to other types.

159. Cast Iron Sleepers

160. Advantages: Easy to manufacture Lesser liable to crack at rail seats Useful life 50 to 60 years. Provide high lateral & longitudinal stability to track Lesser liable to corrosion Scrap value is high Low maintenance cost

161. Disadvantages: High initial cost Gauge maintenance is difficult as tie bars get bent up Broken easily if not handled carefully Need large number of fittings No elastic bed , so great damage in accidents

162. Concrete / RCC Sleepers

163. Advantages: Concrete sleepers being heavy give more elastic modulus, strength & stability to track Great resistance to buckling of track Best suited for modern maintenance methods for track as they are flat at bottom. They are neither susceptible to be attacked by vermin, corrosion nor are they inflammable Due to longer life , rail and sleeper renewals can be matched. They could be easily manufactured locally with local available materials More life

164. Disadvantages: Manufacturing process, transportation, handling & laying is difficult & costly because they are heavy. Excessive damage can be caused in derailment No scrap value

165. Sleeper less Track

166. Pre-stressed Sleepers Advantages: The P.S.S result in reduced rail pending stresses The P.S.S reduce the wear of rolling stocks. The P.S.S produce less vertical motion. Life 50 years.

167. Disadvantages: Not Economical – high cost. Derailments – heavy damages caused. Maintenance – high cost. Rigidity – more. Scraped no value.

168. Twin-Block Sleepers Lighter by 30% compared to a regular concrete sleeper thus allowing it to be manually moved and the four faces of the two blocks resist movement better. Excellent for some lighter track forms like those used for tramway systems.

169. Plastic sleepers Made of old tires and recycled plastic Cost about 50% less and save on trees Practically impervious to the seasons, but otherwise exhibit the same properties as their wooden counterparts with respect to damping of impact loads, lateral stability, and sound absorption.

170. Coning of Wheels The Surface of wheels are made in cone shape at an inclination of 1 in 20, and the same slope is provided in the rails this is known as coning of wheels.  The coning of wheels is mainly done to maintain the vehicle in the central position with respect to the track.

171. Coning of wheels – Straight and Curved Tracks

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