Rails, Types, Joints, Creep and Welding of Rails, failure of rails

1. Rails, Creep, Failures, Joints and
Welding

2. Definition
 Rails are the members of the track laid in two
parallel lines to provide an unchanging,
continuous, and level surface for the movement
of trains.
 To be able to withstand high amount of stresses
these are made of high carbon steel.

3. Functions of Rails
 Rails are similar to steel girders. These are
provided to perform the following functions in a
track.
 Rails provide a continuous and level surface for the
movement of trains.
 Rails provide a pathway which is smooth and has
very little friction.
 Rails serve as a lateral guide for the wheels.

4. Functions of Rails
 Rails bear the stresses developed due to vertical
loads transmitted to them through axles and wheels
of rolling stock as well as due to braking and
thermal forces.
 Rails carry out the function of transmitting the load
to a large area of the formation through sleepers
and the ballast.

5. Components of Rail

6. Requirements of Ideal rail
 The section of the rail should be such that the
load of each wheels is transferred to the sleepers
without exceeding the permissible stresses
 The section of the rail should be able to withstand
the lateral forces caused due to fast moving
trains.
 The bottom of head and top of foot should be
given such shapes that fishplates can be easily
fitted.

7. Requirements of Ideal rail
 The centre of gravity of the rail section should
preferably coincide the centre of the height of the
rail so that maximum tensile and compressive
stresses are nearly equal.
 The web of the rail section should be such that it
can safely bear the vertical load without buckling.
 The head of the rail should be sufficiently thick for
adequate margin of vertical wear.

8. Requirements of Ideal Rail
 The foot of rail should provide sufficient bearing
area on the underlying sleepers so that the
compressive stresses on the timber sleeper
remain within permissible limits.
 The section of the rails should be such that the
ends of two adjacent rails can be efficiently
jointed with a pair of fish plates.
 The surfaces for rail table and gauge face should
be sufficiently hard to resist the wear.

9. Requirements of Ideal Rail
 The contact area between the rail and wheel
flange should be as large as possible to reduce
the contact stresses.
 The specimen of rail should be able to withstand
the blow of a falling weight in the test specified by
the specifications
 The composition of the steel should conform to
the specifications adopted for its manufacture by
Open Hearth of Duplex Process

10. Requirements of Ideal Rail
 The overall height of the rail should be adequate
to provide sufficient stiffness and strength as a
simply supported beam.
 The foot of the rail should be wide enough so that
the rail is stable against overturning.
 There should be balanced distribution of metal in
head, web and foot.

11. Track components

12. Types of Rails
 Formerly wooden rails are used with thin plates.
Later
 Cast – iron
 Malleable iron
 Wrought iron
 steel
 At present, Classified mainly into 3 types
 Double headed rail
 Bull headed rail
 Flat footed rail

13. Double headed Rail
 Consists of 3 parts
 Upper table
 Web
 Lower table
 Upper and lower tables are identical
 Idea was to double the life of rails – failed
 Long contact with chairs made the surface of
lower table very rough and smooth running of
trains is not possible with them.

14. Double headed Rails
 Now practically out of
use
 Length varies from
610 to 732cm
 Wrought iron was
used to manufacture
these rails

15. Double headed Rails

16. Bull Headed Rails
 The rails sections having their head of more
dimension then that of their foot are known as bull
headed rails.
 These rails consist of
 Head
 Web
 Foot

17. Bull Headed Rails
 The foot is designed
only to properly hold
the wooden keys with
which the rails are
secured to chairs.
 Only to provide
necessary strength to
the rail
 2 cast iron chairs are
required for each
sleeper.

18. Bull Headed Rails

19. Bull headed rails
 Extensively used in England and in some parts of
Europe
 Weight of standard rail of this type is 47kg per
metre on main lines and 42kg for branch lines
 Length of rail is generally 18.29m.

20. Flat footed rails
 Invented by Charles Vignoles in 1836.
 Also called as Vignoles rails.
 In this type of rail, foot is spread out to form a
base.
 Highly popular and most used in railways.
 90% of the present railway track consists of flat
footed rails.

21. Flat footed rails
Advantages
 Chairs: No chairs are required in this form of rails.
Foot of rail is directly spiked to sleepers.
 Economical
 Stiffness: This form of rail is more stiffer both
vertically and laterally than the bull-headed rail of
equal weight.
 Kinks: Less liable to develop kinks and provides a
uniform and more regular surface than bull headed
rails.

22. Flat footed rails
 The flat footed rails
are found to be
cheaper than the bull-
headed rails.
 Load Distribution: The
flat footed rail
distributes the train
load over a great
number of sleepers.
This results in greater
track stability.
 Longer life than bull
headed rails

23. Flat footed rail

24. Standard Rail Section
 Rail designated by its weight for unit length
 Ex: 60kg/m or 60lb/yard etc.,
 Weight and section of rail governed by many
factors
 Gauge of track
 Max. permissible speed
 Type and spacing of sleepers
 Depth of ballast cushion
 Heaviest moving load likely to cross over the rail
 Spacing of sleepers

25.  Maximum axle load that can be carried by a rail
depends on its weight
 In India the capacity will be calculated as follows:
 Max axle load = 560 x sectional weight of rail in
lb/yard or kg/m
 For 52 kg rail, max. axle load = 560 x 52 = 29.12
tonnes

26. Standard sections used in Indian
railways
 Standard rails used in Indian railways are 60kg,
52kg, 90R, 75R, 60R, and 50R
 60kg and 52 kg are introduced recently
 Other rails have units in FPS but now their
dimensions are talked in SI at present.
 R stands for revised british specifications
 IR stands for Indian railwaya

27. Standard rail sections

28. Standard rail sections

29. 5kg/m and 60kg/m standard sections

30.  Rail sections of type 90R are able to carry only
10GMT of annual traffic
 Due to increase in traffic heavier sections i.e., 52
kg and 60 kg are introduced.
 They can withstand annual traffic of 20 to 25GMT
and speed of 130kmph. (52kg)
 35GMT and 160kmph for 60kg section

31. Advantages of heavier rails
 Economical to have durable track by using
heavier rails rather than increasing no of sleepers
 Cost varies as depth of rail, Strength varies
square of depth. Hence heavy rail is economical.
 Stiffness varies as square of weight, strength as
3/2 power of weight.

32. Advantages of heavier rails
 If wheels move over rails of insufficient capacity,
depression and there by additional dragging of
locomotive. Causes wastage of power and
capacity.
 Experiment in USA resulted in the following
things:
 65kg track used over 32km length
 Saving in initial cost over 55.6kg/m rail
 Maintenance (13.4%), sleeper renewals (56.9%),
ballast renewal (23.3%)
 Deflection between 2 sleepers is less in case of
heavy rails for a given load.

33. Criteria for determining length of rails
 Longer the rail lesser the joints and fittings
 Longer rails provide smoother and comfortable
riding of trains
 Following factors govern the length of a rail
 Cost of production
 Difficulties in handling long rails
 lack of facilities for transporting longer rails
 Difficulties in having a bigger expansion joint for
long rails
 Heavy internal thermal stresses
 Minimum rail length is 3.6m. Standard rail length is
different in different countries.

34. Wear on Rails
 Due to the load and movement of wheels on the
surface of rails, rail head gets worn out.
 Main reasons:
 Impact of moving loads
 Effect of the forces of acceleration and deceleration
 braking of wheels
 Abrasion due to rail wheel interaction
 Effects of weather conditions
 Presence of materials such as sand
 Lack of maintenance

35. Wear on Rails
 Lot of material of rail head worn out, causing a
decrease in the weight of rail.
 Loss of weight should not be excessive
 Stresses will exceed permissible values
otherwise.
 Rail renewal has to be done in such cases.

36. Types of Wear on Rails
 Wear of Rail on the top or head of the rail (vertical
wear)
 Wear of rails at the end of rails (battering of rail
ends)
 Wear of rails on the sides of the head of rail
(lateral wear)

37.  Wear of rail is more prominent at some special
locations of the track.
 On sharp curves, due to centrifugal forces
 On steep gradients due to the extra force applied by
the engine
 On approach zones of stations, possibly due to
acceleration and deceleration
 In tunnels and coastal areas, due to humidity and
weather effects.

38. 1. Wear of Rail on the top of Rail
Head
 The metal from the top of rail flows and forms
projections.
 These projections are known as burrs.
 Causes of vertical wear
 Rails worn out on the top due to abrasion of the
rolling wheels over them
 Heavy wheel loads are concentrated on very small
areas. High stresses exceeding the elastic limit are
developed as a result.

39. 1. Wear of Rail on the top of Rail
Head
• Impact of heavy loads
• Grinding action of the sand particles between wheels
and rails
• Corrosion of metal on the rails
• Metal of top rail burns during the starting when
wheels slip or when brakes are applied.

40. Wear of Rails at Ends of Rails
 Takes place at end of rails
 Much greater than the top of rails
 At expansion gaps, train jumps -> impact load
 Causes battering i.e., wear of end
 Other effects seen are as follows:
 Fish plates become loose
 Contact surface between sleepers and rails are
worn out
 Sleepers at expansion joints depressed due to
settlement of ballast

41. 3. Wear of Rail on the Sides of the
head of rail
 Most destructive type of wear
 Occurs mainly at the curves
 Causes are as follows:
 At curvature, due to centrifugal force grinding action
of wheel flanges on the inner side of head
 Vehicles do not bend to the shape of curvature
while moving on the curve resulting in the biting of
the inner side of curve
 Slipping action of wheels on the curves. Outer
wheel has to cover longer distance compared to
inner wheel. But due to rigidity of the wheels they
will cover(rotate) same distance. Hence, inner
wheel slips over inner rail, resulting a wear on the
inner side of the head of inner rail.

42. Methods to Reduce Wear
1. Use of Special alloy steel
o Special alloy rails are used at places where wear
is more
o Cost is more
o But wear is greatly reduced
o Life of rail is increased by 2 to 3 folds on the
curves
o These type of rails are also used for manufacture
of switches and crossings
2. Good maintenance of track
o Proper maintenance like ballast checking, using
lubricants at places etc.,
o Tightening of joints and fittings to decrease wear

43. 3. Reduction of Expansion Gaps
 Should be reduced by increasing no of sleepers
at joints, by tightening fish bolts
 Usage of welded rails to get higher length rails
also decreases expansion joints
4. Exchange of inner and outer rails
 Inner rail and outer rail exchanged at curves to
increase the life of rails

44. 5. Introducing check rails
 Check rail is kept parallel to inner rail all the way at
the curves
 It holds back the flange of inner wheel to move and
prevents damage of outer wheel
 Gap between inner rail and check rail should be
equal to the thickness of the wheel thickness and
side clearance
 44mm for BG and 41mm for MG
 Connected to inner rails with suitable fastenings
 Used when curvature is min 8 degrees in case of
BG and 14 degree in case of MG
 Normally worn rails are used as check rails

45. 6. Use of lubricating oil
 Usage of lubricating oil on curves on the side of
head cases decrease in wear
 Can be done manually or with mechanical
equipment attached to the locomotives or rails
 Allows free expansion of joints and also smooth
flowing of traffic
 Requirements are as follows:
 Should be in the form of paste of workable consistency at
high and low temperatures.

46.  Efficiency should not be affected by dirt, dust and other
atmospheric agencies
 Should be applied only after cleaning the gauge face
 Should not be done at extreme temperatures
 Commonly used lubricants are
 Lime saponified types of grease on a mineral oil base
 Mixture of grease and graphite
 Mixture of plumbago and axle oil in proportion 4:1

47. 7. Head hardened rails
 Used in advanced railway systems
 Increases life time by 2 to 3 folds
 Hardening is done at iso thermal treatment plant
 A depth of 12 to 14mm from top is hardened
 Heat results in improvement of following
characteristics
 Impact strength 100%
 Relative elongation 50%
 Ultimate strength 50%
 Yield point 75%

48. Measuring wear of rails
 Weighing the worn out rail
 Rail is removed, weighed and fixed after knowing
the wear
 Max. limit is 5%
 If lost more than 10%, should not be used anywhere
on track
 Drawing profile of rail
 Comparison of profile of new rail and old rail to
check the wearing

49. Renewal of rails
 After expiry rails are renewed
 Factors affecting renewal of rails
 Wear of rails
 Max 5%
 Use of heavier locomotives
 Construction of branch lines
 New rails for main track, older ones for branch line
 Bending of rails

50. Rail failures - Reasons
 Sometimes rails fail suddenly without any notice.
Factors that influence the failure are as follows.
 Axle load of locomotive
 Constant reversal of stresses
 Defects in manufacture
 Design of rail joints
 Fatigue caused by shearing stresses
 Frequency of rail renewal
 Maintenance of rail joints

51.  Rail length
 Rail quality
 Rail section
 Rail welding
 Speed of trains etc.,
 The above are some of the main reasons of the
rail failure

52. Rail failures - Types
1. Crushed head
2. Transverse fissure
3. Split head
4. Horizontal fissure
5. Square of angular breaks

53.  Crushed head
 Head gets crushed, metal flows on the head of rail
 Defects in manufacture, flat spots on wheels, slipping of
wheels, week support at the rail end etc.,
 Skidding causes flat spots, loose fish bolts cause week
support at ends
 Transverse fissure
 Fissure or hole in the head
 In the form of a cross wire crack starts inside head and
spreads gradually
 Poor manufacture, excessive straining
 Very dangerous, rail breaks with out any sign often

54.  Split head
 Head is split into 2 parts
 If the surface of crack appears smooth and dark, it is
called as piped rail
 Formed due to cavity during manufacture, or shrinkage
of metal
 Horizontal fissure
 A fissure developed keeps on increasing
 Outcome of worn fish plates or insufficient ballast
 Square or angular breaks
 Rail breaks either in vertical plane or angular plane

55. Coning of Wheels
 Flanges of wheels are never made flat
 Present in the shape of cone with a slope of 1 in 20.
 When wheel are moving on track there is a chance
of lateral movement
 Without coning it will cause a sudden impact on the
sides of rails
 Coning of wheels is mainly done to maintain the
vehicle in the central position w.r.t to the track

56. Coning of Wheels

57. Coning of wheels -
Disadvantages
 Smooth riding possible, but the pressure on the
inner edge may cause its wearing
 Gauge widening happens some times
 If base plates are not provided sleepers under
outer rails may damage
 To minimize these effects, tilting of rails is done
by the use of inclined base plates
 Proper gauge
 Wear is uniform on head
 Increased life of sleepers

58. Creep of rails
 Longitudinal movement of rails in a track is
termed as creep
 Common to all railway tracks
 Value changes from 0 to 130mm per month

59. Creep - causes
 Brakes
 Due to forces while starting or stopping
 Starting – rails pushed backward
 Stopping – rails pushed forward
 Wave motion of wheels
 Due to wheel loads rails deflect as continuous beam
 Crests at supports (i.e., sleepers)
 Changes in temperature
 Unequal expansion and contraction
 Happens more during hot weather

60. Creep on rails

61. Creep - causes
 Following are some of the minor causes
 rails not tightly fixed
 Bad quality sleepers
 Bad drainage
 No proper consolidation of the bed of track
 Gauge maintained tight
 Improper super elevation at curves
 Over capacity of traffic on rails
 Bad joints due to poor maintenance

62.  Allowance of rail expansion joints
 Decaying sleepers
 Uneven spacing of sleepers
 Defective packing
 Insufficient ballast
 Improper usage of brakes

63. Factors determining the magnitude of
creep
 Alignment of track
 Greater on the curves
 Gradient of track
 More on down gradient
 Direction of motion of trains
 One way or 2 way, no of lanes, load of trains
 Embankments
 Creep more on newly constructed embankments
 Weight and type of rail
 Light weight rails creep more than heavy weight
rails

64. Results of creep
 Sleepers move out of
position
 Gauge disturbance
 Gap variation at joints and
other parts, results in
uneven stresses
 Points and crossings will be
disturbed
 Difficult to refix rail with
creep
 Interlocking mechanism
also gets disturbed

65. Measurement of creep
 Measured using creep indicator
 On the side of bottom flange of rail on either sides,
a mark is made by chisel
 Two posts of rail are driven in the formation and
their tops are in level with top of sleeper
 String fastened to the post and passed through
markings towards rail
 Distance between string and the marks on the
bottom of rails will indicate creep during a course of
time

66. Creep measurement

67. Methods for correcting creep
 Pulling back of rails method
 Rails are pulled back equal to the amount of creep
 Manually or using jacks
 Sleeper fittings are made loose, fish bolts are removed
at one end while at the other end are made loose
 At the other end a liner is placed and the rail is pushed
or pulled as required
 Following points should be noted
 Track should be packed properly after pushing/pulling
 Facility should be there to avoid restrictions to existing traffic
 Labour should be procured
 All fish plates, bolts should be cleaned, oiled and refixed
 Good to adjust creep before summer

68.  Usage of Creep anchors
 Pulling back method is tedious, costly
 75% decreased using creep anchor
 Creep anchor is a cast iron piece which is made to
grip the rail
 The arrangement of anchors prevent the movement
of rails there by creep, because the sleepers which
are embedded in the ballast should move for
movement to take place

69. Methods for correcting creep
 Different types of anchors are available
 Following points should be kept in mind while using
creep anchors
 Creep anchor should be strong enough to resist stresses
 No of anchors are determined by the intensity of creep. 4
anchors per rail are provided for a creep of 7.5 to 15cm
 Creep anchors should be placed at points where the creep
originates
 Should be avoided on railway bridges

70. Methods for correcting creep
 Additional creep anchors should be provided on
level crossings, at places where heavy brake
applications are made
 Defective creep anchors should be replaced
 Anchors fixed to rails by using clamping, wedging
and other methods
 Creep anchors should be fixed to good and sound
sleepers

71. Methods for correcting creep
 Use of steel sleepers
 Use of steel sleepers on a track minimizes creep
 Sleepers are provided with fittings which do not
easily allow the creep to occur
 They will also have a good grip with ballast to resist
their movement in ballast
 Increase in number of sleepers will also help in
prevention of sleep.

72. Rail joints
 Joints are made between 2 rails
 Forms the weakest part

73. Characteristics of Ideal Joint
 Rail joint should hold the two ends of the rails as
nearly as possible. The two ends should be at the
same level and in the same straight line.
 Rail joint should have same strength and stiffness
as rails which it joins
 Joint should provide space for the expansion and
contraction of rails
 Joint should be such that any rail can be taken
out easily or disconnected without disconnecting
entire track
 Fishplates, rail contact surfaces wear gradually.
Joints should be able to cope up with this
adjustment.

74.  Ideal joint should be cheap and economical for
setting up and maintenance.
 It should be durable
 Should provide sufficient elasticity so that
vibrations and shocks can be absorbed.
 It should provide resistance to longitudinal forces
developed due to acceleration, deceleration to
reduce creeping effect.
 Joints should be universal type so that they can
be used for all type of sleepers.

75. Avoidance of joints
 In order to obtain better and smooth running of
trains joints are avoided at the following
situations.
 Bridge spans of 6m and below
 Level crossings
 Within 3m of approach of the bridge abutment

76. Types of Rail Joints
 Types according to position of joints
 Square joints
 Staggered joints
 Types according to position of sleepers
 Suspended joints
 Supported joints
 Bridge joints

77.  Square joints
 When a joint in one rail is exactly opposite to the
joint in the parallel rail it is called as square joint.
 Very common type of joint in straight track.
 Also most preferred.
 Staggered joints
 When a joint in one rail is exactly opposite to the
center of the parallel rail length it is called as
staggered joint.

78.  Advantages of staggered joints
 Centrifugal force has a tendency to push the track
out of line. Since the joints are weakest points they
are more vulnerable. But staggered joints resist
them to a great extent.
 More uniform vertical continuity of the track is
formed
 Produce more smooth running than square joints
 Possibility of forming kinks will be decreases

79.  Decreases the vertical disturbance of wheels
 Number of impacts at joints are doubled but
intensity is halved
 Number sleepers per rail length will be increased by
one.
 Staggered joints are more adopted on sharp
curves and not favoured on straight track.
 It is not a rigid rule to fix the rail exactly at the
center.

80. Suspended Joints
 The rail joint when placed at the center of 2
consecutive sleepers is known as suspended
joint.
 Load is equally distributed on sleepers
 When the joint is pressed down both the rail ends
are pressed down evenly.
 More commonly adopted
 Provide greater elasticity to the track
 Cause less disturbance to the wave motion of track
 Require more maintenance

81. Supported Joints
 Sleeper is placed exactly below the joint
 It appears like rails are supported at weakest part.
 These are not used at present
 Supported joint did not give sufficient support to the
heavy axle loads
 If the joint is packed too hard it prevents it from
settling at times
 It leads to the battering of rails as wave motion is
not carried uniformly.

82. Bridge joints
 It is similar to suspended joint.
 Difference is here, a sufficient length of metal is
used to connect the ends of 2 rails, so that there
is no bending stress in the rail.
 Bridge is placed at bottom of rails and rests on
sleepers
 Sleepers at the end will have to be notched out at
the sides or will have to be placed at a lower level
than other sleepers to accommodate bridge.

83. Bridge joints
 The end sleepers are supposed to work as
unyielding fixed supports.
 But practically they are not working as fixed
unyielding supports.
 As a compromise between supported and bridge
joints Indian railways provide semi-supported joints.
 Sleepers at rail joints are bought close here in this
case.

84. Requirements of ideal fastening
 Good fastening connecting rail and sleeper plays
a vital role in improving the efficiency of railway
track.
 Following are some of the requirements of ideal
fastenings.
 Capable of absorbing shocks and vibrations
 Capable of giving protection to the sleeper against
different forces
 Provide insulation in case of electrified tracks

85. Requirements of ideal fastening
 Capable of resisting the creep
 Capable of securing the correct gauge
 Should be economical
 Consist minimum equipment
 Should be durable
 Should be easy to fix and adjust
 Should be non corrosive
 Should have sufficient strength to resist damage
due to derailment

86. Requirements of ideal fastening
 Should be possible to remove only using special
tools
 Should safe guard the alignment in all aspects
 Should not adversely affect the rail and sleepers
 Should not be too rigid
 Adequate strength to resist lateral forces
 Should possess high torque resistance

87. Fastening for rails
 Following are the fastenings which are used to
keep the rails in their correct position.
 Fish plates
 Spikes, fang-bolts and hook-bolts
 Chairs and keys
 Bearing plates

88. Fish plates
 Purpose: connecting the rails at the ends
 Holes are drilled through web and rails and fish
bolts, nuts are provided in these holes.
 When bolts, nuts are tightened it forms a
continuous track
 Design: The pair of fish plates should have the
same strength in bending as the original rail. This
can be achieved by improving section of fish plate
or by using high tension steels.
 For details, types and failures: refer text book

89. Spikes, fang-bolts, hook-bolts
 Purpose: Spikes are required to hold the rails to
the wooden sleepers.
 Dog spikes
 Screw spikes
 Round spikes
 Elastic spikes

90. Chairs and keys
 For double headed and bull headed rails chairs
are required to hold them in position.
 These are made of cast iron and help in
distributing the load from rails to sleepers.
 Chairs are fixed with sleepers by means of
spikes.
 Keys are required to keep the rail in proper
position.

91. Welding of rails
 To join two rails and thus increase the length of
rail
 To repair the worn out or damaged rails and thus
increase their life
 To built up the damaged components of points
and crossings

92. Advantages of Welding
 Increases the life of rails due to decrease in wear
at ends
 Decrease in maintenance cost to 25%
 Smooth functioning of track
 Decrease in creep
 Welded rails better for electrified tracks
 Better for large bridges as rails of length equal to
each span give better performance and reduce
the effect of impact

93.  Welding of rails result in decrease in construction
cost due to less number of joints
 Fast and heavy traffic can be permitted on the
track
 Tractive effort is reduced due to elimination of
energy losses at joints
 Risks of sabotages and accidents are reduced
 More stability in lateral, longitudinal, vertical
directions of track

94. Welding of Rails
 Welding methods
 Gas pressure welding
 Electric arc welding/Metal arc welding
 Flash butt welding
 Thermit welding
 Looking at the advantages, requirements and
facilities available one of the methods is chosen.

95. Gas Pressure Welding
 2 different types of gases – oxygen, acetylene
 Kept in 2 different cylinders
 Burned at 1200C temperature
 Metal rails butted together and welding done.
 Metal flows from rails to form a single section
 Cheaper, good quality but limited outputs

96. Electric Arc Welding
 2 rails are treated as 2 different terminals.
 Electric current is passed across the gap of
butted rails using different techniques.
 Insert plate technique
 Scheron process
 Enclosed space technique
 Current produces heat to melt the electrode kept
in the gap
 Electrode will have same metal composition as
rail
 This method can also be used for repair works

97. Comparison of flash butt and thermit
welding
Flash butt welding
Chemical/Thermit
welding
 Principle of welding:
passing 35000 amp of
electric current
 Quality of weld:
excellent
 Strength of weld:
good in fatigue
 Time required: 3 – 6
mins
 Exothermic chemical
reaction between fe
2O3 and Al at a temp
of 2450C
 Good
 Weak in fatigue
 10 – 12 mins/ 30-
45mins conventional

98. Comparison of flash butt and thermit
welding
Flash butt welding Thermit welding
 Place of welding:
workshop/site
 Cost of welding: less
 Tolerances: Very tight
 Control on quality:
controlled using
welding recorder
 At site
 High
 Normal
 No monitoring
possible

99. Sleepers
and
Ballast

100. Sleepers
 Functions : in a railway track sleepers add to the
stability of the pavement. Following are the
functions.
 Supports the rails firmly
 Maintains the uniform gauge on track
 Distributes the weight coming on the rails over a
sufficiently large area of ballast
 Acts as an elastic medium between rails and ballast
to absorb vibrations of trains
 Provides for easy replacement of rail fastenings
without disturbing traffic

101. Sleepers
 Functions…contd.
 Permits insulation of track for electrified sections
 Maintain the track at proper grade by allowing
raising of the rails and tamping the required quantity
of ballast
 To maintain the alignment of track
 Transfers the load from rails to ballast

102. Requirement of sleepers
 Following are the requirement of good sleepers
 They should maintain correct gauge
 Rails should be easily fixed and taken out from the
sleepers without moving them
 Sleepers should provide sufficient bearing area for
the rail
 Sleepers should provide sufficient weight for the
stability
 They should be sufficiently strong to act as a beam
under loads
 They should provide sufficient effective bearing
area on the ballast
 They should not be pushed out easily of their

103. Requirement of sleepers…contd..
 Design should be such that packing and tamping
should not damage them
 Should be economical in initial as well as in
maintenance cost
 Fittings of the sleepers should be such that rails can
be easily adjusted during maintenance operations
 If track circuiting is required, it should be possible to
insulate them from rails
 They should be able to bear the stresses
 Should not be too heavy, nor too light
 Design and spacing should be such that ballast
packing can be done easily and effectively in less
time.

104. Types of Sleepers
 Depending upon the position in a railway
track, the sleepers may be classified as
follows
 Longitudinal sleepers
 Transverse sleepers
 Timber or Wooden sleepers
 Steel sleepers
 Cast iron sleepers
 Concrete sleepers

105. Longitudinal sleepers
 Early form of sleepers
 Consisted of slabs of stones or pieces of timber
placed parallel to rails
 Cross pieces were provided at intervals to
maintain the correct gauge of track
 At present these sleepers are not in use because,
 Running of train not smooth
 Cost is more
 More noise is created
 Etc.,

106. Transverse sleepers
 Also called as cross-sleepers
 First introduced in UK in year 1835
 Highly popular, and most used in railways at
present
 Most of the disadvantages of longitudinal
sleepers are taken care
 Depending on the type of material used for
manufacturing these sleepers, classified into
different types:
 Timber sleepers
 Steel sleepers
 Cast iron sleepers
 Concrete sleepers

107. Timber sleepers
 Also called as wooden sleepers
 Fulfils most of the requirements of ideal sleeper
 Used universally
 Teak wood is considered as best
 But due to high cost, mainly used as sleepers for
girder bridges
 Salwood, Deodar, fir and chirwood are used as
alternatives where those are easily available
 At present usage and manufacturing decreased
because of the advent of new type of sleepers

108. Timber Sleepers - Features
 Utility:
 Very much useful for heavy loads and high speeds
 Life:
 Depends on various factors such as climatic
conditions, intensity and nature of traffic, quality of
wood, method of packing, type of fastening,
protection against mechanical wear etc.,
 Treatment:
 Liable to be attacked by vermins hence treatment
required to have more resistance.
 Preservatives are used for this purpose.
 Solutions used for timber sleepers are zinc chloride,
creosote solution, salt solution or bi chloride of
mercury salt.

109. Timber sleepers - Features
 The methods of zinc chloride solution and mercury
salt solutions are known as burnettising and
kyanizing respectively.
 Some times sleepers are just painted.
 Corrosion:
 Not corroded
 Insulation:
 Ideal for track circuited section as they are good
insulators
 Size:
 Depends on the load coming and quality of wood.
 Depending on the treatment i.e., treated or not, size
of wooden sleepers are standardized by Indian
railways.

110.  However, longer
sleepers upto length
488cm are used for
bridges with open
flooring, points and
crossings.
 Section of sleepers is
also increased by
300x160mm.
 Rectangular, half
round shapes are
used often.

111. Timber sleepers - Features
 Driving of spikes:
 spikes should be driven carefully through the
sleeper
 Else damaged, gauge will be disturbed
 Name and year:
 Name of wood used and year of laying the sleepers
is normally marked on the top surface of sleeper.
 Normally nails with letters and markings were used
before but not used these days
 Adzing:
 Wooden sleepers are adzed or cut at rail seat to get
a slope of 1 in 20 when un canted bearing plates
are used.

112. Timber sleepers - Features
 Adzed surface will be treated normally with tar or
creosote
 Improper adzing leads to uneven surface for the
rails.
 Further creeping and other types of damage will
occur
 Storage:
 Large area exposed to air and ventilation is
normally used
 Care will be taken so that sun do not fall directly on
the sleepers
 Stack is some times covered with earth to prevent
fire accidents

113. Timber Sleepers as Bridge
sleepers
 Thicker than standard sleepers. Minimum depth
of sleepers without fastenings should be 150, 125
and 125 mm for BG, MG and NG respectively
 Length of sleepers is D+30 cm. D is out side
distance between edges of parallel girders
 Should not be adzed
 Necessary to provide bearing plates
 Should be placed sufficiently close to prevent the
wheels of derailed train falling through the space
between the adjacent sleepers. Max space is 50,
30, 25 cm for BG, MG and NG respectively.

114. Composite Sleeper Index (CSI)
 Forest research institute, Dehradun arrived at a
formula taking different strength parameters into
account for the use of timber for sleepers
 An index number is worked out using this formula
with which we can identify whether a timber can
be used or not for sleeper
 Chir – 54
 Deodar – 63
 Fir – 58
 Sal – 112
 Teak - 82

115. Composite Sleeper Index (CSI)
 Minimum CSI values for different sleepers are as
follows
 Bridge sleepers – 1455
 Crossing sleepers – 1352
 Track sleepers –783
 Bearing plates are used in case timber has a CSI
value less than 82.
 CSI = (S+10H)/20
 S = strength index of timber at 12% moisture
 H = Hardness index of timber at 12% moisture

116. Timber Sleepers - Advantages
 Less no of fittings
 Simplistic design
 Suitable for all types of ballast
 Easy to lay, relay, pack, lift and maintain
 Less noisy track
 Economical overall
 Obtained in different sized and lengths for easy
adoptability at certain locations viz., bridges,
crossings etc

117.  Permits track circuiting
 Damage during derailments is less
 Can be placed on yielding formations because of
more bearing area
 Possible to widen the gauge easily with wooden
sleepers

118. Timber Sleepers - Disadvantages
 Difficult to maintain gauge
 High maintenance cost
 Less useful period
 Easily disturbed from their positions
 Easily subjected to wear and decay due to
various forces and causes
 Require special treatment for protection
 Possess less scrap value

119. Steel Sleepers
 Extensively used in Indian railways
 Consist of steel troughs made of 6mm thick steel
sheets
 Both ends bent down to check the running out of
ballast
 2 types
 1. Jaws or lugs pressed out of metal and keys are
used for holding the rail. At the time of pressing cant
of 1 in 20 is also provided for the rails
 2. holes are made in the sleepers and clips, bolts are
used for fixing the rail.
 For fixing the rails, first rails are inserted into the
lugs and wedges/keys are fixed on both sides of
rails. Gauge can be adjusted with the help of keys.

120. Steel Sleepers

121. Steel Sleepers - Characteristics
 Life:
 Useful life of steel sleepers is taken as 30 to 40
years on a normal route
 On high density traffic routes it can be taken as
about 20 years
 Track provide with steel sleepers doesn’t require
much attention as renewal is not frequent.
 Corrosion:
 Steel sleepers not liable to be attacked by vermins
 But easily corroded due to moisture. Hence,
treatment is done to protect against corrosion.

122. Steel Sleepers - Characteristics
 Insulation:
 Cannot be used in electrification of track. As they
are not good insulators.
 Details:
 Consist of a trough or channel made of steel plate
about 6mm thick.
 Ends bent down to prevent running of ballast
 Rails are fixed with steel sleepers by the help of
keys to the pressed up lugs.

123. Steel Sleepers - Requirements
 Should be possible to fix the rails easily in
sleepers with out disturbing the sleepers
 Should be possible to insulate them easily incase
at place where track circuiting exists.
 Rail should have enough bearing area
 Thickness and shape should be such that they
will be strong as beams
 Capable of maintaining correct gauge
 Should be designed in such a way that tamping
or packing should not damage the edges

124. Steel Sleepers - Requirements
 Should be sufficiently heavy for the purpose of
stability
 Should have effective bearing area on the ballast
 Should not be capable of being easily pushed out
of position.
 Etc.,

125. Steel Sleepers - Advantages
 Less fastenings, simple in nature
 Maintenance and adjustment of gauge are easy with
steel sleepers
 Manufacturing process of steel sleepers is simple in
design and operation
 Are available in one piece
 Possess good scrap value
 Light in weight, easy handling
 Meets requirement of long welded track in cases
 Good anti creep sleeper
 Behaves better in the case of yielding formation.

126. Steel Sleepers - Disadvantages
 Cost of steel sleepers is high
 Cracks develop at rail seat
 Rounded ends of sleepers prevent lateral shift
 Liable to corrosion
 Are not good insulators
 Excess damage during derailment
 Steel sleepers are difficult to pack at the rail joints
because of their close spacing.
 Leads to battering of rails

127. Cast-iron sleepers
 Were adopted on indian railways since 1870
 More than 50 % of the sleepers are made of cast
iron as of 2000
 They are generally of the following types
 Pot sleepers
 Plate sleepers
 Box sleepers
 C.S.T.- 9 sleepers
 Duplex sleepers

128.  Pot sleepers are in the form of two bowls placed
under each rail and connected together by a tie-
bar
 Total effective area of the both pot sleepers is
kept 0.46sq.m which is equal to effective bearing
area of a wooden sleeper.
 Two holes are provided under each sleeper for
inspection and packing ballast
 And the rail seat is given a slope of 1 in 20.
 Both the pots are connected together with a tie
bar with necessary fittings such as keys, gibs and
cotters.

129.  Plate sleepers consist of a plate of 851x254mm in
dimensions, with 254mm side parallel to the rails.
 Both sleepers provide an effective bearing area of
0.46sq.m under each rail.
 Plate is provided with projecting rib in the bottom
to provide a grip in the ballast to check the lateral
movement of sleeper.
 At the top plate stiffeners are provided to increase
the strength.
 Sleeper plates are connected by means of a tie
rod.

130.  C.S.T. – 9 Sleepers: These are more satisfactory
than other type of CI sleepers.
 It is actually a combination of plate, pot and box
sleeper.
 It essentially consists of a triangular inverted pot
on either side of the rail seat.
 Suitable rail seat or rail chair is provided at the
top to hold rails at 1 in 20 cant.
 Two pieces of sleeper are connected by means of
a tie rod.

131. Cast-iron sleepers -
characteristics
 Details:
 C.I sleepers consists of 2 pots or plates with ribs
below and connected by a wrought iron tie bar of
section of about 51x13mm.
 Each pot or plate is placed below each rail.
 Shape of pot or plate is used to be circular prior. But
present, oval shape with larger diameter 610mm
and smaller diameter 508mm is preferred.
 Each pot is provided with holes for packing ballast
and inspection.
 Plate sleepers consist of rectangular plates of size
about 864x305mm.
 The projecting ribs are kept below for their lateral
stability.
 Tie bars can be fixed by keys, gibs, cotters and

132. Cast-iron sleepers -
characteristics
 Scrap value:
 Possess considerable scrap value. Broken pots and
plates can be melted and reused for preparing new
pots and plates.
 Maintenance of gauge:
 In case of CI sleepers there is no rigid connection
between 2 separate supports. Hence difficult to
maintain the correct gauge.
 Fittings:
 The cast iron sleepers require a large number of
fittings than any other type of sleepers.

133. Cast-iron sleepers -
characteristics
 Handling:
 The C.I. Sleepers are liable to be broken and
seriously damaged, if roughly handled.
 Life:
 The usual life of C.I. Sleepers may be taken as 35
to 50 years in normal routes.
 15 to 20 years in heavy traffic routes.
 The service life can be increased by proper packing
, clean ballast, providing coal tar to tie-bar etc.

134. Cast-iron sleepers - Advantages
 It can be easily dismantled and assembled.
Hence, transport is easy even though it is heavy.
 Can tolerate certain amount of rough handling.
 Possess high scrap value
 Good longitudinal and lateral resistance
 Shape is well suited for ballast packing and skill
required for its maintenance is minimum
 Adjustment in gauge can be done ( about 5mm)
with help of cotters in case if it is needed.
 Sleeper is not affected by the random or irregular
dropping of fire by the steam engines.

135. Cast-iron sleepers -
Disadvantages
 During derailment damage is excessive and it
requires more time for restoration.
 Not suitable for circuiting of track.
 Leads to early wear of sleeper because of small
bearing area at the rail seat.
 Not suitable for modern methods of maintenance
 Possess poor ability to retain the packing due to its
rigid fastenings.
 It takes about 6 months for proper consolidation after
complete track renewal and sleeper renewal.
 When these sleepers are used, rails have longer
unsupported length and may therefore lead to
battering of rails.

136. Concrete Sleepers -
characteristics
 Type:
 Can be made of R.C.C or pre-stressed concrete.
 Weight:
 Weight of concrete sleepers varies from 150 to
300kg which is more than wooden or metal
sleepers.
 This provides more stability to track.
 Life:
 Good durability
 Useful life of about 30 to 25 years on high density
routes

137. Concrete sleepers -
characteristics
 Suitability:
 Most suitable for welded tracks
 Dead weight of entire track assembly including
sleepers play an important role in the design of
welded rail track.
 Since, weight is more they perform better under
welded rails
 Fastenings:
 Should firmly hold the rail to resist creep
 Should be easily dis-engaged and re-engaged
 Different types of fastening equipment is available
for concrete sleepers.
 Ideal fastenings for sleepers and rails will differ
according to the type of track, type of traffic and the
climatic conditions.

138. Concrete sleepers -
characteristics
 Special PSC sleepers have been developed to
meet with the special requirement of different
locations such as sharp curves, level crossings
with facilities for providing check rails, guard rails
etc.,
 Mass production:
 Mass production techniques are to be adopted for
the design and manufacture of sleepers.
 Economical production of concrete of high strength,
handling of sleepers, good plant design, accelerated
hardening of sleepers etc., have to be taken care
off.
 Initial cost of concrete sleepers will be very high, but
maintenance and other things will be economical
because of long life.

139. Concrete sleepers -
characteristics
 Environmental protection:
 These PSC sleepers are environmental friendly.
 Conserves forest.
 Structural advantages:
 Have lot of structural advantages
 Center to center distance can be increased by 20%
compared to timber sleepers
 Deflection under loading is much less
 Improves lateral, longitudinal and vertical stability
 Reduced bending stresses, reduced wear of rolling
track, less chance of derailment, reduction in tractive
effort etc.

140. Concrete sleepers - Advantages
 High electrical resistance
 Good resistance to abrasion
 Increased bond resulting in shorter transmission
length.
 Increased impermeability
 Reduction in loss of pre-stress due to reduction in
shrinkage, creep and elastic shortening
 Very high fatigue strength.

141. Concrete sleepers - Drawbacks
 The damage during derailment is excessive
 Possess no scrap value
 Require complete machanisation in handling
 Requires use of superior and costly technology
for manufacture.

142. Sleeper Density
 No of sleepers present in a given length of rail
 Spacing of sleepers is indicated by formula n+x
 n = length of rail
 x = no of sleepers more than n.
 Sleepers density depends on several factors:
 Lateral thrust of locomotives to which the track is
subjected
 Axle –load which the track is expected to carry
 Sleepers density cannot be increased indefinitely
– minimum spacing is required for packing ballast
and maintenance.
 Wooden sleepers 300mm (for BG), 250mm (for
MG)
 Metal sleepers 380mm (for BG), 330mm (for MG)

143. Sleeper density
 In case of staggered joints an extra sleeper is
required
 Sleepers are placed nearer at rail joints
compared to other locations.
 In n+x expression, x value is fixed by indian
railway considering the following:
 Axle load and speed
 Type of ballast and ballast cushion
 Type and section of rails
 Type of sleeper and its bearing area on the ballast.

144. Ballast
 Material placed between the sleeper and top of
the formation is known as ballast.
 Load from the wheels will be taken up by the
ballast through rails and sleepers.
 Ballast serves as foundation of railway track and
is present just below the sleepers.

145. Ballast - Functions
 To provide a hard and smooth surface for the
ballast to rest on
 Hold the sleepers in place during the passage of
trains
 To transmit and distribute the load from sleepers
to formation
 Allow for maintaining correct track levels without
disturbing the rail road bed.
 Protect the surface of formation from direct
exposure to sun, frost or rain.
 To form an elastic bed

146. Ballast - Functions
 To drain the water immediately and keep the
sleepers in dry condition
 To discourage the growth of vegetation
 To resist lateral, longitudinal and vertical
displacement of track.

147. Requirements of ideal material for
ballast
 Should be possible to main uniform depth of material
for uniformly distributing the load to formation
 Should provide sufficient grip over the sleepers to
prevent their movement
 Ballast should not be too rigid, it should be elastic in
nature.
 Material of ballast should not be brittle, should
possess required compressive strength.
 Should provide good drainage facility.
 Should be cheap and easily available.
 Should not have any chemical action on rail and metal
sleepers
 Should be durable and abrasion resistant

148. Ballast Materials
 Broken stone
 Gravel
 Ashes or cinders
 Sand
 Kankar
 Moorum
 Brickbats
 Selected earth

149. Broken stone
 One of the best material, but expensive.
 Many important tracks are having stone ballast
 Possesses all characteristics of good ballast
 It has good interlocking characteristics, due to
that it holds track in correct alignment and
gradient
 It is resistant to abrasion, provides good
drainage.
 Stones which are non-porous, hard and tough
should be used as ballast
 Granite is best material. But quartize, sandstone,
limestone are also used.

150. Gravel
 It is next best material after broken stone. It consists
of smooth rounded fragments obtained from river
beds and other natural deposits.
 Washing should be done for the material obtained
from pits
 Uniform and required size of aggregates should be
used.
 Rounded pieces are sometimes broken to improve
interlocking properties.
 Advantages:
 Cheaper than stone ballast
 Good drainage property
 Disadvantages:
 Easily rolls down due to vibration

151. Ashes or Cinders
 The residue from the coal used in locomotives and
other furnaces is known as the ashes or cinders.
 It is by product of railway systems which are run by
coal fuel
 Advantages
 Good drainage properties. Used in yards to keep them
dry
 Handling is easy
 Low cost and easily available.
 Can be used for repairing formation, and packing during
emergency.
 Disadvantages:
 Very soft, easily becomes powder hence track becomes

152. Sand
 Coarse sand is preferred to fine sand
 Not used in main and branch lines. Used only in
some unimportant lines, sidings, yards.
 Advantages:
 If sand is pure, possesses excellent drainage
property
 Produces a silent track
 Cheap and easily available
 Disadvantages:
 Frequent renewal is required
 Disturbed easily by vibrations. More maintenance
required.
 Causes more friction, and leads to abrasion and
wearing.

153. Kankar
 Found in many places
 Suitable only if other types of material is not
available and if the traffic is less on metre gauge
and narrow gauge
 It becomes powder very easily and hence not
prefered
 More maintenance is required if used

154. Moorum
 Decomposition of laterite results in the formation of
moorum
 Present in red/yellow colour
 Used for unimportant lines and sidings
 Advantages:
 Can be safely used on newly laid track. It serves as
soling when the stone ballast is laid afterwards
 Possesses good drainage properties
 Disadvantages:
 Soft and turns into dust very easily
 Maintenance is very difficult

155. Brick bats
 Over burnt bricks are broken into suitable sizes and
used as ballast
 Advantages:
 Useful at places where suitable material is not
available
 Good drainage properties
 Disadvantages:
 Turns into powder form very easily
 Track becomes dusty and high maintenance is
required.
 Rails are often corrugated on tracks where brick bats
are used as ballast

156. Selected earth
 For sidings and newly constructed tracks,
selected earth of suitable quantity is sometimes
used as ballast
 The main purpose of using earth on new
formation is to prevent the loss of valuable and
expensive ballast sinking into the soft formation.

157. Specifications of Stone ballast
 Quality:
 Should be durable, hard, resilient to impact and free
from adherent coatings.
 Should not contain more than 10% by weight of quarry
dust, rubbish or any other matter which passes
through 5mm sieve
 Faces of ballast should result from crushing, only one
smooth surface is allowed
 Size:
 20 to 50mm size with reasonable proportion of
intermediate sizes.
 50mm – wooden and CI spot sleepers
 40mm – CST -9 sleepers

158. Specifications of
stone ballast
 grading:
 Ballast should be well graded
 Sampling:
 Sample of ballast is collected
at the rate of 1cu.m per 2000cu.m.
 Over sized ballast:
 When more than 10% of ballast retains on nominal
size sieve it is called over sized ballast
 Stacking:
 Ballast should be stacked along the quarry siding.
 Height of stack should not be less than 120cm.

159. Depth of Ballast Section
 Depth of ballast section can be calculated by
using the below formula
 D = (S-b)/2
 Where D – depth of ballast section
 S – sleeper spacing
 b – width of sleeper
 Normally the value ranges in between 20 to 25cm
from the above formula.

160. Section of Ballast

161. Screening of Ballast – Ballast
Renewal
 Ballast used on the railway track is to be
renewed from time to time due to following
reasons
 Ballast gets powdered due to hammering of
wheels. Fills voids in the ballast layer
forming impermeability.
 Ballast gets pressed into formation.
Available ballast quantity gets reduced with
time. Elasticity will also gets disturbed.
 To avoid and remove all these effects ballast
is cleaned at regular intervals by means of
screening.

162. Process of screening
 Surface will be normally clean. Hence ballast
forks are used for cleaning.
 Dirty ballast is made loose by means of
equipment such as picks.
 Frames of size 150x120cm with expanded metal
mesh are put parallel to the track.
 Dirty ballast thrown on to the mesh to separate
the dirt and aggregate ballast.
 Required quantity of additional ballast is added to
screened ballast to make up the deficiency.