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Railway Engineering:
Component Parts Of A Permanent Way
Following are the components of a permanent way
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Sleepers are properly placed and packed
with ballast
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Requirements of An Ideal Permanent Way
Following are the basic requirements of a permanent way:
(i) The gauge should be uniform and correct
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(iii) On curves proper super elevation should be provided to the outer rail
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(v) The track should have enough lateral strength
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(vii) The track must have certain amount of elasticity
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(ix) Drainage system of permanent way should be perfect
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(xi) It should have adequate provision for easy renewals and repairs
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Double headed rails (D
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Rails)
2
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H
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Flat footed rails (F
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Rails)
Double Headed Rails
The rail sections, whose foot and head are of same dimensions, are called Double
headed or Dumb-bell rails
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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
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This type of rail is not in use in Indian Railways now-a days
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In this type of rail the head is made little thicker and stronger than the lower part
by adding more metal to it
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Bull
headed rails are especially used for making points and crossings
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H
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(ii) These rails provide longer life to wooden sleepers and greater stability to the track
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Demerits
(i) B
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rails require additional cost of iron chairs
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(iii) B
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rails are of less strength and stiffness
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This type of rail was invented by Charles Vignole in 1836
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H
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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
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These rails are
most commonly used in India
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F
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(ii) No chairs are required for holding them in position
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(iv) The maintenance cost of track formed with F
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rails is less
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(ii) These rails are not easily removed and hence renewal of track becomes difficult
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SLEEPERS
Sleepers are transverse members of the track placed below the rails to support and fix them in
position
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(ii) To transfer the loads from rails to the ballast
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(iv) To keep the rails at a proper level in straight tracks and at proper super elevation on
curves
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(vi) To provide stability to the permanent way on the whole
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(ii) The sleepers should be economical
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(iv) They should provide sufficient bearing area for the rail
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(vi) Sleepers should facilitate easy fixing and taking out of rails without disturbing them
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(viii) They should not be pushed out easily of their position in any direction under maximum
forces of the moving trains
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(x) They should be suitable to each type of ballast
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Types of Sleepers
Sleepers are of the following types:
1
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2
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3
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4
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C
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sleepers
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Priestesses concrete sleepers
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Wooden Sleepers: These sleepers are regarded to be the best as they satisfy all the
requirements of good sleepers and are the only sleeper suitable for track circuiting
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Timbers commonly used in India for sleepers are sal, Teak, Deodar and chair
wood
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G
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G
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G
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(ii) Wooden sleepers are suitable for all types of ballest
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(iv) These sleepers give less noisy track
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(vi) These sleepers are best suited for track circuiting
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(ii) It is difficult to maintain guage of the track in case of wooden sleepers
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(iv) Track laid over wooden sleepers is easily disturbed
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2
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At the time of pressing of
sleepers, an inward slope of 1 in 20 on either side is provided to achieve required tilt of rails
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Steel sleepers are of two types:
(a Key type steel sleepers
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(a) Key type steel sleepers: In this type of sleepers lugs or jaws are
Pressed out of metal and keys are used for holding the rails
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Fig
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2 shows key type steel sleepers
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5
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Cracks are not developed in the sleepers as the holes for
the bolts are small and circular
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Advantages
(i) Steel sleepers are light in weight and can be handled easily
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(iii) He life of steel sleepers is more than the wooden sleepers
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(v) The scrap value is more than the wooden sleepers
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(vii) Creep of rails can be checked by using steel sleepers
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(ii) Cracks are developed at rail seat of these sleepers
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(iv) These are not suitable for all types of ballast
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3
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Cast iron sleepers are of the following
types:
(i) Pot or bowl sleeper
(ii) Plate sleeper
(iii) Box sleeper
(iv) CST-9 sleeper
(v) Duplex sleeper
i
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iii
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Pot or bowl sleeper: Pot sleeper consist of two bowls placed under each rail and
connected together by a tie-bar
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464 sq
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Each pot is provided with two holes foe inspection and packing of ballast
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Gibs
and cotters are so casted that by interchanging them gauge is slackened by 3 mm
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The plates are provided with projecting ribs in
the bottom to provide a grip in the ballast for lateral stability
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Stiffners are provided at the top of the plate to increase the
strength
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5
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It
provides the effective bearing area of 0
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m per sleeper
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Box sleepers are similar to
plate sleepers
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CST-9 Sleeper: CST-9 sleeper is more satisfactory than other C
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Sleepers and is
extensively used in Indian Railways since last thirty years
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CST-9s sleeper consists of a triangular inverted pot one on
each side of rail seat
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The pots are connected across the track by means of a tie- bar
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5
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v
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These sleepers are
used at rail joints to prevent cantilever action between two supports of the CST-9
sleepers
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The plates are
placed with the longer side parallel to the rails and are connected with a tie-bar
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I sleepers:
(i) The life of C
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(ii) The maintenance cost of these sleepers is low
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(iv) These sleepers are more durable
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Disadvantages
(i) More ballast is required than any other type of sleepers
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(iii) These sleepers are liable to break
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I
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(v) These are not suitable for all types of ballast
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R
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C
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C
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Sleeper: This is also known as one piece or mono-block sleeper
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These cracks are very
small and almost invisible but tend to enlarge with the repetition of impact loading, causing
failure
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C
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Sleeper: This type of sleeper consists of two R
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C
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These sleepers are not subjected to any degree
of tensile stress as in through type
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C
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Sleepers
(i) Concrete sleepers have long life, generally 40to 60 years
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(iv) These sleepers require less fittings
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(vi) These sleepers provide more lateral and longitudinal rigidity as compared to other
sleepers
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(viii) Due to higher elastic modulus, these can withstand the stresses due to fast moving
trains
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ii
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iv
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Due to heavy weight, handling and transportation of these sleepers are
Difficult
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The renewal of track laid with these sleepers is difficult
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5
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These sleepers have high initial cost but are very cheap in long run due to their long life
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These wires are stretched by hydraulic jack
to give necessary tension in the wires
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These sleepers are heavily damaged in caser of derailment or accidents of
trains
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Functions of Ballast
Ballast in railway track performs the following functions
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(ii) To distribute the axle load uniform from sleepers to a large area of formation
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It acts as as elastic mat between subgrade and sleepers
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(v) To drain rain water from the track
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Characteristics of Good Ballast
(i) It should have sufficient strength to resist crushing under heavy loads of moving trains
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(iii) It should have rough and angular surface so as to provide good lateral and longitudinal
stability to the sleepers
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(v) It should be cheaply available in sufficient quantity near and along the track
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(vii) It should allow for easy and quick drainage of the track
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Types of Ballast
In India, the following materials are used as ballast
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(ii) Gravel
(iii) Sand
(iv) Ashes or cinders
(v) Kankar
(vi) Moorum
(vii) Blast furnace slag
(viii) Brick ballast
(ix) Selected earth
(I)Broken Stone: This is the best type of ballast as it possesses all the characteristics of a
good ballast
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The stones which are non porous, hard and do not flake on breaking should be used
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This type of ballast is
used for high speed tracks
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It is hard and resist crushing under heavy loads
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It has angular and rough surface and hence gives more stability to the sleepers
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Its drainage property is excellent
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(b) It is not so easily available
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This is obtained either from river
beds or from gravel pits and has smooth rounded fragments
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Gravel obtained from river beds
is screened and required size gravel is used
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Round edges gravels are broken to increase their interlocking action
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(b) The drainage property of gravel excellent
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(d) It is east to use gravel ballast than stone ballast at certain places where formation is
unstable
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(b) Gravel obtained from pits requires washing
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(d) Gravel easily roll down due to vibrations
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Coarse sand is generally
preferred to fine sand for ballast
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It is
used only on unimportant tracks
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(b) It is available in large quantities
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(d) Sand ballast produces a silent track
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(b) It causes wear of rail, seats and keys
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Advantages
(a) It is a cheaper ballast material
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(c) It is available in large quantities and hence can be used in emergency
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Disadvantages
(a) It is very soft and gets crumbled to powder under heavy loads
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(v) Kankar: It is natural material in the form of nodules from which lime is prepared
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(b) It has good drainage property
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(b) The track laid on kankar ballast are difficult to maintain
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(vi) Moorum: It is a soft aggregate and is obtained by the decomposition of laterite
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It is used in unimportant lines and sidings
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(b) It has good drainage properties
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Disadvantages
(a) It is soft and easily crumbles to powder under heavy loads
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(vii) Blast Furnance Slag: It is a waste product obtained from the blast furnace of steel
industry
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Advantages
(a) It is a cheap material
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(c) It is a strong material
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Disadvantages
(a) It is not available in large quantity
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(c) Maintenance of track laid on slag ballast is difficult
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Advantages
(a) It is a cheap material
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(c) It has good drainage properties
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(b) The rails laid over such ballast get corrugated
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When tracks are laid on new formation, then sleepers are packed with earth for a few months
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The use of earth ballast in the beginning is to prevent the loss of good ballast by sinking into
soft formation
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FUNCTIONS OF FIXTURES AND FASTENINGS
Rail fixtures and fastenings have the following functions:
(i) To join the rails end to end to form full length of track
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(iii) To maintain the correct alignment of the track
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(v) To maintain the required tilt of rails
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TYPES OF FIXTURES AND FASTENING
Fixtures and fastenings commonly used in a permanent way are of following types:
1
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Bearing plates
3
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Chairs
5
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Keys
7
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Two types of fish
plates are commonly used on Indian Railways for joining F
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and B
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rails, as shown in
Fig
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1
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These are manufactured of steel and are so designed that they fit in between the
head and foot of the rail
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(ii) They should allow free longitudinal movements of rails due to temperature variation
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(iv) They should be able to bear the vertical and lateral stresses which come at joints without
any distortion
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BEARING PLATES
Bearing plates are cast iron or steel plates placed in between the F
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F
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rails if fixed directly on wooden sleepers sink in the sleeper due to the
heavy loads of trains and thus loosen the spikes
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F
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Bearing plates give the required 1 in 20 inward slope to the rail directly and no adzing* is
required in the wooden sleeper
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ADVANTAGES
Following are the advantages of bearing plates:
(i) They distribute the loads to wider area and prevent sinking of the rail to the sleeper
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(iii) They enable the spikes to remain tight and require less maintenance
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(v) Bearing plates increase the overall stability of the track
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DISADVANTAGES
Following are the disadvantages of bearing plates:
(i) When the bearing plates become loose due to settlement of ballast,
moisture is likely to enter between the sleepers and plates, causing
sleepers to wear
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SPIKES
Spikes are used to fix rails to wooden sleepers
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These are commonly used for holding F
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rails
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The disadvantage of dog spikes
is that these become loose under the wave action caused by the moving train
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H
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These have either cylindrical or hemispherical
head and blunt end
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Their head is circular with a square
projection and are used to fasten rails with wooden sleepers
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Elastic spikes are used for fixing F
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rails to wooden sleepers
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The advantage of this type of spike is that it is
not pulled up by the wave action of the moving train
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(ii) It should hold the rails and bearing plates in proper position
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(iv) It should require minimum maintenance
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BOLTS
Different types of bolts used in Indian Railway are described below
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Four bolts are required for each
pair of fish plates
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Fish bolts have to withstand shear due to heavy transverse stresses, hence they are
manufactured of medium or high carbon steel
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For 44
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6 mm length are used
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Too much tightening of bolts is prohibited as it prevents free expansion or
contraction of rails due to temperature vibrations
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These bolts are used
to fix sleepers which rest directly on a girder
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Dog bolts are of
two types
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(ii) Straight lips- for fixing sleepers to joist spans
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These are alternative to screw or round
spikes
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KEYS
These are small tapered pieces of timber or steel used to fix rails to chairs on metal sleepers
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These are cheap and Easily
prepared
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These require frequent
maintenance
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Metal keys are small tapered or spring like pieces of steel
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Metal keys are of two types
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Different shapes of anti-creepers
are available and are fixed to the foot of rail

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