Component Parts Of A Permanent Way-PDF Free Download

COMPONENT PARTS OF A PERMANENT WAY

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COMPONENT PARTS OF A PERMANENT WAY Following are the components of a permanent way. (i) Subgrade (ii) Ballast (iii) Sleepers (iv) Rails (v) Fixture and Fastening In a permanent way, rails are joined either by welding or by using fish plates and are fixed with sleepers by using different types of fastenings. Sleepers are properly placed



RAILWAY ENGINEERING Dept of Civil Engineering KLU
TYPES OF RAILS
The rails used in the construction of railway track are of following types
1 Double headed rails D H Rails
2 Bull headed rails B H Rails
3 Flat footed rails F F Rails
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 Fig
4 1 shows double headed rail
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
i B H Rails keep better alignment and provide more smoother and stronger track
ii These rails provide longer life to wooden sleepers and greater stability to the
iii These rails are easily removed from sleepers and hence renewal of track is easy
i B H rails require additional cost of iron chairs
ii These rails require heavy maintenance cost
iii B H rails are of less strength and stiffness
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
RAILWAY ENGINEERING Dept of Civil Engineering KLU
bearing plates were used in between flat footed rails and the wooden sleeper These rails are
most commonly used in India Fig 4 3 shows flat footed rail
i F F rails have more strength and stiffness
ii No chairs are required for holding them in position
iii These rails require less number of fastenings
iv The maintenance cost of track formed with F F rails is less
i The fittings get loosened more frequently
ii These rails are not easily removed and hence renewal of track becomes
iii It is difficult to manufacture points and crossings by using these rails
RAILWAY ENGINEERING Dept of Civil Engineering KLU
Sleepers are transverse members of the track placed belos the rails to support and fix them in
FUNCTIONS OF SLEEPERS
Sleepers serve the following functions
i To hold the rails to proper gauge
ii To transfer the loads from rails to the ballast
iii To support and fix the rails in proper position
iv To keep the rails at a proper level in straight tracks and at proper super
elevation on curves
v To provide elastic medium between the rails and the ballast
vi To provide stability to the permanent way on the whole
REQUIREMENTS OF GOOD SLEEPERS
The following are the requirements of good sleepers
i The sleepers should be sufficiently strong to act as a beam under loads
ii The sleepers should be economical
iii They should maintain correct guage
iv They should provide sufficient bearing area for the rail
v The sleepers should have sufficient weight for stability
vi Sleepers should facilitate easy fixing and taking out of rails without disturbing
vii They should facilitate easy removal and replacement of ballast
viii They should not be pushed out easily of their position in any direction under
maximum forces of the moving trains
ix They should be able to resist impact and vibrations of moving trains
x They should be suitable to each type of ballast
xi If track circuiting is done it should be possible to insulate them from the rails
TYPES OF SLEEPERS
Sleepers are of the following types
1 Wooden sleepers
2 Steel sleepers
3 Cast iron sleepers
4 R C C sleepers
5 Priestesses concrete sleepers
RAILWAY ENGINEERING Dept of Civil Engineering KLU
1 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
The life of wooden sleepers depends upon their ability to resist wear attack by white ants and
quality of timber used Timbers commonly used in India for sleepers are sal Teak Deodar
and chair wood
The standard sizes of wooden sleepers for different gauges are as follows
For B G 2740 mm X 250 mm X 130 mm
For M G 1830 mm X 203 mm X 114 mm
For N G 1520 mm X 150 mm X 100 mm
ADVANTAGES
i Timber is easily available in all parts of India
ii Wooden sleepers are suitable for all types of ballest
iii Wooden sleepers require less fastening and simple in design
iv These sleepers give less noisy track
v These sleepers absorb shocks and vibrations more than any other sleepers
vi These sleepers are best suited for track circuiting
DISADVANTAGES
i The life of wooden sleeper is less as compared to other types of sleepers
ii It is difficult to maintain guage of the track in case of wooden sleepers
iii These sleepers are subjected to wear decay and attack by white ants etc
iv Track laid over wooden sleepers is easily disturbed
v Maintenance cost is more as compared to other sleepers
2 Steel Sleepers These sleepers consist of steel throughs made of 6 mm thick sheets
with its both ends bend down to check the running out of ballast 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
The standard length of these is 2680 mm Steel sleepers are of two types
a Key type steel sleepers
b Clip and bolt type steel sleepers
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 These are of two types
i Lug type
ii Loose jaw type
RAILWAY ENGINEERING Dept of Civil Engineering KLU
Lugs are formed by pressing out the metal of the channel section loose jaw type is an
improvement on pressed lug type Fig 5 2 shows key type steel sleepers
b Clip and bolt type steel sleepers In this type of sleeper clips and bolts are used for
holding the rails as shown in Fig 5 3 Cracks are not developed in the sleepers as the holes for
the bolts are small and circular It requires four clips and four bolts for holding each rail
ADVANTAGES
i Steel sleepers are light in weight and can be handled easily
ii These require less fastenings
iii He life of steel sleepers is more than the wooden sleepers
iv The gauge can be easily maintained and adjusted
v The scrap value is more than the wooden sleepers
vi The track laid on steel sleepers has good lateral and longitudinal rigidity
vii Creep of rails can be checked by using steel sleepers
DISADVANTAGES
i Initial cost of these sleepers is more than wooden sleepers
ii Cracks are developed at rail seat of these sleepers
iii Steel sleepers are not suitable for track circuiting
iv These are not suitable for all types of ballast
v These are liable to corrosion
3 Caste Iron Sleepers
The sleepers made of cast iron known as cast iron sleepers have been extensively used in
India as compared to other countries in the world Cast iron sleepers are of the following
i Pot or bowl sleeper
ii Plate sleeper
iii Box sleeper
iv CST 9 sleeper
v Duplex sleeper
i Pot or bowl sleeper Pot sleeper consist of two bowls placed under each rail and
connected together by a tie bar The total effective area of both the pots is 0 464 sq m Each
pot is provided with two holes foe inspection and packing of ballast On the top of each pot a
rail seat is provided to hold rails at an inward slope of 1 in 20 Gibs and cotters are so casted
that by interchanging them gauge is slackened by 3 mm
RAILWAY ENGINEERING Dept of Civil Engineering KLU
ii Plate sleeper Plate sleepers consists of two rectangular plates of 864 mm X 305 mm in
size with short side parallel to rail The plates are provided with projecting ribs in the bottom
to provide a grip in the ballast for lateral stability The plates are held in position by tie bar
Stiffners are provided at the top of the plate to increase the strength For mixing of rails
suitable arrangement is done as shown in Fig 5 6 It provides the effective bearing area of
0 464sq m per sleeper
iii Box Sleeper These sleepers are not in user these days Box sleepers are similar to plate
sleepers In this type of sleeper a box is provided at the top of each plate to hold the rails
iv CST 9 Sleeper CST 9 sleeper is more satisfactory than other C I Sleepers and is
extensively used in Indian Railways since last thirty years It is a combination of pot plate
and box sleeper CST 9s sleeper consists of a triangular inverted pot one on each side of rail
seat Rail seat is provided at the top to hold rails at 1 in 20 inward slope The pots are
connected across the track by means of a tie bar Fig 5 7 shows CST 9 sleeper
v Duplex Sleepers Duplex sleepers are also known as rail free duplex sleepers and have
been used at rail joints in conjunction with CST 9 sleepers These sleepers are used at rail
joints to prevent cantilever action between two supports of the CST 9 sleepers These consists
of two plates each of size 850 mm X 750 mm The plates are placed with the longer side
parallel to the rails and are connected with a tie bar Fig 5 8 shows duplex sleepers
Advantages of C I sleepers are more
i The life of C I sleepers is more
ii The maintenance cost of these sleepers is low
iii Guage can be easily maintained and adjusted with these sleepers
iv These sleepers are more durable
v Creep rails can be checked by using these sleepers
Disadvantages
i More ballast is required than any other type of sleepers
ii The number of fittings required is more
iii These sleepers are liable to break
iv C I Sleepers are liable to break
v These are not suitable for all types of ballast
4 R C C Sleepers
Reinforced cement concrete sleepers are of two types
i Through type
ii Block and tie type
RAILWAY ENGINEERING Dept of Civil Engineering KLU
i Through type R C C Sleeper This is also known as one piece or mono block
sleeper In this type of sleeper cracks develop on the tension side when stressed These cracks
are very small and almost invisible but tend to enlarge with the repetition of impact loading
causing failure
ii Block and tie type R C C Sleeper This type of sleeper consists of two R C C
blocks connected by a metal tie of inverted T section These sleepers are not subjected to any
degree of tensile stress as in through type
Advantages of R C C Sleepers
i Concrete sleepers have long life generally 40to 60 years
ii These are free from natural decay and attack by insects etc
iv These sleepers require less fittings
v Track circuiting is possible in these sleepers
vi These sleepers provide more lateral and longitudinal rigidity as compared to
other sleepers
vii The maintenance cost is low
viii Due to higher elastic modulus these can withstand the stresses due to fast
moving trains
Disadvantages
i Due to heavy weight handling and transportation of these sleepers are
ii If not handled properly the chance of breaking is more
iii The renewal of track laid with these sleepers is difficult
iv The scrap value is nil
5 Prestressed Concrete Sleepers
Prestressed concrete sleepers are now a days extensively used in Indian Railways These
sleepers have high initial cost but are very cheap in long run due to their long life In these
sleepers high tension steel wires are used These wires are stretched by hydraulic jack to give
necessary tension in the wires The concrete is then put under a very high initial compression
These sleepers are heavily damaged in caser of derailment or accidents of trains
RAILWAY ENGINEERING Dept of Civil Engineering KLU
Ballast is the granular material usually broken stone or any other suitable material which is
spread on the top of railway formation and around the sleepers
FUNCTIONS OF BALLAST
Ballast in railway track performs the following functions
i To hold the sleepers in position and preventing the lateral and longitudinal
ii To distribute the axle load uniform from sleepers to a large area of formation
iii To provide elasticity to the track It acts as as elastic mat between subgrade
and sleepers
iv To provide easy means of maintaining the correct levels of the two rails in a
v To drain rain water from the track
vi To prevent the growth of weeds inside the track
CHARACTERISTICS OF GOOD BALLAST
i It should have sufficient strength to resist crushing under heavy loads of
moving trains
ii It should be durable enough to resist abrasion and weathering action
iii It should have rough and angular surface so as to provide good lateral and
longitudinal stability to the sleepers
iv It should have good workability so that it can be easily spread of formation
v It should be cheaply available in sufficient quantity near and along the track
vi It should not make the track dusty or muddy due to its crushing to powder
under wheel loads
vii It should allow for easy and quick drainage of the track
viii It should not have any chemical action on metal sleepers and rails
TYPES OF BALLAST
In India the following materials are used as ballast
i Broken stone
RAILWAY ENGINEERING Dept of Civil Engineering KLU
iv Ashes or cinders
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 It
holds the track to correct alignment and gradient due to its high interlocking action The
stones which are non porous hard and do not flake on breaking should be used Igneous
rocks such as granite quartzite and trap make excellent ballast This type of ballast is used for
high speed tracks
ADVANTAGES
a It is hard and resist crushing under heavy loads
b It has angular and rough surface and hence gives more stability to the
c Its drainage property is excellent
DISADVANTAGES
a It is expensive
b It is not so easily available
Gravel is the second best material for ballast This is obtained either from river beds or
from gravel pits and has smooth rounded fragments Gravel obtained from pits usually
contains earth which should be removed by washing Gravel obtained from river beds is
screened and required size gravel is used Larger size gravels are broken into required size
Round edges gravels are broken to increase their interlocking action
ADVANTAGES
a Gravel is cheaper than stone ballast
b The drainage property of gravel excellent
c It holds the track to correct alignment and gradient
d It is east to use gravel ballast than stone ballast at certain places where
formation is unstable
RAILWAY ENGINEERING Dept of Civil Engineering KLU
DISADVANTAGES
a It requires screening before use due to large variation in size
b Gravel obtained from pits requires washing
c Due to round faces the packing under sleepers is loose
d Gravel easily roll down due to vibrations
Sand is reasonably a good material for the ballast Coarse sand is generally preferred to fine
sand for ballast This type of ballast is suitable for packing pot sleepers It is used only on
unimportant tracks
ADVANTAGES
a It is a cheap material
b It is available in large quantities
c It has good drainage properties
d Sand ballast produces a silent track
DISADVANTAGES
a It has no stability and gets disturbed by the vibrations caused by moving train
b It causes wear of rail seats and keys
iv ASHES OR CINDERS
These are waste products obtained from steam locomotives
ADVANTAGES
a It is a cheaper ballast material
b It has very good drainage quality
c It is available in large quantities and hence can be used in emergency
d The handling and transportation are easy
DISADVANTAGES
a It is very soft and gets crumbled to powder under heavy loads
b It has got corrosive quality and corrode steel sleepers and foot of the rails
RAILWAY ENGINEERING Dept of Civil Engineering KLU
v KANKAR It is natural material in the form of nodules from which lime is prepared
ADVANTAGES
a It is cheaper
b It has good drainage property
DISADVANTAGES
a It is soft and crumbles to powder under traffic load
b The track laid on kankar ballast are difficult to maintain
c It has corrosive quality
It is a soft aggregate and is obtained by the decomposition of laterite It has red or yellow
colour It is used in unimportant lines and sidings
ADVANTAGES
a It is easily available in most parts of India
b It has good drainage properties
c It is used as blanket for new embankment
DISADVANTAGES
a It is soft and easily crumbles to powder under heavy loads
b Maintenance of track laid on moorum ballast is very difficult
vii BLAST FURNANCE SLAG
It is a waste product obtained from the blast furnace of steel industry High grade slag
fulfils all the characteristics of good ballast
ADVANTAGES
a It is a cheap material
b It has good drainage properties
c It is a strong material
d It holds the track in correct alignment and gradient
DISADVANTAGES
a It is not available in large quantity
b Spreading of this material on the formation is difficult
c Maintenance of track laid on slag ballast is difficult
RAILWAY ENGINEERING Dept of Civil Engineering KLU
iv BRICK BALLAST At places where good ballast material is not available
over burnt bricks are broken into suitable size to be used as ballast
ADVANTAGES
a It is a cheap material
b It prevents growth of vegetation
c It has good drainage properties
DISADVANTAGES
a It is soft and easily crumbles to powder under heavy loads
b The rails laid over such ballast get corrugated
ix SELECTED EARTH Hardened clay and decomposed rock are suitable for use
as ballast When tracks are laid on new formation then sleepers are packed with earth for a
few months When the formation is consolidated and surface becomes hard good type of
ballast is laid The use of earth ballast in the beginning is to prevent the loss of good ballast
by sinking into soft formation
RAILWAY ENGINEERING Dept of Civil Engineering KLU
FIXTURES AND FASTENINGS
FIXTURES AND FASTENINGS
Fixtures and fastenings are fittings requires for joining of rails end to end and also for fixing
the rails to sleepers in a track
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
ii To fix the rails to sleepers
iii To maintain the correct alignment of the track
iv To provide proper expansion gap between rails
v To maintain the required tilt of rails
vi To set the points and crossings in proper position
TYPES OF FIXTURES AND FASTENING
Fixtures and fastenings commonly used in a permanent way are of following types
1 Fish plates
2 Bearing plates
7 Anticreepers
FISH PLATES
Fish plates are used in rail joints to maintain the continuity of the rails Two types of fish
plates are commonly used on Indian Railways for joining F F and B H rails as shown in
Fig 7 1 each fish plate is 457 mm long and provided with four holes 32 mm at a spacing of
114 mm c c These are manufactured of steel and are so designed that they fit in between the
head and foot of the rail
REQUIREMENTS OF FISH PLATES
i They should hold the adjoining ends of rails in correct horizontal and
vertical plane
ii They should allow free longitudinal movements of rails due to
temperature variation
iii They should be able to resist all types of wear
iv They should be able to bear the vertical and lateral stresses which
come at joints without any distortion
v They should allow easy renewal and replacement of rails in case of
wear and damage
RAILWAY ENGINEERING Dept of Civil Engineering KLU
BEARING PLATES
Bearing plates are cast iron or steel plates placed in between the F F rail and wooden sleepers
of a railway track F F rails if fixed directly on wooden sleepers sink in the sleeper due to the
heavy loads of trains and thus loosen the spikes To overcome this difficulty bearing plates
are used under F F rails to distribute the load over a wider area and bring the intensity of
pressure within limit
Bearing plates give the required 1 in 20 inward slope to the rail directly and no adzing is
required in the wooden sleeper These are fixed to sleepers by spikes
ADVANTAGES
Following are the advantages of bearing plates
i They distribute the loads to wider area and prevent sinking of the rail to the
ii They avoid adzing of sleepers
iii They enable the spikes to remain tight and require less maintenance
iv Bearing plates prevent the widening of gauge on curves
v Bearing plates increase the overall stability of the track
vi They prevent the destruction of the sleeper due to rubbing action of the rail
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
ii When any spike is damaged and it is required to be redriven at another
place all other spikes of the bearing plates have to be removed which will
reduce the holding power of the spikes
Spikes are used to fix rails to wooden sleepers Spikes are of following types
a Dog spikes
b Round spikes
c Screw spikes
d Elastic spikes
Dog spikes are the cheaper type of spikes which hold the rails at correct gauge
and can be easily fixed and removed These are commonly used for holding F F rails Four
dog spikes are used per sleeper two on either side of the rail The disadvantage of dog spikes
is that these become loose under the wave action caused by the moving train


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