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Prepared by
M.Shanmugaraj
Lecturer / Civil
V.S.V.N Polytechnic College
Virudhunagar
UNIT-III
RAILWAY ENGINEERING
3.1 INTRODUCTION
Amongst the different modes of
transport, Railways have their greatest
utilization in the transport of large volumes
of heavy and bulk commodities and
passengers over long distances with safety,
comfort and convenience.
History of Railways
Railways were first introduced to India in 1853
from Bombay toThane
A British engineer, Robert Maitland Brereton, was
responsible for the expansion of the railways from
1857 onwards.
The Allahabad-Jabalpur branch line of the East
Indian Railway had been opened in June 1867
In 1951 the systems were nationalised as one unit,
the Indian Railways, becoming one of the largest
networks in the world.
Indian Railways is the world's ninth largest commercial or utility employer, by number of employees, with over 1.4 million employees. As for rolling stock, IR holds over 239,281 Freight Wagons, 59,713 Passenger Coaches and 9,549 Locomotives (43 steam, 5,197 diesel and 4,309 electric locomotives).
As of 31 March 2013, 23,541 km (14,628 mi) (36%) of the total 65,000 km (40,000 mi) km route length was electrified. Since 1960, almost all electrified sections on IR use 25,000 Volt AC traction through overhead catenary delivery.
Definition
Adhesion of wheels:-
Resistance offered by the friction between the metal surface of the rail and the wheel
Adzing of sleepers:-
In order to obtain an inward slope of 1 in 20 for the rail, the sleepers are cut to form a table. The process of cutting the wooden sleeper or casting the concrete sleepers accordingly is known as Adzing of sleepers.
Ash Pits:-
Long masonry pits, constructed longitudinally inside and under
the track to collect the ash from steam locomotives
Ballast:-
Granular material used in packing under and around the sleepers
to transfer load from the sleepers.
Check rails:-
The rails, which are introduced along the inner rail of a track
on sharp curves for reducing the wear of rails, are called
‘check rails’.
Check rails are also provided along the straight rails opposite
the crossings in turnouts
Check rails:-
Bearing plates:
Mild steel, or cast iron plates used for fixing the rail with
wooden sleepers.
The rectangular plates made of either mild steel, cast iron,
wrought iron, or malleable steel which are interposed
between the foot of a flat footed rail and wooden sleeper to
distribute the load on a larger area, are called bearing plates.
Bearing plates:
Bearing plates:
Chairs:-
For keeping the bull headed rail in proper position, special
devices are provided in between the sleepers and the rails
which is known as the Chairs.
Chairs :
Coning of wheel:-
"Coning of wheels" is what allows a train to take a turn
without slipping off its tracks.
Coning of wheel:-
Creep of rails:-
The longitudinal movement of rails, in a track is known as
creep of rails
Drop Pits:- Pits constructed in the loco shed for taking down wheels of
the locomotive during repair.
Examination Pits:-
Pits constructed for examination of the engines underneath
Detectors:- A defect detector is a device used on railroads to detect
axle and signal problems in passing trains. The detectors are
normally integrated into the tracks and often include sensors
to detect several different kinds of problems that could occur.
Hogged Rails:-
A Hogged Rail is the surface defect of the rail in which the
rail ends are bent downward at the joints.
Kinks:-
Lateral shift in rails due to loose joints and defective gauge is
called as Kinks
Flag Stations:-
A railroad station where trains stop only when a flag or other
signal is displayed or when passengers are to be discharged.
Fouling Mark:-
It is the point beyond the converging point of two or more
tracks before which train on one of those tracks have to be
stopped so that train movement is not obstructed in other
tracks.
Gang Hut:-
Residential quarters provided near the centre of the gauge
beat are called gang hut
Guard Rails:-
Extra rails provided over bridges to prevent damage and
derailment on the bridge
Heel:-
Tapered rail fixed to the main rails are called Heel.
Level crossing:-
Place when the road and railway line cross each other at the
same level.
Rolling stock
Rolling stock comprises all
the vehicles that move on a railway
It usually includes both powered and
unpowered vehicles, for example
locomotives, railroad cars, coaches,
and wagons
Stock rail:-
This is the main rail at the switch where the tongue rail
fits against it.
Stock rail:-
Tongue rail:-
Tapered rail used in switch
Tube railways:-
Underground railways at about 27m or more in depth below
the ground
Railroad station:
Set of installations of a railway, where passengers embark and
disembark and goods are loaded and unloaded.
Water tower:
water container.
Tunnel: underground passage.
Viaduct: railway bridge.
Bridge: Construction that allows passage between two points
separated by a depression or an obstacle.
Overpass:
Elevation of a railway over a highway so they do not
intersect.
Engine shed: Place where locomotives are
stored.
Rails
A steel bar or continuous line of bars laid on the ground as
one of a pair forming a railway track.
Sleeper
It is one of the cross braces that support the rails on a railway
track
Ballast Track ballast forms the track bed upon which railway
sleepers are laid
Gauge
Rail gauge is the distance between the inner sides of the two
parallel rails that make up a single railway line
Turn out
A complete set of points and crossings along with a lead rail
is known as turnout
Turn out
Right Hand Turn out
If a train from main track is diverted to the right of the main
route in the facing direction, then this diversion is known as
Right-hand turnouts
Left Hand Turn out
If a train from main track is diverted to the left of the main
route in the facing direction, then this diversion is known as
Left-hand turnouts.
Points and Crossing Special arrangement on railway track for enabling trains to
divert from one track to another
Yards
System of tracks for various purposes such as receiving,
storing and despatch of goods, wagons and passenger
coaches, etc.
Signals
Device by which movement of train is controlled
Rail Gauges
Rail gauge is the distance between the inner sides of the two
parallel rails that make up a single railway line
Rail gauge is the distance between two rails of a railroad.
Sixty percent of the world's railways use a 4 feet 8½ inch
(1435 mm) gauge, which is known as standard gauge or
international gauge.
Rail gauges larger than standard gauge are called broad
gauge, and rail gauges smaller than standard are called
narrow gauge.
A dual gauge railway has three or four rails positioned so
that trains of two different gauges can use it.
A place where different gauges meet is called a break of
gauge.
Rail Gauges
Types of Rail Gauges
The different gauges prevalent in India are of the
following these types :-
Broad gauge (1676),
Metre gauge (1000),
Narrow gauge (762 mm & 610 mm).
Types of Rail Gauges
1.Broad Gauge
When the clear horizontal distance between the
inner faces of two parallel rails forming a track is
1676mm the gauge is called Broad Gauge (B.G)
This gauge is also known as standard gauge of
India and is the broadest gauge of the world.
The Other countries using the Broad Gauge are
Pakistan, Bangladesh, SriLanka, Brazil,
Argentine,etc.50% India’s railway tracks have
been laid to this gauge.
Suitability :-
Broad gauge is suitable under the following
Conditions :-
(i) When sufficient funds are available for the
railway project.
(ii) When the prospects of revenue are very
bright.
This gauge is, therefore, used for tracks in plain
areas which are densely populated i.e. for routes
of maximum traffic, intensities and at places
which are centers of industry and commerce
2.Metre Gauge
When the clear horizontal distance between the
inner faces of two parallel rails forming a track is
1000mm, the gauge is known as Metre Gauge
(M.G)
The other countries using Metre gauge are
France, Switzerland, Argentine, etc. 40% of
India’s railway tracks have been laid to this gauge.
Suitability :-
Metre Gauge is suitable under the following
conditions:-
(i) When the funds available for the railway
project are inadequate.
(ii) When the prospects of revenue are not very
bright.
This gauge is, therefore, used for tracks in under-
developed areas and in interior areas
3.Narrow Gauge
When the clear horizontal distance between the
inner faces of two parallel rails forming a track is
either 762mm or 610mm, the gauge is known as
Narrow gauge (N.G)
The other countries using narrow gauge are
Britain, South Africa, etc. 10% of India’s railway
tracks have been laid to this gauge.
Suitability :-
Narrow gauge is suitable under the following conditions :-
( i) When the construction of a track with wider gauge is
prohibited due to the provision of sharp curves, steep
gradients, narrow bridges and tunnels etc.
(ii) When the prospects of revenue are not very bright.
This gauge is, therefore, used in hilly and very thinly
populated areas. The feeder gauge is commonly used for
feeding raw materials to big government manufacturing
concerns as well as to private factories such as steel plants,
oil refineries, sugar factories, etc.
Uniformity in gauges
One country should have only one gauge
throughout its various parts.
But the policy of India and its Topographical,
Geological and Financial conditions have led to
adopt various gauges in its different parts.
Advantages of Breaking the Gauge
i). The most effective advantage of breaking the gauge is to
render the railway an economical and profitable concern.
ii). It facilitates the provision of a steeper gradient, sharp
curves and narrow tunnels by adopting a less wide gauge in
hilly and rocky areas.
Disadvantages of Breaking the
Gauge :-
i). It causes much inconvenience to the passengers while
changing the train at station, with change of gauge.
ii). It causes delay in movement of people and goods.
iii). It results in wastage of time.
iv). It involves extra labour for unloading and reloading the
goods. The goods are also likely to be damaged or dislocated at
the junction station, having change of gauge.
v). It requires the provision of extra and costly transshipment
yards, godowns, sheds, etc. at every junction station having
change of gauge.
vi). It causes extreme difficulty in quick movement of military
and ammunition during war days.
Loading gauge
A loading gauge defines the maximum height and width
for railway vehicles and their loads to ensure safe passage
through bridges, tunnels and other structures.
The loading gauge determines the sizes of passenger trains
and the size of shipping containers that can be conveyed on a
section of railway line and varies across the world and often
within a single railway system.
Loading gauge
A loading gauge is the envelope or contoured shape within
which all railroad cars, locomotives, coaches, buses, trucks
and other vehicles, must fit.
It varies between different countries and may also vary on
different lines within a country. For example, metro trains
might have smaller loading gauge than conventional trains to
allow smaller tunnels.
In that case metro trains may run on conventional tracks, but
not vice versa.
Loading gauge
Loading gauge
Loading gauge
In more recent times, the term loading gauge has fallen
out of use among railway professionals, since it is a purely
static concept and ignores other factors affecting clearance.
Indian Railways 1,676 mm (5 ft 6 in) gauge track have very
large loading gauge. 3,660 mm (12 ft 0 in) wide and
5,300 mm (17 ft 5 in) high for passenger traffic.
In India 3,250 mm (10 ft 8 in) wide and 7,000 mm
(23 ft 0 in) high on the freight only lines, and 3,250 mm
(10 ft 8 in) wide and 6,150 mm (20 ft 2 in) high on the
passenger lines.
The smallest loading gauge for a railway of
the 1,676 mm (5 ft 6 in) gauge track is Delhi Metro.
Which is 3,250 mm (10 ft 8 in) wide and 4,140 mm
(13 ft 7 in) high.
Construction gauge.
By adding suitable clearance at the top side of the
loading gauge construction gauge is obtained.
It decides the dimensions such as height and
width of structures in bridges and tunnels along
the track so that all wagons may pass through
them without damage to the structures
RAILS
General
Rail is similar to steel girders. These are placed end to end to
provide continuous and level surface for the trains to move
Functions of Rail:
To provide continuous and level surface for
movement of train.
To provide a smooth pathway so that friction
between rail and wheel become less.
Serve as a lateral guide for the running of wheels.
Transferring the load into the sleeper.
To bear the stresses developed in the track due to
temperature changes and loading patterns.
To resist breaking forces caused due to stoppage
of trains.
Requirements of an ideal railThe main requirements of an ideal rail section are as under:
(1) The section of the rail should be such that the load of
eh wheels is transferred to the sleepers without
exceeding the permissible stresses.
(2) The section of the rail should be able to withstand the
lateral forces caused due to fast moving trains.
(3) The underside of the head and top of the foot of the
rail section should be of such a slope that the fishplates fit
snugly.
(4) The center of gravity of the rail section should
preferably coincide the center of the height of the rail so
that maximum tensile and compressive stresses are nearly
equal.
(5) The web of the rail section should be such that it can safely
bear the vertical load without buckling.
(6) The head of the rail should be sufficiently thick for
adequate margin of vertical wear.
(7) 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.
(8) 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.
(9) The surfaces for rail table and gauge face should be
sufficiently hard to resist the wear.
(10) The contact area between the rail and wheel flange should
be as large as possible to reduce the contact stresses.
(12) The composition of the steel should conform to the
specifications adopted for its manufacture by Open Hearth of
Duplex Process.
(13) The overall height of the rail should be adequate to provide
sufficient stiffness and strength as a simply supported beam.
(14) The stiffness of a rail section depends upon the moment of
inertia. The economical design should provide maximum
moment of inertia per unit weigh of rail with due regard to
other factors.
(15) The section modulii of the rail section and that of a pair of
fish plates should be adequate so as to keep the rail and fish
plates within permissible limits.
(16) The foot of the rail should be wide enough so that the rail
is stable against overturning.
Types of rail sections
1. Double headed rails
2. Bull headed rails
3. Flat footed rails
Types of rail sections
Types of rail sections
Double headed rails:
These were the rails which were used in the beginning, which
were double headed and consisting of a dumb-bell section.
The idea behind using these rails was that when the head was
worn out in course of time, the rail can be inverted and
reused.
But as time passed indentations were formed in the lower
table due to which smooth running over the surface at the top
was impossible.
Bull headed rails:
In this type of rail the head was made a little thicker and
stronger than the lower part by adding more metal to it, so
that it can withstand the stresses.
Flat footed rails: These rails are also called as vignole's rails.
Initially the flat footed rails were fixed to the sleepers
directly and no chairs and keys were required.
Later on due to heavy train loads problems arose which
lead to steel bearing plates between the sleeper and the
rail. at rail joints and other important places these are the
rails which are most commonly used in india.
Length of rails
The most common length for BG rails is 13m (42'8'')
although double-length rails (26m, 85'4'') are seen in
some places.
MG rails are usually 12m (39'4'') in length.
NG rails vary, but the commonest length is 9m (29'6'').
Much earlier (before the metric system was adopted!),
rails were generally produced in sizes of 11, 12, or 14
yards (33', 36', 42'), less commonly 13 yards (39') or 10
yards (30' - NG).
Factors governing length of rails:-
Manufacturing cost
Transportation facility
Lifting and handling operation
Welding of railsPurpose of welding:
To increase the length of the rails
To repair the worn out or damaged rails
To build up worn out points and rails on the sharp curves
Welded rail sections are of two
types:
Short Welded Rail or SWR which consists of just
two or three rails welded together, and Long
Welded Rail or LWR which covers anything
longer.
The welding of rails is carried out in a depot by
the "Flash butt welding process and at site by the
"ThermitWelding" process.
Advantages of welding rails: (1) Welding of rails increases the life of the rails due to decrease in
wear of the ends.
(2) Welded rails provide more comfort to the passengers due to
smooth running of wheels over welded joints.
(3) Welding of rails reduces the creep because frictional resistances
increase with the increase in rail length.
(4) As discontinuity of rails is reduced, the defects such as
hammering rail joints, displacement of joint, disturbance in
alignment and running surface, are also eliminated.
(5) A welded rail panel provides better track circuiting on the
electrified tracks.
(6) Welded rails provide better performance and reduce the effects
of impact on large span bridges.
(7) Long welded rail length dampens the intensity of high frequency
vibrations due to moving loads.
(8) Welding increases the life and decreases the wear of rails.
(9) By welding of rails, the cost of track construction decreases due to
elimination of a large number of rail joints.
(10) Fast and heavy traffic may be permitted on track with welded rails.
(11) The use of long welded rails, affords better longitudinal, lateral
and vertical stability to the track.
(12) In a welded rail panel, the number of joints is less. This saves the
fuel consumption as it eliminates the loss of strain and impact energy at
the rail joints.
(13) In welded rail panels, the risk of sabotage and accidents, are
considerably reduced.
(14) Welding of rails reduces the maintenance cost by about 20% to
40%.
Wear of rails Wear on head of rail
Wear on ends of rail
Wear of rail on curve
Wear on head of rail Wear on head of rail is due to abrasion on moving rails.
Due to grinding action of sand or dust between the rails and
wheels of the train.
When train starts or applies brakes, the wheel just slides on
the rails causing wear on the head.
Load coming on to a track may exceed the carrying capacity
of the section. Thus causing the wear in the head of rail.
Wear on ends of rail It is much greater than the wear on the head of the rail.
This type of the wear is resulted due to the blows which
the rail receive when the wheel jumps the space between
the rail ends.
The ends are battered by such blows.
The contact surface between the sleepers and the rail is
worn as the as the effect of these blows increased.
The ballast under the sleepers will loosen due to increase
in the intensity of vibrations, also he sleeper will
depressed due the displacement of ballast, also the fish
plates will get loose under the constant impact of
increasing vibrations
Wear on ends of rail
Wear of rail on curve On the curve the wear of the rail takes place in both inner
and outer rails.
On the curve, the outer wheel has to move through greater
distance than the inner wheel. And the inner wheel has to
slide over the inner rail.
As a result of this sliding wear of the inner rail occur because
the metal in the rail head is burnt.
Wear of rail on curve
Coning of wheels
The flanges of wheel is never made flat, but they
are in the shape of cone with a slope of 1 in 20.
(Sloping of the wheel from the vertical axis)
The coning of wheels is mainly done to maintain
the vehicle in the central position with respect to
the track.
It is done to maintain the vehicle in the central
position with respect to the track
Coning of wheels
Advantages of coning the wheels
(i) Coning the wheels reduces the depreciation of
the wheel rims and rails. Depreciation is caused
because of the friction action of rims with inner
faces of the rail top.
(ii) Coning also gives an option of lateral drift of
the hinge with is wheels.
(iii) Coning also prevents, to some extent, the
slipping of the wheels.
Hogged rails
A hogged rail is one with its end or ends bent in vertical
direction. Caused due to battering action of wheels
Causes of Hogging
Due to loose packing under the joints and loose fish
plates.
Preventing steps
Hogged rails are removed and replaced by new rails.
Deflected ends can be brought in to their original shape
and size by welding
The deflected ends of the rails are cut off and fresh holes
drilled for fixing the fish plates.
The bent or deflected ends of rails can be straightened
Bending of rails
On curves the rail is bent true to the curvature
of the curve. In flat curves less than 30 the rails
need no bending as they are retained in curve
position by the sleepers.
With curves more than 30 it is desirable to
bend the rails before fixing them with sleepers.
Bending of rails
Creep of rails
It is defined as the longitudinal movement of rails with
respect to sleepers in a track.
Causes of creep:
Wave motion of trains.
Expansion and contraction of rails due to variation in
temperature.
Due to starting, accelerating, slowing down (decelerating)
and stopping of trains.
Rail deflection under the moving loads from the wheels
Heavy traffic in one direction
Greater on curves
Old rails have more creep
More with steep gradient
Poor maintenance of track
Effects of Creep:
Expansion gap is reduced, buckling of track take
place.
Sleepers are moved out of a square.
Crossing points get disturbed.
Rail joints are opened, stresses are set up in fish
plates and bolts.
Movement of switches is made difficult
Smashing of fish plate, bolts, bending of bars,
kinks at joints
Prevention of creep:
Pulling back the rails
Provision of Anchors
Use of steel sleepers
Efficient and proper maintenance
SLEEPERS AND BALLAST
Definition:
Sleepers are used as a base for laying railway tracks. Sleepers
were traditionally made from wood but are now usually
made from concrete.
Ties are laid on top of sand, gravel or heavy crushed stone -
called ballast.
SLEEPERS AND BALLAST
SLEEPERS AND BALLAST
Functions of Sleepers In a railway track, sleepers perform the following functions:
(1) To hold the rails t proper gauge in all situations. i.e. exact gauge
along straights and flat curves, slightly loose on sharp curves and
slightly tight in diamond crossings.
(2) To support the rails firmly and evenly throughout.
(3) To distribute the load transmitted through rails over large area of
ballast underneath or to the bridge girders as the case may be.
(4) To hold the rails to proper level in turnouts and crossovers, and
at 1 in 20 in ward slope along straight tracks.
(5) To provide and elastic medium between the rails and ballast and
also to absorb the vibrations caused due to moving axle loads.
(6) To maintain proper alignment of the track. On curves proper
cant is provided by raising the outer rail and tamping he required
quantity of ballast bellow th rails.
(7) To provide the general stability of the permanent
way throughout.
(8) To provide the insulation of track for the
electrified for signaling.
(9) To provide easy replacement of the rail fastenings
without any serious traffic disturbances
(10) Holding rails to correct gauge and alignment.
(11) Firm and even support to rails.
(12) Transferring the load evenly from rails to wider
area of ballast.
(13) Elastic medium between rails and ballast.
(14) Providing longitudinal and lateral stability
Requirements of a good Sleeper A good sleeper should meet the following requirements:
(1) The initial cost and the maintenance cost of the sleepers
should be low.
(2) The fittings required for fixing the rails on to the sleepers,
should be simple which can be easily adjusted during the
maintenance.
(3) The crushing strength of the sleepers should be more with
moderate weight.
(4) They should be able to maintain a perfect alignment, gauge
and levels of the rails and should afford efficient adjustment and
maintenance.
(5) They should provide sufficient bearing area to hold the rail
seats and for the ballast to be supported on, to resist the crushing
due to movement of heavy axle loads.
(6) The sleeper spacing should be such as t remove and
replace the ballast during regular maintenance operation.
(7) They should be capable to resist the shocks and
vibrations caused due to fast moving vehicles at high
speeds.
(8) They should provide insulation facilities for track
circuiting in the electrified sections.
(9) The sleepers should be strong enough to withstand the
pressure during packing process.
(10) The sleepers should be of such a design that they
remain in their positions and do not get disturbed due t
moving trains.
(11) The material used for the sleeper be such that it does
not attract the sabotage and the theft qualities.
Types of Sleepers
Sleepers based on the materials
Timber sleepers
Steel sleepers
Cast iron sleepers
R.C.C sleepers
Pre-stressed concrete sleepers.
Sleepers depending on the location
Longitudinal sleepers
Transverse sleepers
Longitudinal sleepers
These are earlier form of sleepers which are not
in use nowadays.
It consists of slabs or pieces of timber placed
parallel to the rails.
To maintain the correct gauge cross pieces were
provided.
These sleepers were costly
Noise created by the track is considerable
Longitudinal sleepers
Transverse sleepers
Also knows as cross sleepers.
Placed at right angles under the rails.
Eliminated the inconvenience of
longitudinal sleepers
Transverse sleepers
Timber sleepers (Wooden sleepers)
Ideal type and universally used they are two categories of
hard wood sleepers such as Sal, Teak, Kongu etc., and soft
vwood sleepers such as deodar, chir, treated timbers are use
in this categories.
Timber sleepers (Wooden sleepers)
Advantages of Wooden Sleepers:
(1) They have proved very useful for heavy loads and high-
speed trains.
(2) They are cheap and easy to manufacture.
(3) They can be handled easily without any damage.
(4) They maintain the correct alignment.
(5) They are most suitable for track circuiting.
(6) They can be used with or without ballast.
(7) They can be used for gauntlet tracks.
(8) They are suitable in the areas having yielding
formations.
Disadvantages of Wooden Sleepers: They are easily subjected to wear and decay due to various
factors, i.e. vermin, white ants, rail-cutting, warping, etc. Hence,
these have a short life.
(1) They do not maintain the gauge accurately.
(2) They easily develop cracks with beater packing.
(3) They require the highest maintenance cost as compared to
other types of sleepers.
(4) They get easily disturbed from their positions under heavy
loads.
(5) They need special treatment for fire protection.
(6) Their scrap value is low.
(7) They are not suitable for modern LWR track because of their
lighter weight.
Description of Wooden Sleepers
Size of wooden sleepers in mm : B.G. : For
ordinary track 2750x250x130 (9ᾼx10῀x5῀)
Life of Sleeper: Durable 19 years (B.G.)/ 31
years (M.G.)
Steel sleepers They are in the form of steel trough on which rails are fixed
by keys or nuts or bolts
Advantages of steel Sleepers
The steel sleepers possess the following advantages:
(1) They are manufactured by a simple operation.
(2) They can be easily handled as theses are light in
weight as compared to other types of sleepers. Hence,
damages during handling and transporting are less.
(3) Less number of fastenings are required and that too
simple in nature.
(4) The maintenance and adjustment of gauge are easy as
compared to the other of sleepers.
(5) These sleepers are rolled sections in one piece.
(6) Their life is longer than that of other types of
sleepers.
(7) They provide better lateral rigidity to the track.
(8) They are not attacked by vermin’s.
(9) They are not susceptible to fire hazards.
(10) Their scrap value is good.
Disadvantages of Steel of Sleepers
The steel sleepers possess the following disadvantages:
(1) They get easily rusted and corroded.
(2) They develop cracks at rail seats or near lugs.
(3) Their lugs get broken easily.
(4) The steel sleepers do not provide effective track circuiting
(5) The steel sleepers can only be for the type of rails for
which theses are manufactured.
(6) These develop the tendency to become center bound
because of slope at both ends.
(7) The overall cost of steel sleepers is more than that of
timber sleepers.
Cast iron sleepers
Sleepers made of cast iron are called cast iron sleepers
Type of Cast Iron Sleepers :
A) C. I. Pot Sleepers
B) C S T- 9 Sleepers
Cast Iron Pot type sleepers
Consists of two hollow pots of circular or elliptical shape
placed inverted on the ballast section.
Two pots are connected by the tie bars of section 5cm X
1.25cm,
Each pot has two hoes for ballast packing and inspection, the
rail is placed on the top of the pot in a rail seat
Cast Iron Pot type sleepers
Cast Iron Plate type sleepers
Consist of rectangular plates of size about 86cm X 30.5cm,
with projecting ribs under the plates for their lateral stability.
The tie bars can be fixed to the plate keys, gibs, cotter keys
and distance piece etc.
It also provide an effective bearing area on BG
Cast Iron Plate type sleepers
Advantages of Cast Iron Sleepers
• Long life upto 50-60 years
• High scrape value as they can be remolded
• Can be manufactured locally
• Provided sufficient bearing area
• Much stronger at the rail seat
• Prevent and check creep of rail
• They are not attacked by vermin
Disadvantages Cast Iron Sleepers
• They are prone to corrosion and cannot be used in salty
formations and coastal areas
• Not suitable for track circuited portions of railways
• Can badly damage under derailment
• Difficult to maintain the gauge as the two pots are
independent
• Require a large number of fastening materials
• Difficult to handle and may be easily damaged
• Lack of good shock absorber
• They are expensive
Concrete sleepers
R.C.C and pre-stressed concrete sleepers are now replacing
all other types of sleepers except to some special
circumstances such as crossing bridges etc here timber
sleepers are used.
They were first of all used in France round about in 1914 but
are common since 1950.
They may be a twin block sleepers joined by an angle iron.
It may be a single block pre-stressed type.
Concrete sleepers are much heavier than wooden ones, so
they resist movement better.
Concrete sleepers
Advantages Concrete Sleepers • Durable with life range from 40-50 years
• They can be produced on large quantities locally by installing a plant
• Heavier than all other types thus giving better lateral stability to the
track
• Good insulators and thus suitable for use in track circuited lines
• Efficient in controlling creep
• They are not attacked by corrosion
• Free from attacks of vermin and decay, suitable for all types of soils
• Most suitable for welded tracks
• Prevent buckling more efficiently
• Initial cost is high but proves to be economical in long run
• Effectively and strongly hold the track to gauge
• Inflammable and fire resistant
Disadvantages Concrete Sleepers
• Difficult to be handled
• Difficult to be manufactured in different sizes thus
cannot be used in bridges and crossing
• Can be damaged easily while loading and unloading
Pre-stressed concrete sleepers.
The concrete is put under a very high initial compression.
All the disadvantages of RC sleepers have been eliminated by
pre stressing sleepers
Two types of pre stressed sleepers (i) Pre-tensioned sleeper
(ii) Post tensioned sleeper
Pre-stressed concrete sleepers.
Sleeper Density Sleeper density= Number of sleepers per unit rail length (per
unit track length for welded rail)
Number of sleepers per rail varies from N+3 to N+6 for main
tracks, N-Length of the rail
Minimum Density
MKS: Minimum sleeper density= M+7 (BG)
FPS: Minimum sleeper density= N+3 (MG)
Factors affecting spacing/density
Axle load and speed
Type and section of rails
Type and strength of sleepers
Type of ballast and ballast cushion
Nature of formation
Ballast It is a layer of broken stones, gravel or any other such gritty
material laid and packed below and around sleepers.
The material used as an elastic cushion between the sleeper
and the top of the formation, is called ‘Ballast’
Requirements of Good Ballast Ideal ballast should possess the following characteristics:
(1) It should resist crushing under dynamic loads.
(2) The designed depth of the ballast should be able to distribute
the weight of passing trains on the formation underneath
uniformly.
(3) It should not make the track dusty due to powder formation
under dynamic wheel loads.
(4) It should be reasonably elastic.
(5) It should have resistance to abrasion and weathering
(6) It should be non-porous to provide durability to the ballast.
(7) It should hold the sleepers laterally and longitudinally under
all conditions traffic, especially on the curves.
(8) It should be able to facilitate easy drainage to rain water
Functions of Ballast The main functions of ballast of a railway track are as under:
(1) It provides a hard and level bed for the sleepers.
(2) It holds the sleepers in proper position during the passage
of moving trains.
(3) It provides to some extent an elastic bed for the track.
(4) It transmits and distributes the moving load of the trains
from the sleepers to the formation uniformly.
(5) It protects the formation surface from direct exposure to
sun, rain and frost.
(6) It provides a proper drainage to the track, keeping the
sleepers in dry condition.
Functions of Ballast
(7) It obstructs the growth of vegetations at the track
formation.
(8) It provides proper super elevation to the outer rail on
curves.
(9) It provides an easy means for correcting the unevenness
of the track.
(10) It provides the lateral and longitudinal stability to the
track
(11) It protects the sleepers from capillary moisture of
formation.
(12) It provides a media for absorption of all impacts caused
by rolling stock.
Types of Ballast
Keeping in vies the availability, workability, durability
and strength of the ballast different materials have been
used as ballast. The most important types of ballast
materials used in.
(1) Broken stones (2) Gravels (3) Sand (4)Moorum (5)
Cinder (or ash) (6) Brick bats
(7) Kankar (8) Ballast earth.
(1) Broken stone: Best material for railway track.
Due to high interlocking action it holds the track to the
correct alignment and gradient
Granite, Quartzite, hard stones, lime stones are some of the
varieties of stones
(2) Gravel: Obtained from river beds or pits
Cheaper than broken stone
Has excellent drainage property
Requires screening before use
(3) Ashes and Cinder: Residue obtained from coal used in locomotives is cinder
Has good drainage property
Corrosive property
Should not be used where steel sleepers are used
(4) Sand: Best materials for ballast
Good drainage property
Gives silent track
Good for packing of cast iron pot sleepers
(5) Moorum: Decomposed laterite rocks
Red in colour
Under heavy loads crumbles to powder
Used in sidings and embankments
(6) Kankar: Found in the form of nodules of varying size
Useful for metre gauge and narrow gauge tracks with light
traffic
(7) Brick ballast: Over burnt bricks are broken in to small pieces, used as
ballast
Fairly good enough drainage property
Becomes powder under heavy traffic and tracks become
dusty.
(8) Selected earth:
Good quality earth can be used for newly laid tracks and
sidings
RAIL FASTENINGS AND PLATE
LAYING
Rail joints
Rail joints are necessary to hold the adjoining ends of the
rails in the correct position, both in the horizontal and
vertical planes
Weakest part of the track
In order to Provide expansion and contraction due to
variation in temperature, certain gap is provided at each
joint.
This gap causes a break in continuity of rails in horizontal
as well as in vertical plane, forming the weakest point of
the track.
RAIL FASTENINGS
Types of Rail Joints
According to Position of joints
(i)Square joints (ii) Staggered joints
According to position of sleepers
(i) Suspended joints(ii) Supported joints (iii)
Bridge joints (iv) Insulated joint (v) Compromise
joint
According to Position of joints
Square Joints:
Joint in one rail is exactly opposite to the joint in the other
parallel rail is called as Square Joint
Common in straight tracks
Staggered Joints:
Joint in one rail is exactly opposite to the centre of the other
parallel rail is called as Square Joint
In India this type of joint is used in curves
It gives smoother running to the track.
According to Position of joints
According to position of sleepers(i) Suspended joints:
The rail joint when placed at the centre of two consecutive
sleepers is known as suspended joints
The load is evenly distributed on two sleepers.
When joint is depressed both rails are pressed down evenly
(ii) Supported joints:
When the sleeper is placed exactly below the rail joint, it is
known as supported joint.
Do not give sufficient support with heavy axle loads
(iii) Bridge joints: Similar to suspended joint, but a metal serving as a bridge to
connect the ends of two rails
The bridge is placed at the bottom of rails and it rests on
two sleepers
Rail fastenings: A rail fastening system is a means of fixing rails to railroad
ties.
The terms rail anchors, tie plates, chairs and track fasteners
are used to refer to parts or all of a rail fastening system.
Various types of fastening have been used over the years.
Rail fastenings:
Fish Plates:
Fish Plates:
A fishplate, splice bar or joint bar is a metal bar that is
bolted to the ends of two rails to join them together in
a track
The top and bottom edges are tapered inwards so the
device wedges itself between the top and bottom of the
rail when it is bolted into place.
In rail transport modelling, a fishplate is often a small
copper or nickel silver plate that slips onto both rails to
provide the functions of maintaining alignment and
electrical continuity
Fish bolts:
Fish Bolts:
Made up of medium or high carbon steel.
Fish bolts have to undergo shear due to heavy
transverse stresses.
Length depends on the type of fishplate used
For 44.70Kg rail, a bolt of 2.5cm dia and 12.7cm
length is used
These bolts get loose by the traffic variations and
require tightening from time to time
Spikes:
A rail spike (also known as a cut
spike or crampon) is a large nail with an offset
head that is used to secure rails and base plates
to railroad ties in the track.
Spikes:
Chairs and Keys: Chairs are required to hold bull headed rails and double headed rails in
position
Made of cast iron and help in distributing the load from the rails to thee sleepers
It consists of two jaws and a rail seat.
The web of the rail is held tightly against
the inner jaws of the chair and a key is
driven between the rail and the outer jaw
of the chair
The chair are fixed with the sleepers by
means of spikes
The shapes of chairs depend upon the type
of rails used.
Chairs and Keys:
Keys:
They are wedge-shaped wooden or metal pieces.
They keep the rail in proper position
Wooden keys are cheaper but liable to be
attacked by vermin’s, the initial cost of metal key
is more but their life is ten to 15 times more than
wooden keys.
Bearing plates:
Rectangular plates made up of mild steel or cast iron
Used below flat footed rails to distribute the load on a larger area
Prevents damage of the sleepers due to rubbing action
Holds the spike firmly to the sleepers
Bearing plates:
Bearing plates:
Blocks:
To hold the check rail at the required
distance, small blocks of steel are inserted in
between two rails
These blocks may touch either the webs or
the fishing faces or both
Blocks:
Elastic fastenings:
A rail fastening system is a means of
fixing rails to railroad ties
The conventional rigid fastenings are
not able to meet the higher stresses.
Therefore elastic fastenings are used
This may protest against the shocks,
vibrations
Elastic fastenings:
Elastic fastenings:
Elastic fastenings:
Requirements of Elastic fastenings:
It should have sufficient elasticity
It should provide longitudinal and lateral rigidity to the track
It should be able to use all types of sleepers
It should be durable
It should be easy to insert and remove
Anchors and anti-creepers:
Creep can be checked by using Anchor and Anti-creepers.
Anchors are fastenings which are fixed to the sleepers at foot of rails
Anchors are fixed at come required intervals in the rails
They depend up on the traffic, curves points, crossings
Anchors and anti-creepers:
Anchors and anti-creepers:
Anchors and anti-creepers:
Plate laying:
The operation of laying out and connecting
sleepers and connecting rail and sleepers is
known as Plate laying
The point of commencement of the new track
to be laid is the existing rail head
In new track sleepers are laid directly over the
formation, after compaction the track is then
lifted and ballast is packed around the sleeper
Methods of plate laying:
Tram line method or side method
Telescopic method
American method
Tram line method or side method:
This method is used for plate laying in flat country
Used when new track is laid nest to the existing track
For plate laying of new track, either of the following two methods may be adopted
(i)A service road is constructed parallel to the proposed track and the materials are transported to the site of the work
Tram line method or side method:
(ii)A temporary rail line parallel to the proposed
track and the materials are transported in
wagons. This temporary line is known as tram
line
In this method all the materials are taken from
the central depot in material trains on the
existing track and are spread on the formation of
new track
After completing spreading, the work of
assembling is started from one end manually
Telescopic method:
This method is used very widely in India
A large central depot is constructed near the
junction of the existing railway or highway and
the proposed railway line
The manual force is divided in to (i)Material gang
(ii)Linking-in-gangs (iii)Packing-in-gangs
(i) Material gangs:
These gangs unload the materials from the
trains
They carry the materials to the rail head and
supply them to the linking-in-gangs.
These gangs distribute sleepers, rails,
fishplates, bolts etc. to the required places
(ii) Linking-in-gangs:
These gangs mark the centre line of the proposed track and place the sleepers at required place
Rails are placed on the sleepers
Successive rails are joined together by fishplates, bolts with expansion joints
After joining the rails are fixed to the sleepers
(iii) Packing-in-gangs:
These gangs correct the rails to the
required level and gradients by packing
earth or ballast below and around the
sleepers
American method
This method involves all mechanical work
This method consists of fixing rails to the sleepers
and lifting the whole unit by heavy cranes.
First one is linked with the rail head, then the
train moves ahead by one rail length and the same
procedure is repeated.
This method is un-economical one and is not used
in India
Plasser Quick Relaying System (PQRS
method)
This is a mechanical method of laying railway track in Indian
Railways
This method is used for relaying existing track under traffic
condition without interrupting the flow of traffic
Following equipments are used for PQRS method of plate
laying
(i)Sleeper layer (ii)5 tonne portal crane (iii)Track jacks
(iv)Hand gantries (v)Engine (vi)B.F.R (open wagon for
carrying long rails) (vii)B.F.R for carrying sleeper
(viii)B.F.R for old materials
Plasser Quick Relaying System (PQRS
method)
Auxiliary track
An auxiliary track is laid with a gauge length of 3.4m.
This is to carry the required equipments and materials for laying new work.
The auxiliary track is laid over wooden blocks on cast iron posts at two metres interval.
The level of auxiliary track is laid with the same level of track.
The portal crane moves on the auxiliary track and it is used to lift and carry the rail panels.
Sleepers layers is a machine which is used for laying sleepers with required spacing and alignment
The jacks are used to support the track laying at uniform level. Hand gantries are used for moving the rails in longitudinal direction at lifted position.
Method of relaying:
Work of relaying the track is normally divided
into the following stages:
(i)Preliminary work:
To prepare schedule of materials per 100m length
or per km of the track.
The entire quantity is collected at the central
store, from which day to day requirements is
drawn
(ii)Laying of the track:
Removal of the fittings.
Removal of rails and sleepers
Placing of new sleepers
Laying of rails
Laying of second rail
Finishing
(iii)Construction of the track:
Tightening of the fittings
Distribution of ballast
Further packing of ballast
Return of released material to store
MAINTENANCE OF TRACK
Necessity of Maintenance of track:
Increases the life of track
Provides comfortable ride to the passenger
Provides safety to goods
Increase the life of rolling stock
Operating cost is reduced
Safety to passengers
Maintenance of track:
The railway track requires proper watch and
ward for security reasons
Maintenance of railway track consists of
(i) Daily maintenance (ii) Periodic Maintenance
For daily maintenance the track is divided in
to sections of 5 to 8 kms lengths.
Each section is look after by a gang
The daily maintenance consists of
General inspection of the track
Checking up of all fastenings and fittings
Tightening of bolts wherever required
Reporting by unusual occurrence
The periodic maintenance consists of detailed inspection of
the track to detect defects in the track which may not be detected
during daily maintenance.
The various aspects of periodic maintenance are as below
Maintenance of track alignment
Maintenance of track drainage
Maintenance of track components
Maintenance of level crossing
Maintenance of track materials:
The top surface of the rails should be kept at the same level
Ballast under sleepers should be regularly packed
Defective sleepers should be replaced immediately
Worn-out rails should be replaced
Kink or fracture rails should be replaced
Fastening should be tightened and oiled
Gauge should be checked and corrected
Ensure that both the rails are at same level
Maintain track drainage properly
Oiling and greasing of fishplates regularly
Flanges and check rails should be kept free from dust
Maintenance of Bridges:
Proper embankment should be provided near the
bridge
Avoid scouring near abutments and piers
Flood control measures should be taken near the
bridges
Riveted joints should be inspected periodically
Bed blocks should be checked regularly
Steel bridges should be painted regularly
Bearings of the girders should be oiled regularly
Masonry works should be inspected regularly
Maintenance of rolling stock:
Lubrication of all reciprocating parts and bearings
Wornout parts should be replaced the rolling stock
It is necessary to clean the different parts every day
All axles which have run 3,22,000Km should be
replaced
A passenger vehicle used for 30years should be
dismantled and re-assembled
The locomotive boilers have to be carefully
maintained and removed every 15 years