MODULE-II INFRASTRUCTURE ENGINEERING BTCVC702

Prepared by-
Prof. Basweshwar S.J.

MODULE-2
Points and Crossings:
Standard types, Design of simple turnout, various types of Junctions,
Stations and Yards: Purpose, Location, Site selection, general layouts of
Terminus and Junction, Signaling and Interlocking, Construction and
Maintenance of Track, Modern trends in Railways
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2. Points and Crossings:
• Points and crossings are provided to help transfer railway vehicles from one
track to another.
• The tracks may be parallel to, diverging from, or converging with each other.
• Points and crossings are necessary because the wheels of railway vehicles are
provided with inside flanges and, therefore, they require this special
arrangement in order to navigate their way on the rails.
• The points or switches aid in diverting the vehicles and the crossings provide
gaps in the rails so as to help the flanged wheels to roll over them.
• A complete set of points and crossings, along with lead rails, is called a
turnout. Prepared by-

2. Points and Crossings:
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2.1 Standard types
• Turnouts and crossovers, including switches, frogs, guard rails, stock rails, and closure rails; rail fastening
assemblies unique to turnouts; and miscellaneous components associated with turnouts, including switch
rods and gauge plates.
• Crossover tracks, double crossovers including the central crossing frogs or diamond area, and single and
double slip switches are included in this category.
• The cross ties to support turnouts and crossovers can also be considered part of special track work,
especially concrete switch ties, which require far more design and fabrication effort than ordinary timber
switch ties.
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• Points (switch rails or point blades) are the
movable rails which guide the wheels towards
either the straight or the diverging track.
• Stock rails are the running rails immediately
alongside of the switch rails against which the
switch rails lay when in the closed position.
• Frog is a component placed where one rail
crosses another, refers to the crossing point of
two rails.
• Closure rails are the straight or curved rails
that are positioned in between the heel of
switch and the toe of frog.
• Guard rail (check rail) is a short piece of rail
placed alongside the main (stock) rail opposite
the frog.
• Heel block assemblies are units placed at the
heel of the switch that provide a splice with the
contiguous closure rail and a location for the
switch point rail to pivot at a fixed spread
distance from the stock rail.
• Switch point rail stops act as spacers between
the switch point rail and the stock rail.
• A switch operating device moves switch rails.
Switch rails can be thrown (moved) from one
orientation to another by either a hand-
operated (manual) switch stand or a
mechanically or electro-mechanically (power-
operated) switch machine.
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Turnout Types
• A single crossover consists of two turnouts
positioned in two tracks that allow the vehicle
to go from one track to another.
• The two tracks are usually, but not always,
parallel, and the turnouts are usually identical.
• A pair of single crossovers—one right hand and
one left hand—that are arranged sequentially
along the tracks is called a universal crossover.
• A double crossover sometimes called a scissors
crossover consists of two crossovers of opposite
hand orientation superimposed upon each
other.
• In addition to the four turnouts involved, a
track crossing diamond is needed between the
two main tracks.
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Turnout Types
• Track crossings, as the name implies, permit
two tracks to cross each other.
• Track crossings are often called either crossing
diamonds or simply diamonds, due to their
plan view shape.
• Lapped turnouts can be used to achieve a more
compact track layout in constrained locations.
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2.2 Design of simple turnout
• The new track geometry of turnouts is usually set in the route plan in height and direction.
• The marking out is done by the surveying department.
• The marking out (to ensure the target geometry) by wooden poles is particularly important.
• It is necessary to ensure that the piles are put in sufficiently deep that they do not get damaged or buried
during the work.
• A so-called turnout sketch is the basis for the procurement, construction and installation of turnouts and
crossings.
• The factory prepares a turnout laying plan on the basis of the turnout sketch for each turnout and
crossing.
• The sequence of the individual parts when building a simple turnout within the framework of the
construction planning is set in relation to the selected turnout rework procedure, among other things, the
space available for assembly and disassembly.
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2.3 Various types of Junctions
• A junction, in the context of rail transport, is a
place at which two or more rail routes converge
or diverge.
• This implies a physical connection between the
tracks of the two routes (assuming they are of
the same gauge), provided by points) and
signaling.
• Junctions are important for rail systems, their
installation into a rail system can expand route
capacity, and have a powerful impact upon on-
time performance.
Measures to improve junction capacity-
• The capacity of the junctions limits the
capacity of a railway network more than the
capacity of individual railway lines.
• The capacity of a railway junction can be
increased with improved signaling
measures, by building points suitable for
higher speeds, or by turning level junctions
into flying junctions.
• With more complicated junctions such
construction can rapidly become very
expensive, especially if space is restricted by
tunnels, bridges or inner-city tracks.
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2.3 Various types of Junctions
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2.4 Stations
• A train station, railway station, railroad station or depot
is a railway facility or area where trains regularly stop to
load or unload passengers or freight or both.
• It generally consists of at least one track-side platform
and a station building (depot) providing such ancillary
services as ticket sales, waiting rooms and
baggage/freight service.
• If a station is on a single-track line, it often has a passing
loop to facilitate traffic movements.
• The smallest stations are most often referred to as
"stops" or, in some parts of the world, as "halts" (flag
stops).
• Stations may be at ground level, underground or
elevated.
• Connections may be available to intersecting rail lines or
other transport modes such as buses, trams or other
rapid transit systems. Prepared by-

2.4 Stations
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2.4 Stations
Purpose of a railway station:
• For exchange of passengers
• For exchange of goods.
• For control of train movements
• To enable the trains on a single line track to cross
from opposite directions.
• To enable the following express trains to overtake
• For taking diesel or coal and water for locomotives
• For detaching engines and running staff
• For detaching or attaching of compartments and
wagons.
• For sorting of bogies to form new trains, housing
of locomotive in loco sheds.
• In emergencies in ease of dislocation of track due
to rains, accidents etc...
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2.4 Stations
Station :
Means any place on a line of railway at which traffic
is dealt with, or at which an authority to proceed is
given to the driver of the train under the system of
working.
Block stations :
Block stations are those at which driver must obtain
an authority to proceed under the system of working
to enter the block section with his train.
Non-Block station :
These are outlets opened for commercial purpose
and no block working is carried here. To cope up with
different working conditions stations are categorized
into various classes.
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2.4 Stations
Class A Station :
Where line clear may not be given for a train
unless the line on which it is intended to receive
the train is clear for at least 400 Mts., beyond the
Home signal or up to the starter.
Class B Station :
Where line clear may be given for a train before the line
has been cleared for the reception of the train within the
station section.
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2.4 Stations
Class C Station :
At which no train is booked to stop. This includes IBS, line
clear may not be given for a train, unless the whole of the
last proceeding train has passed completely at least 400
Mts. beyond the Home signal and is continuing its journey.
Class D Station :
Situated between two consecutive block stations and do
not form the boundary of any block section.
Minimum signaling equipment required for each class of
station
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2.5 Yards
• An area consisting of a
network of railway tracks,
sidings, and sheds for
storing, maintaining, and
joining engines and carriages.
• A yard is defined as a system
of tracks laid within definite
limits for various purposes
such as receiving sorting and
dispatch of vehicles.
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Passenger yards Goods yards
Function of passenger yard is to
provide all the facilities for the
safe movement of passengers.
Facilities in passenger yards
• Booking office, enquiry
office, luggage booking
room, cloak room and
waiting room for passengers
• Parking space for vehicles
• Signals for reception and
dispatch of trains
• Platforms and sidings for
shunting facilities
• Facilities for changing
batteries
• Facilities for passing a
through train
• Washing lines, sick lines
facilities
A goods station (also known as a
goods yard, goods depot or freight
station) is, in the widest sense, a
railway station which is exclusively
or predominantly where goods (or
freight) of any description are
loaded or unloaded.
Facilities at Goods Yards
• These are provided for receiving,
loading and unloading of goods.
• Approach road for movement of
goods
• Sufficient number of platforms
for loading and unloading
• Sufficient number of godowns
• Booking office
• Cart weighing machine
• Cranes for loading and
unloading
• Vacuum testing machine
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Marshalling yards
A yard is a classifying and distributing machine with facilities for
receiving, sorting and dispatching wagons to their various
destinations after the prescribed attention.
Factors for the efficient functioning of marshalling yards-
• Shunting operations should not disturb the regular trains
• Should be kept parallel to the running trains
• Movement of wagons in one direction only
• Repair facilities should be provided on one or more sidings
• Connected to all important railway stations
• Goods yard should be nearer to the marshalling yard.
(i) Flat yard
• Flat yards are constructed
on flat ground, or on a
gentle slope.
• Freight vehicles are pushed
by a locomotive and coast
to their required location.
(ii) Gravity yard
• The whole yard is set up on
a continuous falling
gradient and there is less
use of shunting engines.
(iii) Hump yard
• A hump yard has a
constructed hill, over which
freight cars are shoved by
yard locomotives, and then
gravity is used to propel
the cars to various sorting
tracks.
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Locomotive yards
This is the yard which houses the
locomotives for various facilities such as
watering, fueling, cleaning, repairing,
servicing etc.
Requirements-
• Should be located near the passenger and
goods yards
• Water column
• Engine shed, Ash pit, inspection pit,
repair shed, turn table
• Hydraulic jack for lifting operations
• Over head tank and loco well
• Sick siding
• Place for future expansion
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Locomotive yards
Requirements-
• Should be located near the passenger and
goods yards
• Water column
• Engine shed, Ash pit, inspection pit,
repair shed, turn table
• Hydraulic jack for lifting operations
• Over head tank and loco well
• Sick siding
• Place for future expansion
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2.5 Signaling and Interlocking
 Railway signalling is a system used to control
railway traffic safely, essentially to prevent
trains from colliding.
 Signaling consists of the systems, device and
means by which trains are operated efficiently and
tracks are used to maximum extent, maintaining
the safety of the passengers, the staff and the
rolling stock.
 It includes the use and working of signals, points,
block instruments and other equipments.
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2.5 Signaling and Interlocking
OBJECTIVES-
• To provide facilities for the efficient moving of
trains.
• To ensure safety between two or more trains which
cross or approach each other's path.
• To provide facilities for the maximum utility of the
track.
• To provide facilities for safe and efficient shunting
operations.
• To guide the trains movement during maintenance
and the repairs of the track.
• To safeguard the trains at converging junctions
and give directional indications of diverging
junctions. Prepared by-

Classification of Signaling
(a) Stop signals or semaphore type signals (b) Warner signals
• One of the earliest forms of fixed railway signal is
the semaphore.
• These signals display their different indications to
train drivers by changing the angle of inclination of a
pivoted 'arm‘.
• The stop position is the normal position and it is
said to be ON position.
• The arm can be lowered at an angle of 400 to 600
with horizontal and is said to be OFF position.
• The warner signal is similar to semaphore
signal in shape except a v-notch at free end,
i.e. The movable arm is fish tailed as shown.
• The white band is also of v- shape.
• The warner signal is placed on the same post
of the semaphore signal 1.8 to 2.1m below
the semaphore signal.
• The warner signal is painted yellow and
exhibits yellow or amber colour at night
instead of red colour.
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Classification of Signaling
(c) Disc or ground signals (d) Colored light signals
• These signals are used for shunting operations in
station yards.
• They are of the shape of a circular disc with a red
band on a white back ground.
• The disc can revolve in a vertical plane by
pulling the lever by hand.
• Two holes are provided, one for red lamp and the
other for the green lamp.
• When the red band is horizontal or shows red
light at night it indicates ―STOP
• When the red band is inclined at 45 degree or
shown green light at night indicates
―PROCEED.
• Semaphore signals are being replaced by high
intensity beam colour light signals both during
day and night.
• In case of colour light signals, the normal
position is to indicate ―PROCEED (i.e., shows
green light)
• When the section is blocked, it automatically
indicates ―STOP or ―DANGER (i.e., shows red
light)
• In India these signals are used on urban and
sub- urban sections with heavy traffic.
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Locational Characteristics of Signals
(i)Reception signals
(a) Outer signal (b) Home signal
• This is the first stop signal which indicates the entry
of the train from block to the station yard.
• It should be placed at an adequate distance (0.54km for
BG and 0.4 km for MG).
• It has one arm but may have a warner signal on the
same post nearly 2m below it.
• In the Stop position the driver must bring his train to
a stop at a distance of about 90m before the outer
signal and then proceed to the home signal with
caution.
• If it is in the Proceed position then the driver can take
the train at speed, assuming that home signal is also in
the proceed position.
• Due to its location at the door of station, it is termed
as Home signal.
• The home signal has bracketed arms to indicate
which line is to be used.
• The function of home signal is to protect the sidings
already occupied.
• It is located at not more than 180m from the start of
points of switches.
• Home signals carry as many arms as the number of
diverging lines.
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Locational Characteristics of Signals
(ii) Departure signals
(a) Starter
• It marks the limit up to which trains stopping at a station
should come to a stand.
• The starter is the last stop signal at a station.
• It controls the movements of the trains when they depart
from the stations.
• No train can leave the station unless the starter signal
shows the ―PROCEED position.
• Besides the starter signal for each of the station lines from
which trains starts, an advance starter may also be
provided.
• The advance starter becomes the last stop signal at the
stations where is provided.
• It is an indication for the train having left the station.
(b) Advance Starter
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Interlocking
• In railway signaling, an interlocking is an arrangement of signal
apparatus that prevents conflicting movements through an
arrangement of tracks such as junctions or crossings.
• An arrangement of signals and signal appliances so
interconnected that their movements must succeed each other in
proper sequence".
• In general terms an interlocking is a location where plain track
ends and track work with points and crossings complicate train
movements. These areas are likely to be:-
• Junctions where two or more main lines meet.
• Complex yards or sidings are encountered. These may be at
larger towns or depot facilities.
• An interlocking provides for complex train movements and
shunting of trains.
• It provides for the protection of multiple train movements
within a localized area. Prepared by-

Interlocking
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Interlocking
• The signals and points are operated by means of
levers.
• Levers are located at ground level or platform
level or in an elevated structure called signal
box or signal cabin.
• Interlocking is done by grouping levers at one
point.
• The levers are painted for easy identification.
• There are three methods of interlocking
• Tappets and lock system
• Key system
• Route relay system.
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Interlocking
There are three methods of interlocking
Tappets and lock system Key system Route relay system
• This method is useful when levers are to
be interlocked so as to prevent
conflicting movement.
• The tappers are of steel sections. 38mm
X 16mm with suitable recesses and
notches. They are attached to the levers.
• The locks are also of steel with shapes to
suit the recesses in the tappers.
• The lock move at right angle to the
tappers.
• In this system, the points and signals
for movements of trains are
electrically operated.
• This is the mode and sophisticated
system of interlocking.
• Due to this system there is a
considerable saving of man power
and maintenance expenditure of
cabins.
• This is the simplest method of
interlocking. The key locks are
manipulated in this system
• The principle of this system is
to provide two locks which are
worked by a single key.
• With drawl of the key locks the
signal in the horizontal position
and the points in the normal
setting for the main line.
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CONTROL OF TRAIN MOVEMENTS-
It is quite essential that movements of trains on particular tracks should be safe and for this
purpose various methods are found out.
(i)Following trains system
(ii)Absolute block system
(iii)Automatic signaling
(iv)Pilot guard system
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(i)Following trains system (ii)Absolute block system
• Used in case of emergencies such as failure of
telegraph and telephone systems.
• In this method, a fixed interval of time is
maintained between the departure of one train
and the departure of the next train along the same
time.
• This fixed interval is worked out in such a way that
sufficient distance or headway in maintained
between the tail of the first train and the head of
the next following train.
• The principle of the absolute block system of
railway signaling is to ensure the safe operation
of a railway by allowing only one train to
occupy a defined section of track at a time.
• Instead of a fixed interval of time between
successive trains, a varying interval may be kept
depending on the time, actually taken by
particular trains.
• It is a space interval system rather than a fixed
interval system.
• The electric telegraph provided the ability for
signalmen to communicate with each other and
provided the basis for the absolute block system
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(iii)Automatic signaling (iv)Pilot guard system
• In order to avoid accidents, automatic
signaling has been found out.
• In this signals are operated by trains
themselves.
• An electric current is conveyed through the
track when a train occupies that particular
track and this current puts the signal at
danger position until the train has gone far
ahead so as to require no further protection.
• Used on certain occasions such as breakdown of
telephone and telegraph system on a single line
and one track of a double line being out of order.
• In this system, a pilot proceeds by one train to
the station ahead and then he returns by a train
running in the opposite direction.
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Automatic Block System-
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2.6 Construction of Track
1. Telescopic Method of Construction 2. Tram line Method of Construction 3. Mechanical Methods
• In this method of construction
rails, sleepers, fastenings are
unloaded from the material
train as closer to rail head as
possible.
• The sleepers are carried by
cart or by men along the
adjoining service road and
spread on the ballast.
• The rails are then carried on
pairs to the end of last pair of
connected rails and linked.
• This method is used where
tram carrier are installed for
carrying earthwork or in rainy
season due to difficulty in
movement of cart.
• The basic difference between
Telescopic and Trame line lies
in the conveyance and
spreading of sleepers.
• This method is extensively used
by special machines.
• There are two types of machines
available-
• In the first type track material
carried by the material train and
delivered at rail head and laid in
the required position by means of
projecting arm mounted on the
truck nearest to the rail head. The
material train moves forward on
the assembled track and operation
repeated.
• In the second method a long
cantilevered arm projecting
beyond fitted on the wagon. A
panel of assembled track consisting
pair of rails with number of
sleepers on the ballast layer. It is
lowered by the jib at the required
position and connected to the
previous panel. The train moves on
and operation repeated.
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2.7 Maintenance of Track
• Track geometry is three- dimensional
geometry of track layouts and associated
measurements used in design, construction
and maintenance of railroad tracks.
• The subject is used in the context of
standards, speed limits and other
regulations in the areas of track gauge,
alignment, elevation curvature and track
surface.
• Although, the geometry of the tracks is
three-dimensional by nature, the standards
are usually expressed in two separate
layouts for horizontal and vertical.
Existing System of track Maintenance
1. Manually
2. Three tier system of maintenance
• The track should be maintained either by
conventional system of track maintenance or by
three – tier system of track maintenance.
• In both the systems, track requires to be overhauled
periodically with the object of restoring it to best
possible condition, consistent with its
maintainability.
• Periodicity of overhauling depends on several
factors, such as type of track structure, its age,
volume of traffic, rate of track deterioration,
maximum permissible speed, system of traction,
condition. Prepared by-

(1) 3- tier system of track maintenance
shall be adopted on sections nominated
for mechanized maintenance. This shall
consist of the following 3 tiers of
maintenance-
(i) On track machines
(ii) Mobile maintenance units
(iii) Sectional gangs
(B) Three tier system of track maintenance: -
(2) Large track machines for track
maintenance include tie- tamping
machines for plain track and points and
crossings, shoulder ballast cleaning
machines, ballast-cleaning machines,
ballast regulating machines and
dynamic track stabilizers.
These machines shall be used as per the
various instructions issued in Indian
Railways Track Machines Manual.
These machines shall be deployed to
carry out the following jobs.
(a) Systematic tamping of plain
track as well as points and
crossings.
(b) Intermediate tamping of plain
track as well as points and
crossings.
(c) Shoulder ballast cleaning.
(d) Ballast profiling / redistribution.
(e) Track stabilization.
(f) Periodical deep screening.
(3) Mobile Maintenance Units-
(a) The mobile maintenance units
(MMU) shall consist of two groups-
(i) MMU-I one for each PWI’s section
(ii) MMU-II one for each sub division.
(b) The functions of MMU shall be as
below:
1.Track Relaying
Activities and Existing system of
Relaying.
2. Turnout relaying
At present both these activities are
performed both manually and by
machines.
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2.8 Modern trends in Railways
• Rapid transport is a type of high-capacity public
transport generally found in urban areas.
• Unlike buses and trains, rapid transport systems
operate on an exclusive right-of-way which is
usually grade separated in tunnels or elevated
railways.
• Metro is the most common term for underground
rapid transport systems.
• Rapid transport is used in cities and metropolitan
areas to transport large numbers of people often
short distances at high frequency.
• The extent of the rapid transport system varies
greatly between cities, with several transport
strategies.
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2.8 Modern trends in Railways
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MODULE-II INFRASTRUCTURE ENGINEERING BTCVC702

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