turnouts in railways

UNDER THE GUIDANCE OF
V. MADDILETY RANGADU, M. TECH
PRESENTED BY
G. SRINIVASULU
14BC1A0124
1

 1. INTRODUCTION
 2. COMPONENT PARTS OF TURNOUTS
 3. OPERATION
 4. CLASSIFICATION OF TURNOUTS
 5. SAFETY
 6. CONCLUSION
 7. REFERENCES
2

 A railway switch or turnout is a mechanical installation enabling railway
trains to be guided from one track to another at a railway junction.
 It consists of the pair of linked tapered rails known as the ‘points’ lying
between the diverging outer rails, can be moved laterally in to one of two
positions to direct a train coming from the point blades towards the straight
path or the diverging path
 A train moving from the narrow ends towards the point blades is said to be
executing a facing point movement, and the train coming from either of the
converging direction passing through the narrow points is said to be tailing
point movement
 A turnout generally consists of a straight through track and a diverging track.
 Right hand turnout have a diverging track to the right of the track and the
left hand turnout have a diverging track to the left of the track
3

 POINTS
 STOCK RAILS
 FROG
 CLOSURE RAILS
 GUARD RAILS
 HEEL BLOCK
 SWITCH OPERATING DEVICE
4

 Switch rails or Point
blades are the movable
rails which guide the
wheels towards either the
straight or the diverging
track.
 They are tapered on most
switches, but on stub they
have square ends
5

 Stock rails are the running
rails immediately alongside
of the switch rails against
which the switch rails lay
when in the closed
position. The stock rails are
otherwise ordinary rails
that are machined, drilled,
and bent as required to
suit the design of the
turnout switch and the
individual switch point
rails
6

 The frog, also known as the common
crossing, is the crossing point of two
rails. This can be assembled out of
several appropriately cut and bent
pieces of rail or can be a
single casting of manganese steel. On
lines with heavy use the casting may
be treated with explosive shock
hardening to increase service life
7

 Closure rails are the
straight or curved rails that
are positioned in between
the heel of switch and the
toe of frog
8

 Guard rail (check rail) is a short piece of rail
placed alongside the main (stock) rail opposite the
frog. These exist to ensure that the wheels follow
the appropriate flangeway through the frog and
that the train does not derail
9

 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
10

 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. In both cases, the operating devices are
positioned at the beginning of the turnout opposite
the switch-connecting rods near the point of the
switch rails.
11

 When the wheels reach the switch, the wheels are guided along the route
determined by which of the two points is connected to the track facing the
switch.
 If the left point is connected, the left wheel will be guided along the rail of that
point, and the train will diverge to the right. If the right point is connected,
the right wheel's flange will be guided along the rail of that point, and the
train will continue along the straight track.
 A mechanism is provided to move the points from one position to the other
 some switches are still controlled by a human operator. However, most are
now operated by a remotely controlled electric motor
12

 Single Crossover:
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.
13

 Double 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. A double crossover is typically used only
when it is necessary to be able to switch from both
tracks to the other in either direction, but there is
insufficient space to install a universal crossover.
14

 Track Crossing:
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
15

 SLIP SWITCH
A single slip switch works on
the same principle as a
double slip but provides for
only one switching
possibility. Trains
approaching on one of the
two crossing tracks can
either continue over the
crossing, or switch tracks to
the other line
16

 Lapped Turnouts:
Lapped turnouts can be used to achieve a
more compact track layout in constrained
locations. In a lapped turnout, as seen in
following picture, the switch rails for a
second turnout will be placed between the
switch and the frog of the initial turnout.
This introduces a third frog where a
closure rail of the first turnout crosses a
closure rail of the second turnout
17

 Reversing the points under a moving train will almost always derail the train
 Points might move due to the extreme forces exerted by a passing train
 Interlockings that allow signals only to be cleared when switches are set
correctly
 Track circuits to prevent reversing when a passing train is detected
 Electrical devices should be checked frequently
18

 On a lightly-trafficked line, with careful maintenance it can last for 25 years,
but at a busy junction on a main line it may have to be replaced every 12
months. The work is usually carried out at night to avoid disrupting the
timetable
 . When travelling through a turnout at speed, the safety of a train depends on
accurate alignment of the switch-blades and associated gear. A rigorous
maintenance regime is essential, and it doesn’t necessarily involve high
technology
 . A set of turnouts may be trial assembled beforehand off site, to check that
everything fits
19

 Physicist Richard Feynman explains how a train stays on the tracks. BBC TV
'Fun to Imagine' (1983)
 Rules 8.9, 8.15, and 8.18, General Code of Operating Rules, Fifth Edition. (c)
2005 General Code of Operating Rules Committee
 Points and Crossings from Vossloh Cogifer
 "63 FR 39343 – Automatic Train Control and Advanced Civil Speed
Enforcement System; Northeast Corridor Railroads". Federal Railroad
Administration. Retrieved 21 October 2012
 Information on winter operation by dutch infrastructure manager Prorail (in
dutch)
 Meyers, Marc A. (1994). Dynamic behavior of materials. New York: John
Wiley. pp. 5; 570. ISBN 978-0-471-58262-5
 "Scene of the Accident". The Argus. Melbourne: National Library of Australia.
29 January 1906. p. 7. Retrieved 20 July 2011 20

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