Point and Crossings are peculiar arrangement used in permanent way (railway track) to
guide the vehicle for directional change. Broadly point and crossing assembly consists
of three main components namely
Point,
Lead and
Crossing element. A point consists of one pair of tongue rails and
Stock Rails with necessary fittings.Crossing is a device in the form of V-piece
introduced in the track to permit movement of wheel flange at the inter section of two
running lines.It has gap over which the wheel tread jumps.The track portion between
point and crossing is is called lead.
The points and
crossing are the vital components of track asset; necessary for diversion of traffic
from one track to another track, such diversion may be necessitated for giving
precedence to faster trains in the same direction, giving passage to a train moving in
the opposite direction or for connecting places not on the direct line of track. Hence
the design, laying and maintenance of the points and crossing have a significant
influence throughout the section.
Constituents of the points and crossing
The switch assembly, the crossing assembly and the lead portion beyond the turnout,
turn-in- curve is also important assembly.
- Turnout- The term denotes points and
crossing with the lead rails.
- Tongue rail - It is tapered moveable
rail, connected at its thickest end to running rail.
- Stock rail – It is the running rail,
against which a tongue rail functions.
- Switch – A pair of tongue with stock
rail with necessary connections and fittings.
- Points – A pair of tongue rail with
their stock rails are termed as points.
- Crossing – A crossing is a device
introduced at the junction where two rails cross to permit the wheel flange of
railway vehicle to pass from one track to another track.
- Heel of switch – It is an imaginary
point on the gauge line midway between the end of lead rail and the tongue
rail in case of loose heel switches In case of fixed heel switches, it is a
point on the gauge line of tongue rail opposite the centre of heel block.
- Lead – The track portion between heels
of switch to the beginning of crossing assembly is called lead. ix) Turn – in
– curve: The track portion between the heel of crossing to the fouling marks
is called turn – in – curve.
