Track drainage can be defined as
the interception, collection, and disposal of water from the track. It is
accomplished by introducing a proper surface and sub-surface drainage system.
This subject has been discussed in detail in Chapter 19.
Maintenance of Track in Track-circuited
The length of track connected by
an electric circuit to the signal cabin, block telegraph apparatus, etc.
required for indication of light is called a track circuit. Thus, a track
circuit functions to indicate whether the track is occupied or not.
Special precautions are necessary
in the maintenance of track-circuited lengths as accidental short circuiting of
a circuit in the track may cause serious delay in traffic. Some of the
noteworthy points in this regard are as follows.
permanent way inspector should instruct the staff not to touch or place any
tool or metal object across the two rails in the track, as this will cause
short circuiting of the track circuit.
gauges, straight edges, and trolleys used in the track-circuited length should
ballast must be clean throughout the track-circuited length and care should be
taken to see that the ballast is kept clear of the rails and rail fastenings.
The clearance from the foot of the rail must not be less than 40 mm.
drainage of the track should be ensured to avoid the flooding of the tracks
during the rains. Ashpits, water columns, and platform lines should be
Track-circuited sections are
electrically insulated from the rest of the track by insulation joints that are
present on either side of these sections. The most common type of insulation
joints are as given below.
(a) One type
of insulation joint is made up of a planed fish plate fitted with fibre or nylon
insulation consisting of ferrules or bushes for the fish bolts, side channels
between the fish plates and rails, and end posts between the rail ends.
(b) The other
type of insulation joint consist of rubber-coated fish plates. There are two
designs of this insulation joint. In one design, the fish plate is coated with
synthetic rubber or nylon on the fishing surface. In the other design, the fish
plates are completely coated with rubber or nylon, including the bolt holes.
These insulation joints were tried in the field but proved unsuccessful owing
to the fact that the rubber coating gets cut easily.
insulated glued joints have been developed using resin adhesives. These joints
consist of web-fitting type of fish plates glued to the rails using a high
polymer adhesive and bolted with high tensile bolts. Insulation is provided by
special insulating side channels, bushes, and posts made out of fibreglass
cloth. These joints do not exhibit the movement and hence all maintenance
problems are completely eliminated.