Ballast

Ballast is the granular material usually broken stone or any other suitable material which is spread on the top of railway formation and around the sleepers.

FUNCTIONS OF BALLAST:

To hold the sleepers in position and preventing the lateral and longitudinal movement.
To distribute the axle load uniform from sleepers to a large area of the formation.
To provide elasticity to the track. It acts as elastic mat between subgrade and sleepers.
To provide easy means of maintaining the correct levels of the rails in a track.
To drain rainwater from the track.
To prevent the growth of weeds inside the track.

CHARACTERISTICS OF GOOD BALLAST:

It should have sufficient strength to resist crushing under heavy loads of moving trains.
It should be durable enough to resist abrasion and weathering action.
It should have a rough and angular surface so as to provide good lateral and longitudinal stability to the sleepers.
It should have good workability so that it can be easily spread of formation.
It should be cheaply available in sufficient quantity near and along the track
It should not make the track dusty or muddy to its crushing to powder under wheel loads.
It should allow for easy and quick drainage of the track.
It should not have any chemical action on metal sleepers and rails.