What is a Railway Sleeper?

Sleepers are vital components which are normally placed transverse to the rails. The rails are supported and set to transmit the loads from the rails to the ballast and the sub grade.

The purpose of sleepers: Retaining rails to proper gauge and alignment. Transmitting load uniformly from rails to larger area of ballast.

Providing elastic medium among rails and ballast.
Providing longitudinal and lateral strength.
Necessity of sleepers
The applicable sleepers should be cheap and they should contain least possible preliminary & maintenance cost.
Setting and detaching of fastenings are simple.
Adequate bearing area.
Maintenance and gauge adjustment are simple.
Track circuiting (electric insulation) can be done.
Capability of withstanding shocks and vibrations.

The following types of sleepers are available :-

Timber or wooden sleepers - Metal sleepers, Cast Iron sleepers

Steel sleepers - Concrete sleepers, Reinforced concrete sleepers, Pre-stressed concrete sleepers

Also Read: How to calculate the distance between the passenger and train

In this civil engineering article, detail information is provided on concrete sleepers.

Concrete sleepers: Benefits

Longer longevity (40 to 60 years).
Superior strength.
Less damage is occurred at the time of handling/transmit.

Simple to retain gauge.
Good resistance capacity against fire or corrosion.
No chance of being theft.
No scope for gauge expansion.
They are not affected with vermin and natural decay.
Track - circuiting process is not complicated.
Sleepers - Spacing & Density
The effective span of the rail over the sleepers is decided by the distance among two nearby sleepers.

It is based on bearing the axle load & lateral thrust.
The number of sleepers in a track is specified by the number per rail length.
More number of sleepers can maintain strong lateral strength to the track.
The number of sleepers per rail differs in India from M+4 to M+7 for main track, where M denotes length of rail in meters.