Electric Traction | What are track circuits? State any two functions of it.

Track Circuits: 

A track circuit is an electrical circuit used to detect the presence / absence of a train on rail tracks, which is further used to inform signalers for controlling the relevant signals. 

Functions of track circuits:

1) It prevents the second train to come on that portion of the track on which the first train is already present.

2) Due to bridges, buildings, long steep curvatures, and single is out of view of  signal man, track circuit helps to indicate the present of train on that section.

3) It indicates presence of train on any particular sections.

4) It indicates absence of train on any particular sections.