Multi relay track circuit

[Peter]

Do you mean
a) a track circuit having a second relay at the feed end as well as the main relay at the other end, or

Yes, Please explain about item (a)

Where there are problems which give poor shunting characteristics or leakage through the ballast from other track circuits give the risk that the relay could remain energised when a legitimate train shunt is at the opposite end of the track, a second relay is placed at the feed end as well and either TR down will occupy the section.