scope:

There are two methods of TAD deployment, permanently wired in to the track circuit to disconnect its circuit (like a track circuit interrupter), or wired separately to the track circuit with its own power supply and applying an electrical shunt directly to the rails (like a TCAID). All types of conventional track circuit and traction area are included in this application, though the electrical shunt type cannot be used on electrified lines and the method of wiring in the permanently wired type may vary according to track circuit type.

Purpose

This Product Specification gives the requirements for a device that detects electrical noise from a train whilst it occupies a specific section of track, and then applies a shunt or disconnection to the track circuit containing that section of track.