To prescribe the rules for identifying and responding to unreliable track-circuit operation in the Network.
Identifying unreliable track‑circuits
Qualified Workers must report track-circuits suspected of being faulty to the Signaller.
The Signaller must treat the operation of the reported track-circuits as unreliable.
Intervals between train movements
Signallers must treat the operation of track-circuits that have not been travelled over by rail traffic for 72-hours or more as unreliable.
The responsible Signal Engineer may specify a period longer or shorter than 72-hours for designated portions of track.
Responding to unreliable track‑circuits
Rail traffic detection failure
Track-circuit operation must be treated as failed and in an unsafe condition if it fails to provide an indication when a train, or a track vehicle listed in the Train Operating Conditions (TOC) manual as operating track-circuits, is on the track-circuit.
Signallers who become aware that track-circuit detection of rail traffic might have failed must:
- set controlled signals allowing entry to the affected blocks at STOP and apply blocking facilities, and
- arrange for the Signals Maintenance Representative to be told about the unreliable track-circuits, and
- make sure that signalling equipment affected by unreliable track-circuits is not used before it is tested and certified as working correctly by the Signals Maintenance Representative, and
- tell the Network Controller, and
- block work rail traffic.
False detection of rail traffic
Track-circuit detection is treated as false if it indicates that the track-circuit is occupied without rail traffic being present.
Signallers who become aware that track-circuits are providing a false indication of the presence of rail traffic must arrange for the Signals Maintenance Representative to certify the track-circuits as working correctly.
Until the track-circuits have been certified as working correctly, rail traffic must be worked in accordance with: