What does an illuminated indication light in a track circuit signify?

An illuminated indication light in a track circuit signifies an occupied track circuit. This means that the track section is currently occupied by a rail vehicle, which could include trains or maintenance vehicles. The purpose of the indication light is to provide visual confirmation to operators and other personnel that the specific section of track is in use and should be treated accordingly to ensure safe operations.

When a track circuit is occupied, the circuit detects the presence of a train due to the change in electrical resistance caused by the train's wheels and axles completing the circuit. This is crucial for safety in rail operations, as it helps prevent accidents such as collisions and ensure that signaling systems work as intended.

Other indications in the context of track circuits, such as non-occupied, ghost circuits, or power failures, relate to different operational statuses but do not signify the physical presence of a train on the tracks. Understanding this distinction is vital for ensuring safety and proper response when managing rail traffic.