edwin_m
Veteran Member
Track circuit currents are typically in the region of one amp. A train on DC can send several thousand amps back through the same rails. So clearly even a tiny component at the frequency of the track circuit is going to be a concern.
More modern track circuits have several signals going out at once rather than a simple AC current, and the receiver has to "see" all these to declare the track not occupied. This makes them less prone to wrong side failure but a right side failure will happen if interference from a train cancels out any of these signals. Hence the interference is no longer an immediate safety issue but would be a problem for reliability (and resulting degraded working would introduce some hazard) if it happened often.
More modern track circuits have several signals going out at once rather than a simple AC current, and the receiver has to "see" all these to declare the track not occupied. This makes them less prone to wrong side failure but a right side failure will happen if interference from a train cancels out any of these signals. Hence the interference is no longer an immediate safety issue but would be a problem for reliability (and resulting degraded working would introduce some hazard) if it happened often.