Railroad traffic control signaling system

Abstract From the Canadian patent

Separate traffic and block clear indication line circuits control either direction train movements through a stretch of track under cab signal indications without intermediate wayside signals. Reversible phase sensitive track circuits provide train detection and cab signal energy. A block clear opposing, locking repeater relay and a traffic route request relay at the selected entrance end of the stretch control the traffic line circuit to initiate traffic reversal operations. The magnetic stick traffic relays are shunted by a back contact of a neutral line relay to protect against lock out of the traffic line circuit by external voltage surges. The direction of the block clear line circuit …