Apparatus, methods and communication systems for providing relatively constant warning time at highway-rail grade crossings with rail-based communications

摘要

Apparatus, methods and a communication system for providing relatively constant warning time at a rail grade crossing for trains with prediction of the approach of a train from a remote controller via rail-based communications to a crossing controller. A first communication signal is generated when a prediction occurs and a second communication signal is generated for slower moving trains, with the second signal temporarily overriding the first signal to provide relatively constant warning time at the crossing. Cancellation timers with timing intervals are used to resolve situations where the train does not enter the approach or where the train leaves by way of a switch or backs out. Directional logic is used to determine the direction of movement of the train and, in conjunction with cancellation timers, causes the warning devices to be activated when the timers expire.