RAILWAY ROAD CROSSING WARNING SYSTEM WITH SENSING SYSTEM ELECTRICALLY-DECOUPLED FROM RAILROAD TRACK

摘要

A railway road crossing warning system (10) including a railway roadcrossing control unit (18) that may be selectively set to a primary or asecondarymode of operation is provided. In the primary mode of operation, the railwayroadcrossing control unit is responsive to a primary activation signal (21)received from aprimary activation-signal source (22), such as a positive train control (PTC)system.In the event the primary activation signal from the primary activation-signalsource isnot available, railway road crossing control unit (18) is set to the secondarymode ofoperation, where the railway road crossing control unit is responsive to oneor moresignals (25) received from a secondary activation-signal source (26) includingarailway-vehicle sensing system (28) electrically-decoupled from a railroadtrack (12).Disclosed embodiments maintain operational robustness in the presence ofchangingweather and avoid variable electrical ballast conditions that otherwise coulddevelopacross the rails, while providing a cost-effective and reliable backupcapability for aPTC-started crossing system.