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 road crossing control unit (18) that may be selectively set to a primary or a secondary mode of operation is provided. In the primary mode of operation, the railway road crossing control unit is responsive to a primary activation signal (21) received from a primary activation-signal source (22), such as a positive train control (PTC) system. In the event the primary activation signal from the primary activation-signal source is not available, railway road crossing control unit (18) is set to the secondary mode of operation, where the railway road crossing control unit is responsive to one or more signals (25) received from a secondary activation-signal source (26) including a railway-vehicle sensing system (28) electrically-decoupled from a railroad track (12). Disclosed embodiments maintain operational robustness in the presence of changing weather and avoid variable electrical ballast conditions that otherwise could develop across the rails, while providing a cost-effective and reliable backup capability for a PTC-started crossing system.