Highway crossing control system for railroads utilizing a communications link between the train locomotive and the crossing protection equipment

摘要

Highway crossing protection equipment which operates warning lights or crossing gates is controlled from the train locomotive which enters into an interchange of messages via a radio link with the controller at the crossing. Communications between the train and the crossing controller is initiated when the locomotive passes a trackside beacon transponder located beyond a safe braking distance from the crossing. If communication is not established before the train reaches the safe braking distance, the brakes are applied and the train is not permitted to travel into the crossing. Optionally the driver of the train may be required to actuate a pre-acknowledge switch before reaching the location of the beacon so that the brakes will be applied if either the pre-acknowledge switch is not actuated within the time expected for the train to reach the beacon location or no signals are received from the beacon, thereby verifying beacon operation. At the crossing, after communication is established, a timer is set so as to prevent actuation of the protection equipment (gates down or warning lights flashing) for a minimum time depending upon information in the message received from the train as to its speed and distance from the crossing and track conditions in the vicinity of the crossing (e.g., grade). The crossing controller transmits a message addressed to the train acknowledging the receipt of the train signal. The message from the crossing controller causes the train to send a subsequent message within the minimum time which is used to update the timer (the minimum time) for the crossing to be actuated to its safe condition. The interchange of messages can be repeated a plurality of times; each time the minimum time being updated so that traffic flow across the crossing is handled efficiently with minimum interference. All communications are handled through vital communications logic which activates the protection equipment to its safe condition or sets alarms or brakes in the train in the event of errors or failures in the messages being handled in the crossing controller or in the train equipment, respectively. Further safety and vital checks may be provided through the use of approach track circuits to operate the crossing protection equipment if a communication link between the train and the crossing controller is not established. Wayside signals may also be used to warn the train driver to stop the train unless the communication link has been established. The crossing protection equipment is responsive to successive occupancy and unoccupancy of the crossing (as may be detected by local crossing track circuits) for operating the protection equipment to a state to permit highway traffic flow across the crossing. IMAGE