Train type discrimination system for level crossings - uses pulse circuitry on fast trains to activate level crossing warning devices earlier than slow trains which use DC near crossing

摘要

To discriminate between different kinds of rail traffic, for example to distinguish fast trains from slow trains, thus allowing shorter delays to motorists at level crossings, a pulse generator is fitted to fast trains and the pulses detected by inductors between the rails. The pulse detectors are placed in a track zone further from a level crossing than a zone using a d.c. detection circuit. The warning devices at a level crossing are activated when either a suitably coded pulse signal is detected, or when the output of a d.c. generator connected to the rails is short circuited by a passing train. Thus a fast train carrying the pulse generator operates the level crossing devices earlier than a slow train which must reach the d.c. detection zone before the level crossing devices are activated. In the event of the pulse detector failing to operate, the d.c. detection zone provides back up operation for a fast train.