SIGNALS AT HIGHWAY CROSSINGS FOR HIGH SPEED TRAINS

摘要

1285215 Level crossing control GENERAL SIGNAL CORP 14 Oct 1969 [18 Oct 1968] 50453/69 Heading B7N In a level crossing control system in which ordinary trains bring the highway crossing signals into operation by occupying a track circuit in advance of the crossing, the crossing signals are operated by very fast trains when an inductive device, provided only on such trains, co-operates with a similar device disposed on the track in advance of the track circuit. When an ordinary train enters the A.C. track circuit formed by transmitter 11 connected across rails 7 at point 9 and receiver 15 connected across the rails at point 10, track relay TR1 is released and via interlock apparatus 16 operates the highway signalling apparatus 17. The interlock apparatus ensures that the highway crossing signal is released when the train passes point 10 even though the track circuit controlling the crossing for movement in the opposite direction is occupied. A very fast train approaching the crossing actuates the inductive detector including coil R1 and momentarily releases relay D1 whereby the hold circuit of relay Q1 is broken and the track circuit supply is opened at front contact 12. Track relay TR1 is thus released to actuate the crossing signal. When the train reaches point 19 track relay TR2 is released, re-energizing relay Q1 which again locks over its front contact 22. This however does not affect the crossing signal because the train is now in the track circuit incorporating relay TR1 which remains released until the train passes point 10 on the track. In a further arrangement using radio transmission the inductive device on the track actuates a transmitter on the train and the received signal at the crossing again opens the track circuit to actuate the crossing signal. In addition the inductive device actuates apparatus defining two timing periods, at the end of the first of which the train brakes are applied unless a signal emitted by a transmitter which is controlled by apparatus responsive to a stalled vehicle at the crossing, is received on the train. The train transmitter is shut down at the end of the second period by which time the train has entered the approach track circuit.