GB1171991A - Highway Crossing Signal Control System - Google Patents

Abstract

1,171,991. Level crossing control. GENERAL SIGNAL CORP. 25 Jan., 1967 [1 Feb., 1966], No. 3675/67. Heading B7N. In a level crossing control arrangement, each crossing e.g. A is provided with a transmitter 10 which supplies a modulated A.C. current of a predetermined frequency F1 to the electrically continuous track rails 2, a pair of selective track receivers 11, 13 at the outer ends of the approach track sections for the crossing and a pair of line receivers 12, 14 which receive the modulated A.C. signals from the track receivers 11, 13 via line wires 4, 6 and control the road crossing signals SA via interlocking equipment 15. Where a second crossing B is relatively close to the crossing A, the apparatus for B operates at a different frequency F2 but shares the line wires 4, 6. Island apparatus i.e. short track circuits operating at high frequency are used at the crossings to terminate the road signals after passage of a train.