GB974461A - Traffic control system - Google Patents

Abstract

974,461. Road signals for controlling traffic. THOMPSON RAMO WOOLDRIDGE Inc. May 17, 1963 [May 28, 1962], No. 19773/63. Heading G4Q. A traffic control system comprising a plurality of junction traffic light sets, each comprising a local controller, is provided with a computer which holds the operation of a local controller at a point in its cycle until a release command is given; means for storing a programme in the computer for computing an operating plan and determining release times in dependence on existing traffic conditions; a time of day clock; and means for transmitting a release command when a predetermined release time and time of day coincide. Each local controller comprises a contact 32 which rotates over fixed contacts 38, 40, 42, 44 to sequentially light the red, green and amber lights of the two phases. In order to prolong a green phase one or other of solenoids 50 is energized, moving its plunger to prevent contact 32 from rotating, the energization being effected by tones transmitted from the computer. When the time of day occurs for a release command to be given, the appropriate tone from the computer is interrupted releasing the plunger of one of the solenoids and allowing the contact 32 to rotate to the next phase in the cycle. Failure of the command tones allows contact 32 to continue rotating giving independent control at each junction.