Patent GB-500288-A (GB)
Title: Improvements in road traffic control systems
IPC: G08G1/08
Filed: 1937-07-05
Abstract: 500,288. Road signals for controlling traffic. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., NOBLE, J. D., and TYACK, F. G. July 5, 1937, No. 18679. [Class 118 (ii)] In a vehicle-actuated system wherein the extensions by vehicles of the right of way period are such as to prevent straggling traffic retaining the right of way in the face of a demand, a device is arranged to respond to actuations of the road pad in the road having the right of way so as to ensure that if the right of way is transferred to another route before the end of the maximum period and within a given period of the last actuation of the road pad, then the time taken to effect the transfer is increased to allow the last vehicle to cross the intersection before the right of way is acquired by the other route. The system is described as applied to a controller of the type described in Specification 408,706, an overlapping red timer being provided, operated in a manner similar to the speed timer, the extensions given on each operation of the road pad being longer. Upon operation of the speed timer a short testing period is provided, during which the overlapping red timer is given an opportunity to operate. If it does not operate, an all-red period is introduced into the transfer of right of way, whereas if it operates, no all-red period is introduced and transfer takes place in the normal manner. Detailed operation. Upon a vehicle passing over pad A relays RW, RWA operate, delaying the operation of the speed timer, and the discharge of condenser QND in the circuit of the overlapping red timer comprising relay OR, neon tube SR and discharge resistance ZB. Upon a demand being made by a vehicle on road B, the speed timer will eventually operate and it is assumed that operation occurs before the maximum timer operates. Relays RC, LC, CO (not shown), and RA, MG operate. Relays RAA, ALC release, while relay ORT operates and locks up during the release period of ALC causing relay TAR to release. The amber contactor relay AM operates and looks so that an amber period for road A is commenced. If there are no unexpired extensions being measured off by the condenser QND and discharge resistance,ZB then neon SR will flash during the testing period provided by the slow release of TAR, and relays OR, ORA operate, ORT releasing, causing B.LC, TAR to operate and thus operating the B road amber contactor relay BM. In this case transfer of right of way proceeds in the normal manner. If however a demand is made by a vehicle on road B when either the minimum green period has not expired or there is an unexpired extension of the overlapping red timer so that neon tube SR will not strike then the overlapping red period is introduced. When the speed timer operates following the end of the minimum green period, MG, MGA release and the tube is not able to strike before TAR is released, so that OTA now operates and locks, causing GC to release. An amber period is now measured off with the A road amber lamps only illuminated. At its termination RA releases causing RAA to operate, CO also releasing, and RR operating to hold BR operated maintaining the red period for road B. The overlapping red period is now timed using discharge resistance ZB, OR, ORA operating causing OTA, ORT to release and RA then operating. Upon relays OTA, ORT releasing, BLC pulls up to release RAA and lock up relay BM so that the amber signals are displayed on both roads and relays OR, ORA, RR release. When the amber period has been measured off RA, CO, RM release and RAA, GC operates so that right of way is now on road B.