Patent GB-501191-A (GB)
Title: Improvements in road traffic control systems
IPC: G08G1/082
Filed: 1937-05-21
Abstract: 501,191. Road signals for controlling traffic. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., DOWNES, F. A., and HERWALD, N. May 21, 1937, No. 14210. [Class 118(ii)] In a progressive system, vehicle-actuated slave controllers are arranged at each intersection and rotary switches are adapted to be driven in synchronism and associated with the respective controllers to give progressive control. The slave controllers may be similar to those described in Specification 408,706, the essential addition being a synchronous motor M driving switches W1, W2 at each controller. For a period (the " prevent " period), which is not less than the minimum green period for the cross-road, demands by the cross traffic are ineffective, but are stored, if the right-of-way is on the main road. If the right-of-way is on the cross-road, it may be extended up to the end of the prevent period, when it passes to the main road upon demand. During the next or "privilege" period, the right-of-way remains on the main road. For the remainder of the cycle the controller either acts independently or gives similar periods to the cross traffic if it is also progressively controlled. Specification 450,602 also is referred to. Slave controller. Upon wipers W1, W2 reaching contacts 1, relays PE, TA are energized. If the right-of-way is on the main road A, demands from the cross traffic are stored by operating relay DE, the Speed Timer being ineffective due to the operation of TA and PM. The Maximum Green Timer is prevented from operation due to the operation of PG. If right-of-way is on the cross-road, it may be extended by operation of relay RW up to the end of the prevent period. Upon relay PG operating, the change of right-of-way is forced by the Maximum Green Timer if a demand has been made by main road traffic. The right-of-way remains on the main road throughout the privilege period since the Speed Timer circuit is broken due to operation of relay PM. During the period when the wipers are on contacts 16... 25, the controller works independently and this period will be extended to contact 50 if only the main road A is progressively controlled, but if road B is similarly controlled, prevent and privilege periods are given when wipers are on contacts 26 ... 29 and 30 ... 35 respectively. Master controller. The rate of progression is varied by changing the frequency of the A.C. supplied to the slave controllers, the generator A being run from a variable speed motor VSM, or an oscillator or vibrator may be used; the control of which may be by a traffic integrator. In order to synchronize the running of the motors M, a similar motor S is provided which closes a contact M1,. once per revolution. Contact Z1 normally closed is opened when'the wipers reach contact 1, Z2 being opened when Z1 is closed. Upon commencing operation, Z1 will, in general, be closed so that relay MS operates and motor M runs until Contact Z1 opens. Upon contact M1 closing, relay PS will operate and motor M will restart and remain running as contact ps1 will be closed when contact Z 1 is open. Alarm circuit. If the motor M does not operate, relay PB pulls up after an interval, causing relay PN to lock up and lamp AL to light. This circuit is reset upon the motor commencing to run in synchronism or may be reset by the key. Relay PN also prepares the Speed Timer circuit so that the controller may operate as an isolated controller. Manual Controls. Upon the Hand Control switch being reversed, the controller may be operated manually by the depression of the Hand Button Control, when relay MTA will operate if MG is released, to change the rightof-way. An all-red facility is provided when the four all-red keys are operated.