Patent GB-488024-A (GB)
Title: Improvements in or relating to road traffic control systems
IPC: G08G1/082
Filed: 1936-10-29
Abstract: 488,024. Road signals for controlling traffic. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., DOWNES, F. A., and RIDDLE, H. J. N. Oct. 29, 1936, No. 29434. [Class 118 (ii)] In a traffic control system, the controller controlling the signals at an intersection includes a rotary switch arranged to rotate continuously and thereby to complete a plurality of circuits in succession, and a ratio switch arranged to associate any signal with any one of the circuits independently of the others. Independently controlled intersection. The local timer, operating when contact al2 is closed, comprises relay IR, neon tube N, resistances R1, RA1 and condenser Q1, the flashing of tube N operating IR, causing the uniselector switch magnet UW to be energized to step wiper WA one contact on the rotary switch provided with fifty contacts connected to the fifty rows of contacts on the ratio switch. Twelve rods carry contacts, slidable over these rows of contacts, the position of the rod contacts determining the length of time a signal is operated. Considering the control of road A with the ratio switch as shown, a wiper WA passes over contact 42, relay AG is energized and locks, releasing relays AA and AR, and energizing the green lamp on road A. Upon the wiper WA reaching contact 1, AA is energized and locks, releasing AG and changing the signals to amber. At contact 3, AR is energized and locks, releasing AA and changing the signals to red while at contact 40 AA is energized and locks, giving the amber-with-red signal, the cycle being completed at contact 42. Slave controller. The master controller is provided with a timer as above, and transmits pulses to the controller, now acting as a slave controller, the pulses also being used to step a switch causing a relay to operate once in each cycle so that a longer pulse is transmitted for synchronizing. Upon the receipt of a pulse from the master-timer, relay FP operates, causing Q1 to discharge sufficiently into condenser Q3 for tube N to flash and operate IR. Wiper WA is thus stepped on at a rate determined by the frequency of the pulses. Upon wiper WA reaching the contact connected to the rod X, relay X operates, connecting Q1 and Q2 in parallel so that FP must be energized for a longer period. The normal pulse is insufficiently long so that the wiper WA remains in this position until the long synchronizing pulse is sent, when condenser Q1 is sufficiently discharged for tube N to flash causing wiper WA to advance. Since the contact controlling relay X is adjustable, although the position in the master timer cycle when the synchronizing pulse is sent is fixed, the various slave controllers may be adjusted to have phase relationship. Condenser Q4, charged through resistance R5 is partly discharged at every pulse by condenser Q5 and resistance R4, thus preventing the neon tube NAL from striking. Upon failure of the master timer, tube NAL strikes and relay AL operates, locking up and completing the local timing circuit over al2, so that the controller operates independently. A remote control may operate relay RC breaking the supply to the controller and causing amber globes to light. A hand key switch HKS is provided to allow manual operation, wipers WA1, WA2 passing over contact banks to energize the corresponding relays. The green relays are mechanically interlocked to permit the operation of only one at a time. Pedestrian crossing. Assume the system is working as an independent controller and the pedestrian traffic to have road B. Contact al2 is arranged to be operated by X, the position of the contact, as shown, corresponding to the energized condition of X, condenser Q2 being dispensed with. Contact on rod X is adjusted to a position just before the right of way passes to the B road. The local timing circuit causes wiper WA to step round to the contact on rod X whereupon relay X pulls up and al2 opens the timing circuit, Q1 being charged over resistance R3. If the pedestrian button is pressed, FP operates, causing condenser Q1 to discharge and IR to operate so that wiper WA passes on to give the right of way to road B. In the absence of a call, the right of way remains with road A. U.S.A. Specification 1,931,851 is referred to.