Patent GB-427832-A (GB)
Title: Improvements in or relating to vehicle actuated road traffic control systems
IPC: G08G1/08
Filed: 1934-01-02
Abstract: 427,832. Road signals for controlling traffic. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., Tothill Street, and TYACK, F. G., King William Street, Greenwich, both in London. Jan. 2, 1934, No. 157. [Class 118 (ii)] In a vehicle-actuated system for three or more intersecting roads in which right of way is given to only one road at a time, right of way is transferred to the first road from which a demand is received. Minimum and maximum timing is provided and an increased amber period is given if right of way is forcibly taken from a road. The transfer is controlled by a single marker such as a relay chain or selector switch, if three roads only are concerned, and an additional marker is provided for each additional road at the intersection to ensure transfer in correct sequence. Right of way remains with a road until a demand for transfer is received. Although the same timers are used for all roads, the various predetermined time periods are adjustable individually for each road. The extension of the minimum period is inversely proportional to the speed of a passing vehicle. As described, the invention is applied to a system for three intersecting roads called hereafter A, B and C respectively. Assuming the right of way is with road A and road B calls. Relays AL, BR and CR are energized so that lamps AG, BR and CR are lit. When the demand is received on road B, pad B is depressed and relay BD operates and locks. Relay DE pulls up and the pulse circuit including relay PT, tube P and condenser QND is effective so that relay FB is energized and marker relay HB pulls up to open the pulse circuit. Had the demand been from road C, HB would not be energized when FB operated and relay FC would have pulled up allowing relay HC to operate and lock. The maximum green timer is set in operation over contact de2 and the speed timer is connected up over contact hb2 if both relays MG and ATA are back, that is if both the amber and minimum green times have elapsed. Any further demands on road A operate relay RW and whilst the pad is depressed and relay RW is operated, the condenser QNB is connected in a charging circuit. When relay RW is back the condenser QNB is discharging and when this condenser is sufficiently discharged relay ST pulls up and relay STA energizes followed by relay RA. Relay AL falls away and relay AA operates to extinguish the green light and light the amber lamp on road A. Relays ST and STA release and SB pulls up and locks. The road pad A is disconnected from relay RW and connected to relay AD so that demands for transfer can be registered and the road pad B is disconnected from BD and connected to relay RW. Contacts sb5 and sb6 connect the speed and maximum green timers to the road B connections. Relays BL, BA, BG, CO and MG pull up and the amber signal on road B is lit. Condenser QNC is charged and condenser QNB is partly discharged. The speed timer is disconnected at mg4 to prevent operation during the amber and minimum green periods. At the end of the amber period relay AT operates followed by ATA. Relays AA, BA and BR release to extinguish the amber lights on roads A and B and the red lamp on road B, and relay RA pulls up to light the red lamp on road A. Relay BG is already locked up so that the green lamp on road B is lit. Relay CO releases to allow the amber timer to measure off the minimum green period which is determined by the preset adjustment connected over bl3. At the end of the minimum green period relays AT and ATA again operate and relay MG releases to complete the transfer of right of way. Had the right of way been transferred to the C road, the minimum and maximum green periods and the speed timer would have been controlled over cl3, sc5 and sc6 respectively. If the right of way is forcibly taken from a road by the operation of the maximum timer, relays MT and MTA are energized. The speed timer is operated over mta5 to initiate the transfer, and the relay AD, BD or CD corresponding to the road having right of way is operated to register a demand and ensure re-transfer. The short circuit across resistance ZO is removed to increase the amber period. The timers are similar to those described in Specification 408,706.