Patent GB-444969-A (GB)
Title: Improvements in road traffic control systems
IPC: G08G1/005
Filed: 1934-10-15
Abstract: 444,969. Road signals for controlling traffic. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., Caxton House, Tothill Street, Westminster, TYACK, F. G., 21, King William Street, Greenwich, and HERWALD, N., 59, Exeter Road, Cricklewood, both in London. Oct. 15, 1934, No. 29464. [Class 118 (ii)] The operation of a pedestrian button, provided on a vehicle actuated signalling system controlling traffic at an intersection, gives a "stop" signal to all approaches for a predetermined time, the right of way then returning to the road from which it was taken unless a demand is received from another road in which case it is first given to said other road. The pedestrian demand takes precedence over a vehicle demand if made after the vehicle demand but before the transfer of right of way has begun. The system is controlled entirely by relays. Pedestrian lamps indicating "Don't Cross" and "Cross Now" are provided. Specification 408,706 is referred to. Normal vehicle operation. When the right of way is with road A, relays ALC and BR are actuated. If now a call is received from road B, relay DE is actuated to set in operation the maximum green timer and the speed timer, the time of which can be extended by the repeated operation of relay RW by vehicles on road A. Relay DDE is operated. When relay ST of the speed timer is actuated, relay STA pulls up followed by relays RC and DCO. Relays DE and DDE fall away and relays RA, AM, CO and MG energize. The operation of RC transfers the relays RW and DE to road pads B and A respectively and the Maximum Green Timer from the Road A to the Road B regulator. The amber signal replaces the green signal on road A and the amber timer is set in operation. When the relay ST falls away, relay STS de-energizes and relays LC, BLC and BM operate to give the amber signal to road B and change the speed timer over to the road B setting. When the amber period has been measured off, relays AT, ATA and DAT energize, relays RA, AM and BM release and relay GC pulls up to give right of way to the B road. When relay AT falls away, relays ATA, DAT and CO release and tne amber timer is connected to the B minimum green regulator to measure off the minimum green period of the B road. When relays AT, ATA and DAT energize at the end of this period, relay MG releases and the apparatus is in condition for a vehicle in road A to initiate return of the right of way. Pedestrian demand. When the pedestrian button PB is depressed relay DP is energized and operates relay DE. The speed and maximum green timers are brought into operation and relays ST and STA operate as before. Relays DE and ALC release and relays RA, TA, CO, MG and AM pull up. The amber signal is thus given to road A whilst the red remains on road B. Relay DRT pulls up and the amber timer measures off an amber period. Relay DRW is connected to rod-pad A to record the passage of vehicles over the treadle. At the end of the amber period relays AT, ATA and DAT operate. Relays RA, CO and AM de-energize and relays RR, AR and DPL pull up. The red signal is given to road A, the pedestrian "Cross Now" signal is lit and the " Don't Cross " signal extinguished. The amber timer is connected to the overlapping red regulator and at the end of the "all red" period relays AT, ATA and DAT pull up. Relays OTA, DP, DPL and MG fall away and relays ALC and AM pull up. The amber lamp is lit on road A, the "Cross Now" lamp is extinguished and the "Don't Cross" lamp lit. Relays AT, ATA and DAT release and RA operates followed by CO and MG. Relays RR and DRT release. The amber timer now measures off an amber period at the end of which relays AT, ATA and DAT again operate. Relays RA, AM and AR release so that right of way is again given to road A. Pedestrian demand following vehicle demand. If a pedestrian demand follows a vehicle demand before the speed timer is operated, the pedestrian demand is satisfied first. Under these conditions the treadle has operated relay DE and DDE has been energized. Operation of the pedestrian button energizes relay DRP and relays DP and DRE are then operated. When the speed timer operates relays STA, OTA, RA, AM, DRT and CO pull up and the apparatus operates as described above for a pedestrian demand. At the end of the overlapping red period, however, the right of way is transferred to road B instead of returning to road A. The right of way is also transferred to road B if the call from road B is made after the pedestrian demand has been made.