Patent GB-506384-A (GB)
Title: Improvements in or relating to traffic control systems
IPC: G08G1/08
Filed: 1937-11-23
Abstract: 506,384. Road signals for controlling traffic. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd., and THOMPSON, G. W. Nov. 23,1937, No. 32264. [Class 118 (ii)] In a system arranged for the caution signal to traffic about to receive right of way to be displayed independently of the caution signal to traffic about to lose right of way, ,provision is made for varying the interval between the instants of commencement of the two signals, and the duration of the latter, in accordance with traffic conditions as tested at.the beginning of the latter signal. As described with reference to a normal intersection, the red-withamber signal RA, Fig. 4, is delayed by a short test period, and, in the event of the right of way being terminated due to operation of the maximum timer or if a vehicle operates the road pad during this test period, the amber-leaving signal AL is prolonged and the red-with-amber signal RA delayed, the transfer then taking place as shown in Fig. 5, so that the RA signal is always of the same duration. Provision is also made for a suppressible all-red period to be inserted between the giving of the two caution signals, this being particularly useful where a junction road runs into one of the roads near the intersection. As applied to a three-phase controller the test period may be utilized to determine to which phase the right of way shall pass and whether an all-red period shall be inserted. The invention is described as applied to a system of the type described in Specification 475, 118. Two-phase intersection. Upon the stopping switch D passing to position 3 the amberleaving signal is given over switch bank D2, and, if no extension of the amber-leaving period is required, lamp FB will flash at the end of the test period, relays DX and ALR operating and causing the switch to be quickstepped to position 5 where the red-withamber signal is given due to relay RA pulling up. Upon the expiration of the normal amber-leaving period timed over lead 10, lamp FA flashes and AR operates to step the switch, relay RCO operating to release ALR. If right of way is terminated due to the operation of the maximum timer, road relay EX (not shown) will be operated, the switch D remaining in position 3 for the extra period due to the charging of condenser QB only taking place over high resistance 21, the charging of condenser QA being delayed by the insertion of resistance 24 so that switch D remains in position 5 for the normal period. If an isolated vehicle operates relay EX during the test period, condenser QB is momentarily. shorted. and the amber-leaving signal prolonged as above. Three-phase controller; suppressible allred period. When the all-red period is required, relay RCO is operated in position 3, lamp FA flashing and AR operating to terminate the amber-leaving signal, whereupon the all-red period is timed over lead 11 before the switch is stepped to position 5 to time the red-withamber signal. When RCO is operated the all-red period is suppressed, but if a vehicle is registered during the test period, RCO, is operated and the all-red period reinserted. It may be arranged that in a two-phase controller relay RCO is initially operated but released in position 4, so that the two caution periods are given consecutively as described in Specification 419,751. In a further modification, high resistance 21 may be omitted and resistance 24 shorted, the alternative transfers then being as shown in Fig. 4 and in Fig. 5 with the red signal commencing at the end of the normal AL period. If it is desired to provide an all-red period then, when EX operates, it may cause RCO to operate in position 4.