Patent GB-356102-A (GB)
Title: Improvements in road traffic control systems
IPC: G08G1/08
Filed: 1930-04-30
Abstract: 356,102. Road signals for controlling traffic. GILL, H. A., 51, Chancery Lane, London.-(Automatic Signal Corporation ; 205, Church Street, New Haven, Connecticut, U.S.A.) April 30, 1930, No. 13308. [Class 118 (ii).] An automatic signalling system for controlling vehicular traffic at road intersections is operated (a) by the traffic through timing mechanisms, (b) by the timing mechanisms only, or (c) manually, in such a way that: (1) Right of way is given successively to several traffic lanes in an order which may be predetermined but so that the length of time one lane retains the right of way is dependent upon either the approach of vehicles in that lane or upon the approach of vehicles in one or more other lanes, or upon both; (2) A traffic lane which does not require right of way cannot hold it to the disadvantage of one which does ; (3) A vehicle whose progress is prevented by a continuous stream of opposing traffic may not be required to wait more than a predetermined period of time at the end of which the vehicle is given right of way for a time sufficient for it and following vehicles to cross the intersection; (4) A vehicle which has passed an actuating means is protected against opposing traffic for a period of time sufficient to permit it to pass the intersection ; (5) A vehicle approaching an intersection is given immediate right of way if there is no opposing traffic in or immediately approaching the intersection ; (6) When a vehicle is not given immediate right of way or has right of way taken from it before it has had sufficient time to cross the intersection, the system is left in such a condition that right of way will return to the delayed vehicle as soon as traffic conditions permit; (7) Periodically right of way shifts to another lane even though there is no traffic on that lane, to allow pedestrians to cross the intersection; (8) When the signalling means and timing mechanism are disconnected from the traffic-actuated means, right of way is given successively to the various traffic lanes according to a predetermined sequence and to each lane for a predetermined time interval; (9) When the traffic actuated means is disconnected the signal means may be operated manually ; (10) The timing of the warning signal, interposed between right of way and stop signals, may be varied according to the existing traffic conditions ; (11) A vehicle is protected against opposing traffic for a time commensurate with its speed; (12) If one or more vehicles after passing the actuating means, do not receive right of way immediately, they are protected against opposing traffic when they receive right of way for a period of time proportional to the number of cars to enable the latter to start plus a period to enable them to cross the intersection. The vehicle-actuated controls 1 .. 4, Fig. 1, at an intersection each comprise a ramp 7 pivoted at 8, Fig. 2, which, when depressed by a vehicle closes contacts 10, 11, the ramp being returned to its normal raised position by a spring 9. The signal means 5, Fig. 1, comprises a yellow lamp Y, Fig. 5, visible to both A and B streets and a green G and red R lamp for each street, the green and red lamps of opposing streets being connected in series. Timing mechanism. When wires (e e) 14, 15, Fig. 3, are energized, a relay 17 operates, and a condenser 24 is charged up over a variable resistance 19, contact 20 and armature 21. When the voltage across the condenser 24 reaches the critical voltage of a glow tube 26 the latter becomes con, ducting and a relay 27 in series therewith operates and locks up over contacts 29, 30. When the supply is disconnected from wires 14, 15, relay 17 de-energizes and condenser 24 discharges through a resistance 33. The time lag of the device, that is the interval between the application of power to wires 14, 15, and the operation of relay 27, may be varied by means of the resistance 19. Operation. Fig. 5 shows the right of way on A street, a relay 34 being energized to light the A street green and B street red lights over wires 35, 36, 39. Timing mechanisms 40, 41, similar to that shown in Fig. 3, and a relay 42 are also energized. The A and B street actuating devices are connected respectively across wires 127, 128 and 43, 44, and, should a single vehicle now come, along B street, there being no traffic on A street, relay 45 is momentarily actuated by the ramp in B street, causing a relay 46 to operate and lock up over contact 92. Relay 46, at contact 53, breaks the circuit of the timing mechanism 40, which in releasing breaks, at contact 63, the circuit of relay 34, the armature 38 of which breaks the circuit to the A street green and B street red lights at contact 37, and energizes, at contact 74, the yellow light. The armature 82 of relay 34, having broken the circuit of relay 42, makes the energizing circuit of timing mechanism 80. After three seconds, say (the time lag of timing mechanism 80), armature 101 is attracted, breaking the operating circuit of timing mechanism 41, and making the circuit of a relay 111, which at armature 78 extinguishes the yellow light Y and illuminates the A street red and B street green lamps over wire 120 to allow the vehicle to pass. When timing-mechanism 40 has de-energized, a timing-mechanism 121 energizes over contact 63. Should a vehicle approach on A street as soon as the right of way has thus been transferred to B street, the actuated ramp will momentarily energize a relay 129 causing relay 42 to operate and lock up over armature 96, contact 132 and armature 133. (If this vehicle had approached on A street while the amber signal was showing, prior to right of way passing to B street, relay 129 would break the circuit of timing mechanism 41, but in the present case this circuit has already been broken at contact 101 by the operation of mechanism 80.) After ten seconds (the time lag of mechanisms 121), the energizing circuit of timing-mechanism 80 is broken at armature 90, causing relay 111 to de-energize, change the signal indication to yellow, and at the same time reestablish the circuit of timing mechanism 40, which after three seconds, say (its time lag and the duration of Y signal), operates its armature 63 to break circuit of timing mechanism 121 and energize relay 34 for operating the lamps giving right of way to A street. Thus, if a vehicle approaches along a road which has just lost right of way to a single vehicle it cannot be given right of way for ten seconds, a time sufficient for the opposing car to cross the intersection, timing-mechanisms 41, 121 performing these functions for A and B streets respectively. Should a number of vehicles approach on B street within ten seconds of each other, B street having right of way, relay 45 will be momentarily energized as each car passes, breaking the circuit of the timing-mechanism 121 an equal number of times. Each time this happens the condenser 24, Fig. 3, of mechanism 121 discharges through resistance 33, so that the timing- mechanism 121 will not operate to allow right of way to be transferred to A street, assuming a vehicle thereon has actuated relay 42, until approximately ten seconds after the last vehicle has passed the intersection from B street. Timing mechanism 41 functions similarly for A street. If a vehicle is waiting on A street and there is continuous traffic on B street, say, the timing-mechanism 121 being continuously reset will not operate. A further timing-mechanism 137 is operated by this approaching vehicle on A street (by a contact of relay 42) and after its timing period (say thirty seconds) deenergizes relay 80 at contact 86, when the right of way is transferred to A street as before, for ten seconds. Relay 46 remains energized, however, which is equivalent to the approach of a vehicle on B street so that right of way will be transferred back again to B street after the car on A street has used its allotted ten seconds. A timing- mechanism 139 functions similarly to prevent continuous traffic on A street for more than thirty seconds. Speed of vehicles crossing an intersection. With continuous traffic on, say, B street, the time the relay 45 is energized is in each case commensurate with the speed of the actuating vehicle so that the times of breaking of the circuit of timing-mechanism 121 are also each commensurate with the speed of the actuating vehicle. If the energizing circuit e e of Fig. 3 is broken for only a short period the condenser 24 will not completely discharge, and, when the energizing circuit is again made, a full ten seconds will not be required before the condenser reaches the critical voltage and so actuates the timing-mechanism. Accordingly, although the first vehicle crossing the intersection from B street is given ten seconds, following vehicles are given a smaller time period, commensurate with their speed. By closing switches 141, 142 relays 42, 46 are continuously energized and the right of way is granted alternately to each street for any period between ten and thirty seconds according to whether there is no traffic or continuous traffic. Operation by timing-mechanism only. Switches 143, 144 are thrown to their " down positions, disconnecting the road controls and shorting switches 141, 142 so that relays 42, 46 are continuously energized, timing-mechanisms 41, 121 are continuously interrupted, and right of way is given alternately to each street for thirty seconds by timing-mechanisms 137, 139. Manual operation. Opening of switches 145, 146 will de-energize relays 34, 111 to show the yellow light, closing of switches 145, 146 selectively to their down positions energizing the corresponding relays 34, 111 to give right of way to A street and B street respectively. Emergency control. By closing a switch 147, a relay 148 is energized breaking the circuits of both relays 34, 111, and changing any signal given to yellow. The emergency control may be put into operatio