Patent GB-1105799-A (GB)
Title: A local traffic signal controller
IPC: G08G1/081
Filed: 1966-09-05
Abstract: 1,105,799. Road traffic control. TATEISI ELECTRONICS CO. 5 Sept., 1966 [9 Sept., 1965], No. 39617/66. Heading G4Q. A local controller 2 for controlling traffic flow at an intersection is arranged to provide (a) fixed time control using unit 7, (b) traffic actuated control in which the operation of unit 7 is modified by signals from a traffic actuated unit 6 and (c) co-ordinated traffic actuated control in which the operation of unit 7 is modified by signals from unit 6 and from co-ordinating unit 4 coupled to a master controller 1. Fixed time control: Decimal counters 4Cl, 4C2 are driven by 1 sec. pulses from generater 4S1 and their outputs are connected to pin boards 4B1-4B6 which can be set to provide output signals on associated lines M10-40 and L10-20 at predetermined counts in the counting cycle. Assume a counting cycle of 95 sees., pinboards 4B1-4B4 are set to 50, 55, 90 and 95 counts respectively and at these times in each cycle signals appear respectively on lines M10-40 and hence via OR circuit 4R2 on output line 40. This line is connected to a 4 stage counter, Fig. 5 (not shown), with its outputs connected to six pin boards with output lines controlling the green, amber and red lights on the main road and the three similar lights on the crossing road. The cycle starts with the 95th pulse on line M40 which via inhibit circuit 4H1 returns the counters 4C1 and 4C2 to zero and also energizes the first stage of the 4 stage counter to supply via the associated pin boards an energizing circuit for the green light on the main road and the red on the crossing road. After 50 sees. the counter receives a second pulse and switches the main road to amber, after a further 5 sees. a third pulse switches the main road to red and the crossing road to green, after a further 35 sees. a fourth pulse switches the crossing road to amber and a further 5 secs. later the 95th pulse appears to repeat the sequence. Traffic actuated control: In this arrangement counting is suspended during the two main timing periods, i.e. main road green, crossing red and crossing green and main road red and the period durations are determined by the presence of traffic on the road having right of way, being a maximum green value when traffic is present and a minimum green value in its absence. Thus the cycle duration is variable. Co-ordinated Traffic Actuated Control: For this type of control the pin boards 4B1-4B6 may be set to 10, 15, 25, 30, 8 and 23 counts respectively and when a signal appears on line M40 the cycle which is of 160 sees. duration commences as before described by supplying the first pulse to the 4-stage counter. At the end of 8 sees. the signal on line L10 switches a memory circuit 4F1 which supplies an output to block the counters 4C1, 4C2. After a maximum period of 80 sees. when the master controller emits a signal to terminate the main road green period or after a minimum shorter period if no traffic is detected on the main road a signal is received which switches the memory circuit back to its initial state and counting recommences for 2 sees. when a signal appears on line M10 and supplies the 4 stage counter with its 2nd pulse. After a further 5 seconds the signal on line M20 supplies the 4 stage counter with its 3rd pulse. After a further 8 seconds a signal appears on line L20 which again switches the memory circuit to its counter cut off condition. After a period which maintains the overall cycle time constant the master controller supplies a pulse which returns the memory circuit to its initial state and counting recommences. After 2 sees. a signal appears on M30 which provides the 4th pulse to the 4-stage counter and after a further 5 sees. a signal appears on line M40 to initiate the next cycle.