GB1274244A - An area road traffic control system - Google Patents

Abstract

1,274,244. Road signals for controlling traffic. OMRON TATEISI ELECTRONICS CO. 19 May, 1969 [30 May, 1968], No. 25463/69. Heading G4Q. A traffic control system for a road netwrok consisting of six intersecting main highways 11 ... 16 and eight local roads 21 ... 28 comprises dividing the network into a number of unit zones each centred about the intersection of two main highways. These intersections are designated I 1 ...I 9 and are provided respectively with zone control devices 31...39. Each device 31...39 controls traffic signals (not shown) within its corresponding zone. Vehicle detectors 41, 41<SP>1</SP> ... 52, 52<SP>1</SP> are situated between adjacent pairs of the intersections I 1 ...I 9 . The dash lines in Fig. 1 show the extent of the unit zone centred on intersection I 5 and Fig. 2 shows in block diagram form the circuit connections for that zone, the other unit zones being similar. As shown, the vehicle detectors 44, 44<SP>1</SP>, 46, 46<SP>1</SP>, 47, 47<SP>1</SP>, 49, 49<SP>1</SP> on the periphery of the unit zone supply signals to the zone control device 35 and to a central control station 61. The zone control devices of the other unit zones similarly receive signals from the corresponding vehicle detectors and the station 61 receives signals from all the vehicle detectors. Consequent upon the traffic retardation as computed by the station 61 the traffic is controlled in one of three ways as shown in Fig. 3. The station 61 determines whether signals from any one of the four pairs of detectors of any zone are above a certain level and indicate a heavy traffic volume. Such zones having a heavy volume are controlled as a group directly by the station 61 to an optimum predetermined traffic control pattern. If the traffic volume is below this level the zone is controlled by its control device and the station 61 disconnects itself from that zone. However, if the traffic volume is relatively heavy but there is a large variation of traffic volume with respect to time, the zone is disconnected from the station 61 and is controlled by its control device which additionally applies retardation control.