GB1076926A - Improvements in road traffic signalling systems - Google Patents

Abstract

1,076,926. Road traffic signals. MINISTER OF TRANSPORT and AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. Aug. 20, 1965 [Aug. 20, 1964], No. 34102/64. Heading G4Q. A vehicle presence detector (3) in the approach to a road junction maintains right of way on a road already possessing right of way so long as a vehicle is moving within the range of the detector. A second vehicle presence detector (5) may cover the actual junction and extend the inter-green period (which may include an all-red period) until the junction is clear. Alternatively the detectors in the approach roads may extend half-way across the junction (Fig. 5, not shown). The presence detectors may be inductive loops which cease to give an output shortly after a vehicle comes to rest within them, and may each cover a single lane or a plurality of lanes. A presence detector may be preceded by a passage detector, operation of which registers a demand if the road does not possess right of way or grants a fixed extension sufficient to allow the vehicle to travel to the presence detector if the road already has right of way. The passage detector may comprise a pair of road pads (1, 2) adapted to discriminate against actuation by a vehicle travelling in the wrong direction.