A description of fixed-time and vehicle-actuated traffic signals, including details of the various facilities available with president British vehicle actuated equipment, is given in this paper. Some information on pedestrian signals is also included. Methods of coordinating signals aft two or more intersections are discussed. Information is given on the various stages in the design of a signal scheme, e.g. warrants for signals; layout and siting of signals, islands and detectors; use of carriageway markings; widths of approaches and the use of special right-turning lanes and left filters; phasing and clearance periods. The results of research into the capacity of intersections controlled by traffic signals are described and it is shown how capacity is affected by the width of the carriageway, the gradient, the type of site, the presence of right turning vehicles, heavy commercial vehicles and parked vehicles. The results of research using an electronic computer to simulate traffic at traffic signals, previously published in Road Research Technical Paper No. 39, are repeated in this paper for completeness.
Abstract