GB744183A - Improvements in or relating to systems for regulating vehicular traffic in main thoroughfares - Google Patents

Abstract

744,183. Road signals for controlling traffic. SIEMENS & HALSKE AGT.-GES. May 13, 1953 [May 19, 1952], No. 13437/53. Class 118(2) In a progressive system in which the timing of main light signals S located at the intersections of side roads with a main road are correlated to facilitate the uninterrupted passage of vehicles along the main road at a constant, predetermined speed, the smooth flow of traffic is further ensured by locating a preliminary light signal PS a distance, e.g. 50 metres, in advance of each main signal equal to that required by a normal vehicle to accelerate from rest to the predetermined speed. The main and preliminary signals both display the same conventional sequence of coloured lights, in red, red with amber, green, amber...but the timing of each preliminary signal is advanced relative to that of its associated main signal by the time taken to travel between them. The Figure shows such an arrangement for a main road Str with a central tram track tr and traffic travelling on the right-hand side of the road. A pedestrian crossing F and an island i for tram passengers are located between signals S and PS. A further signal FS is located at the crossing F to protect it from traffic filtering into the main road from the side road, the timing of signal FS being so related to that of the main signal S that the filtering traffic joins the main traffic stream in the correct phase. Additional intermediate signals JS (Fig. 6. not shown) which display only the green "go" condition may be located between two sets of main signals, the timing of each intermediate signal being displaced relative to that of the main signals by an amount proportional to its distance from them. Preferably, the intermediate signals are so numerous that a strip of green light appears to travel along the main road at the predetermined speed, the length of the strip being equal to the product of the predetermined speed and the "go" time of the signals. The intermediate signals JS may comprise luminous studs in the centre of the road or they may be located in the kerbstones at the edges of the road and at the edges of the central tram tracks alternate ones of such an array of signals may be directed in opposite direction along the main road (Fig. 1, not shown). Advance signals AS, Fig 6 (not shown), similar to the intermediate signals JS may be located before the first crossing in order to filter traffic approaching the controlled zone into groups travelling at the requisite speed. Traffic now diagrams illustrating the effect of the invention are given in Figs. 1, 2, 3 and 6 (not shown).