ABSTRACT
In urban networks, the distance between neighbouring intersections is frequently too small for platoons of traffic released by one intersection to disperse completely before arrival at the next intersection (about 1 km is required for complete platoon dispersion). Benefits can therefore be obtained by signal coordination, as was already recognised by the 1930s.1 Through coordination, it is possible in certain circumstances to establish a green wave, whereby a platoon of traffic may pass through a sequence of intersections without stopping. Alternatively, the risk of excessive queuing between two intersections may be reduced by coordination. The other benefits of coordination include: the attraction of traffic by green waves to major roads away from minor roads in environmentally sensitive (typically residential) areas; the reduction of speed variation on major roads, thereby improving road safety; and the improvement of the comfort and speed of public transport services by reducing their need to stop at intersections.
