Phasing of Traffic Lights in Urban Intersections

Abstract

In this chapter, the phasing of traffic lights in urban intersections is introduced and discussed applying the graph theory concepts. At first section, some concepts such as traffic streams, vehicle or pedestrian flows, and compatible streams or streams which are in conflict, are introduced. Accordingly, from the viewpoint of graph theory, two approaches are introduced for phasing of traffic streams. The first approach uses the concept of conflict graphs, and the second one uses the concepts such as circular chromatic number and star chromatic number of graphs, developing two procedures of phasing of traffic streams in urban intersections. In addition, these two procedures are compared based on the performance index of total length of complete traffic period which should be optimized.