A proposed model of extended coordination for the traffic light control at intersections

Abstract

The contemporary method for the coordination of urban intersections design for the same speed of approach of around 45 km·h -1 does not allow changes in the coordination speed based on faster changes of the required intersection capacity resulting from changed intensity of traffic during a day. However, the speed of traffic flow changes significantly with the road saturation. The coordination is often ignored in off-peak intensities, when the minimisation of the waiting times decreases the cycle length of light signaling equipment (LSE). However, this leads to changed green waves (in time), which means that the coordinated groups of vehicles pass the intersection at different times. Because of fixed constant distances between intersections, the preservation of the green wave might not be possible and even at a lower traffic intensity the number of cars stopping can increase, the waiting times prolong and therefore the traffic smoothness can be deteriorated. The model of extended coordination defines the dependence of duration of traffic lights controlled intersections cycle on the intensity of the coordinated entry, the speed of approach and the distance between the coordinated intersections. The length of the cycle defined this way improves the traffic smoothness by the coordination of traffic light controlled intersections also in the cases of unfavourable conditions for bidirectional coordination. © 2012 Springer-Verlag.