Hierarchical Strategies for the On-Line Control of Urban Road Traffic Signals

This paper examines the problem of dynamic optimisation of urban road traffic networks with a view to applying on-line control. From this point of view, the problem of the rush hour is quite distinct from that of the off peak period due to the different time scales involved. In the present paper, hierarchical strategies are developed for both the peak and the off peak periods. Due to their modest computational requirements, the strategies could enable optimal on-line control to be achieved. Simulation studies for both undersaturated and oversaturated systems illustrate the approach.