Urban Traffic Control centres (UTC) fill two main tasks: surveillance and traffic control. Fixed-time, as well as adaptative (SCOOT (1)) UTC systems are not often well fitted to process oversaturation. This lack can be explained by the complexity of the traffic congestion in urban areas: expanding queues can induce new blocking of junctions giving free-flow traffic on links formerly congested; saturation streams of independent origin can merge; 'saturation cycles' can form in the network. All these phenomena bring about a great unbalance in the data used for real-time selection or adaptation of traffic signal plans: vector choice algorithms lead in some cases to the choice of an 'off-peak hour' signal plan scheme. Moreover, the real causes of congestion can disappear from the actual context reproduced by detectors, although they still remain. This last statement makes us doubt about the future of quantitative methods based on optimization criteria.
Surveillance and congested traffic control in Paris by expert system
Ueberwachungs- und Ballungsverkehrssteuerung in Paris durch ein Expertensystem
1986
4 Seiten, 2 Bilder, 1 Tabelle, 8 Quellen
Conference paper
English