Traffic Equilibrium in Congested Road Networks and its applicability

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The purpose of this study is to establish the way to analyze the traffic flow in congested road networks. Many approaches were tried and the following results were obtained.1. The travel time on congested link can be decomposed into the running time by non-congested flow and the delay at the end of link. The equlibrium flow and the delay can be obtained through the fixed demand traffic equilibrium problem with explicit link capacity restraints.2. As the numerical solution method of this problem, the Lagrange multiplier method and the interior penalty function method were proposed. The former is strict but unpractical in large scale network. On the contrary, the later is practical but rather approximate.3. Two traffic equilibrium models were formulated considering the interaction between user's route choice and traffic signal control. One of the model is to add the capability condition of traffic management at intersection. The solution of this model is equivalent to the equilibrium consistent with Smith's responsive control policy Po. The other model is to request the simultaneous solution of user's equilibrium problem and optimal signal setting problem. The equilibrium solution of this problem corresponds to the Nash equilbrium in game theory. The numerical solution method of these two models were proposed.4. The computer aided support system with respect to the equilibrium traffic assignment was made using personal computer. Efficient programs to compute traffic equilbrium were prepared. Colour graphic display methods to grasp traffic flow on road network and the way how to input the form of road network were developped.5. The above system was applied to the road network in southern part of Okayama prafecture. Through the computation, it was made clear that the estimate flows of the model fit well to the observed flows. But with respect to the reappearance of travel time, sufficient data were not obtained. That remains as the subject for a future study.