| With the increasing development of society and economy, the traffic congestion is gradually becoming one of the most serious social problems currently, so it's very necessary to study on various strategies and techniques which can solve traffic congestion. To alleviate congestion in the urban traffic, both expanding the traffic capacity and controlling the gross traffic demand were taken. In this paper, the study put emphasis on strategies and techniques of traffic control and traffic guidance on the aspect of dynamic traffic management to disperse congestion timely and alleviate the negative effect of congestion as much as possible. The research provides important theoretical significance and value in practice .The thesis investigates the strategies and technologies for dispelling urban traffic congestion based on the project of the Key Theories and Simulation Technologies of Dynamic Traffic Management and Control in Urban Road Network, funded by National Natural Science of China under grant 50338030.Traffic control is an effectual means in microscopical control of traffic stream. When traffic congestion happens, it can control the related intersections, divide up traffic stream of different direction and keep traffic order. The value of traffic guidance is to provide different traffic information to travelers in order to avoid traffic congestion on the basis of traffic condition and redistribute the traffic volume in large-scale of the road network. When the traffic capacity is close to be saturated in the sections of the road network or there are traffic accidents, the local congestion will happen, and then the dynamic traffic management and control will be helpful. So the dissertation chooses both of real-time management technology as research target. The details are as follows:1) The related theory of traffic congestion, status quo of traffic control and traffic guidance. The classification and the causation of the traffic congestion are presented, the congestion in this thesis is defined. The status quo of traffic control and traffic guidance is discussed. The strategies of traffic control have still in theory at present. By comparing K shortest path algorithms and dissimilar path algorithms, they can't meet the needs of the traffic guidance. Finally,the choosing indexes that evaluate the performance of traffic control and traffic guidance are presented.2) The technologies and strategies of traffic signal control under the condition of local congestion. Three strategies under local congestion are presented for isolated signalized control. The techniques of signal control are discussed from two aspects of signal phase optimization and the length of green time control. The strategy of red wave and green wave coordinated control for the upriver and downriver intersection of congestion direction is calibrated and tested3) The technologies and strategies of traffic guidance under the condition of local congestion. The strategies of traffic guidance are proposed and the K optimal path which is the emphasis content of this part is educed. Based on the characteristic of traffic guidance, three types of dynamic K optimal path are proposed. On the groundwork of Iterative Penalty Method, estimating index of dissimilar path which adapts to route optimization is proposed. A dynamic K optimal path algorithm which serves traffic guidance is designed using the idea of MD*. The algorithm is primary tested by constructing road network.4) The strategies of combination for traffic control and traffic guidance under the condition of local congestion. First, the necessity and feasibility of their combination have been considered. Three strategies of their combination are presented and simulation analysis is performed using the emulation software. Results show that this kind of combination is more helpful.In the end,the dissertation summarizes the finding and achievements and points out the issues for further research . |
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