Research On Signal Control Method Of Bottleneck Intersection

With the increasing development of urban economy and expanding scale, urban traffic congestion problem becomes so seriously that people's daily life and social stability are deeply influenced. Intersections which are set as the main urban transportation hubs are the potential traffic capacity bottlenecks. Therefore, the reasonable controls for the intersections are thought to be both the important methods of alleviating traffic jam and the key to the research of urban traffic congestion.At first, the generating mechanism of intersection traffic bottlenecks is analyzed. By using the traffic-wave model in classifying queue types, the regular patterns of influence to the traffic capacity of the road and intersection from various queuing types are discussed. And calculation model, which shows that queuing upriver leads to the loss of the traffic capacity of the upper intersection is given. Finally, the course of spread of jam queue upriver from bottleneck junction is demonstrated through numerical example.Secondly, on the basis of the analysis in the generation and diffusion mechanism bottlenecks, a special kind of super-saturation control method is proposed, which is the bottlenecks control. According to the request of data-acquisition, and considering the applicable conditions and scope, corresponding detector layout scheme is proposed. The paper introduces the system structure and data process, finds out the shortage of the previous bottleneck trigger and end conditions, proposes the concept of rolling-time share and gives the improved bottleneck control trigger and end conditions, improves the sensitivity and reliability of trigger and end conditions.Again, based on relationship of traffic demand and supply in each phase, the traffic condition can be sorted into nine kinds. According to different states, three kinds of bottleneck control methods are proposed:demand-control, supply-control and coordination-control, applicable conditions of different methods are studied. Point to the either signal control mode or multi-port coordinated control mode of intersection, the single point bottleneck control method and coordination bottleneck control method are proposed separately. In single point control, on the basis of analysis of the road structure, green time distribution model of "comprehensive queuing strength", which is comprehensively considered of the road recourses bottleneck junction, is established. In coordinated control, after the bottleneck area is divided into two parts, the methods of phase difference and balancing pressure are used to adjust the internal traffic flow in order to make the whole traffic branch area achieving optimal situation. And the transition algorithm which is between the ordinary algorithm and coordination algorithm is considered to make the whole control algorithms smoother. Finally, through the simulation of several control strategy of timing scheme, the validity of the proposed algorithm is proved.In the end, the main work and achievements are summarized and concluded, and the existing problems and future research content are pointed out in the paper. The research which shows good practical value can be used in preventing and mitigating intersection traffic bottlenecks and so on. But some details still need more improvement, such as the determination of the trigger and end threshold of the bottleneck control over all the conditions, which just gives advisable values. More reliable theory should be studied in order to gain better control effect in practical application.