Traffic Overflow Coordination Control And Its Simulation Study On Urban Arterial Road

The rapid development of economy promotes the pace of urban modernization, and makes people’s trip mode more diversified and high-speeding. In the1980s, private cars began to emerge in China, and car ownership broke ten million up to2003, just using three years to break twenty million. At present, our car ownership has been more than one hundred million. This huge number doesn’t just mean more convenient and fast, but generates many problems such as traffic jam, traffic accidents, environment pollution and noise, which have declined people’s life quality.Urban arterial roads are the framework and main artery of urban road traffic network, which undertake huge traffic pressure. Traffic jam is easy to occur on arterial road due to its large traffic flow, many traffic routes, leading traffic control and serious coexistence6f people and vehicles. In these years, the phenomenon of "traffic overflow" happens repeatedly."Traffic overflow" is the consequence of the contradiction between supply and demand of traffic, and is the spatial dimension expression of oversaturated traffic flow’s negative effect. Its space expression is that the queue length of downstream intersection occupies the whole road space, and its time expression is that the vehicles from the upstream intersection can’t drive to the downstream intersection resulting in the waste of green time. If the effect continues, it would spread like the water flow in the pipe, from one intersection to the intersections around to the whole traffic network, which is very serious. So it has very big practical significance to study the occurrence mechanism and control strategy of "traffic overflow".The vehicle queue length is the main factor of traffic overflow, and is the starting point to study its occurrence mechanism. In the paper, it analyzes the section vehicle queue length base on the arrival time of the motorcade to the downstream intersection, and it gives the calculation formulas of the retention queue length and the stop queue length, combing the modified traffic wave model. Then it establishes the calculation model of the section maximum queue length, and uses the microscopic simulation software VISSIM to verify its effectiveness. From the concept of "traffic overflow", we know that, if the queue length is greater than the section length, then the phenomenon is easily to occur. Base on the thought, the paper builds the queue length limiting condition model.Vehicle delay is one of the traffic control strategy evaluation indexes, which is often used as important measure index of models by specialists and scholars. Referring to a large number of literatures, we found that the models involving in original and improved were mainly aim at unsaturated coordination route and oversaturated intersection. In view of "traffic overflow", the paper builds the minimum delay phase difference optimization method which is on the basis of timing theory delay model and suitable for oversaturated coordination route. Then, the result of the queue length limiting condition model is used as the constraint condition of the method, to solve the optimal phase difference which can avoid traffic overflow to occur as well as minimize the delay time. The model’s effectiveness is also verified by VISSIM.When making the urban arterial traffic overflow coordination control strategy, the paper introduces the definition of the road network, the signal timing of the intersection, the choose way of the common signal cycle, the optimization method of the phase difference, and the example simulation in detail. In addition, the paper improves the typical F-B signal timing method to make its application more wide. At last, the paper embeds the model to the overflow control system. Some innovation points are proposed in the paper, and however, there are some shortcomings. The paper gives a summary of the whole work and an outlook to the next study at last.