Study On Optimization Methods Of Auxiliary Road Controlling Parameters Of Urban Expressway Off-ramp

Urban expressway is the artery of the city traffic system, but with the increasing of transportation demand, traffic congestion takes place again and again, influencing people's life seriously. Take Beijing to instance, there are traffic congestion often. There are some reasons to urban expressway traffic congestion, and one of main reason is that cars of off-ramp queue come back to the mainline of the urban expressway. Currently, one of the methods used to alleviate traffic congestion is to improve traffic management and control in urban expressway system.The dissertation is based on the project of Qingdao Hisense Network Technology Co., Ltd."Study on the Optimization Methods about Controlling Theory and Algorithm of Urban Expressway Ramp"and the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE"Study on Theory of Controlling Urban Expressway System". By researching urban expressway off-ramp and controlling the car in auxiliary road, the dissertation puts forward optimization methods of auxiliary road controlling parameters of expressway off-ramp, which may provide the reference for traffic management and control in urban expressway system. The research is composed of interrelated chapters as follows:At first the dissertation introduces the supported projects and the research backgrounds, sums up the off-ramp control methods of freeway, and then analyzes the status of constructing and planning and the present methods of Beijing expressway off-ramp. Then the dissertation puts forward its study contents, significance and frameworks.The second part of the dissertation studies the foundation knowledge of ramp control. The dissertation illuminates the characteristic of expressway, and summarizes the reasons of car queue that is mainly affected traffic offer and supply besides some reasons that are put forward according to the actual state of expressway off-ramp, which is mainly due to the different types off-ramp and adjacence road. By measuring off the types of off-ramp, the dissertation puts forward the methods of expressway off-ramp, closing the expressway off-ramp and controlling auxiliary road near expressway off-ramp. The dissertation suggests some cases to close expressway off-ramp. Base on the types of the different junction between interior and exterior of expressway off-ramp, the dissertation summarizes three types: control auxiliary road of single off-ramp, coordinated control between on-ramp and off-ramp, coordinated control between auxiliary road near off-ramp and intersection. The dissertation mainly study on control auxiliary road of single off-ramp and coordinated control between auxiliary road near off-ramp and intersection, the rest type does not deeply discussed. For understanding the basic concept of traffic control, the dissertation simply introduces the concept signal timing parameters of urban traffic control, including cycle length, green time, etc. and looks back three delay models.The third part of the dissertation studies optimization methods of auxiliary road controlling parameters of single off-ramp. The part firstly analyzes the current problems of Beijing off-ramp control and the congestion reasons of the urban expressway off-ramp, then gets hold of the most same reasons and the different congestion degree because of the different junction. The dissertation uses the same control method, separately puts forward optimization methods of controlling parameters of auxiliary road with spur track and without spur track. For the type of auxiliary road without spur track, the part sets up the model of cycle length and green time, and the parameters of model can be separately calibrated according to the types between off-ramp and auxiliary road. For the type of auxiliary road with spur track, on the basis of the front optimization methods of controlling parameters of auxiliary road, optimize the cycle length and green time. Based on field data of Beijing Xueyuan Bridge off-ramp, the dissertation calibrates the model parameters to compare with optimization methods. The dissertation deduces the total average delay of off-ramp car and auxiliary car between controlling auxiliary car and without controlling auxiliary road car, and result shows that optimization methods of auxiliary road controlling parameters can reduce the total average delay.The four part of the dissertation studies coordinated control methods between auxiliary road near off-ramp and intersection. The part firstly analyzes the mainly reasons of off-ramp congestion that is what the cars of off-ramp and auxiliary diturbe each other besides traffic offer exceeds road traffic capacity when expressway off-ramp is near intersection. Then the dissertation uses the methods of coordinated control between auxiliary road near off-ramp and intersection. Firstly, compute the signal timing parameters according to optimization methods of auxiliary road controlling parameters of single off-ramp. On the basis of fixed cycle length, change the red time and green time of intersection to adjust signal timing parameters of intersection to arrive at object of off-ramp car driving firstly. If intersection condition restrict, only adjust the signal timing parameters of auxiliary road to assure off-ramp car priority. And the dissertation computes the maximum red times and the minimum green times of intersection. Among microcosmic traffic simulation software, VISSIM, is ideal in simulating, and the result shows that coordinated control methods between auxiliary road near off-ramp and intersection is good and the methods can improve the flow and speed of off-ramp and shorten travel time of off-ramp cars.In the end, the dissertation summarizes the study works, analyses the findings and achievements, concludes the innovation points, and brings forward the issues and contents for further study.