Chain Reaction Models And Numerical Simulation Of Vehicle Queuing

With the rapid development of social economy and the increasingly deepen of urbanization process, the number of urban population and the life quality is increasing day by day. so the quantity of motor vehicles in the city is sustained growth. At the same time, the growth rate of urban car ownership is far more than the speed of the construction of urban road, which causes traffic congestion phenomenon more and more frequently. So the operating efficiency of urban transportation system is impacted seriously, and the further development of the urban socio-economic is restricted. Therefore, the problem of traffic congestion has become one of the key issues to be solved in large-and-medium-sized cities.Essentially, the problem of traffic congestion is caused by vehicle queuing formation process, so researching the internal mechanism of vehicle queuing formation is particularly important for solving traffic congestion problem. This thesis, relying on the National Natural Science Foundation-funded project "Study on chain reaction mechanism of road link jam in urban traffic network", is mainly based on the nuclear chain reaction thought, and vehicle queuing process is described in a whole new perspective. In this thesis, a single-period and multi-period vehicle queuing models based on nuclear chain reaction are established, then using those models to describe vehicle queuing process in adjacent intersections.This thesis is divided into six chapters. The first chapter summarizes the existing research about vehicle queuing problem. The second chapter introduces the concept of the chain reaction, and the chain reaction process of nuclear fission and traffic queuing are analyzed, and the similarity’ between them is found. The third chapter compares nuclear fission to chain reaction of vehicle queuing. Then a vehicle queuing model system is presented based on nuclear chain reaction thought. In this thesis, firstly, the similarity between vehicle queuing process and nuclear fission chain reaction is described. According to the principle of nuclear chain reaction, a single-period vehicle queuing model system is established, including vehicle queuing formation model, vehicle queuing dissipation model and vehicle queuing model for signalized intersection. By using the field survey data from a typical link in Dalian city, vehicle queue formation and dissipation models were validated. Also, the numerical simulations for traffic streams under different conditions were made by applying MATLAB software. Based on the simulation results, the sensitivity of the propagation speeds of block and dissipation signals to arrival flow rates and running speeds was further analyzed. The fourth chapter, to make models much more universal, multi-period vehicle queuing model system is established, including traffic flow dissociation model and traffic flow compression model. Multi-period numerical simulation is made to exam model’s stability. In addition, after the model derivation, the signal propagation of vehicle queuing chain reaction model and the wave velocity propagation of traffic wave model have consistency, although the two models point respectively from micro and macro perspective. The fifth chapter, given the reality of urban road network, there are a large number of intersections, so vehicle queuing chain reaction model used in adjacent intersections is discussed. By means of numerical simulation, the effect from traffic flow parameters and road length to vehicle queuing process is analyzed. The sixth chapter summarizes the main contents and results of this thesis.This thesis describes chain reaction phenomenon of vehicle queuing process from a new perspective, and proves chain reaction models of vehicle queuing. The results indicate that the proposed models have a higher precision, which can be used to calculate the propagation velocity and boundary of the chain reaction of vehicle queuing, and explain the internal mechanism of vehicle queue formation and dissipation on a link with a single lane. The research achievements can offer a novel idea and method for studying traffic queue, provide a foundation for explaining the principle of the chain reaction mechanism of road link jam. and give a theoretical basis for solving urban traffic congestion and jam problems.