Modeling And Analysis Of Urban Traffic Overflow Control Based On CTM

With the vigorous development of social economy and the continuous growth of car ownership,the construction of urban transport infrastructure can not catch up with the growth of traffic demand,resulting in increasingly severe traffic congestion.Traffic overflow is a common congestion in urban road network.Its adverse impact on traffic safety and the loss of social and economic benefits can not be ignored.Therefore,it is necessary to solve the problem of traffic overflow and improve travel efficiency and traffic safety.Cell Transmission Model(CTM)is a macroscopic traffic flow simulation model.Because of its flexible traffic system modeling method and efficient computing efficiency,CTM has been applied in many fields such as dynamic traffic assignment,traffic system simulation,dynamic traffic guidance and so on.Petri Nets(PN)is a powerful tool for modeling concurrent,conflicting,stochastic and discrete characteristics of distributed systems,which is very suitable for analyzing urban traffic systems.Based on the application of CTM and Petri net in urban traffic system,this paper proposes a new solution to the problem of traffic overflow on urban trunk roads.Specifically,the research contents of this paper are as follows:1.Establish a CTM model of traffic flow at two intersections of urban trunk roads.Specifically,based on two-phase and four-phase signal control,different cell structures of urban arterial roads are divided firstly.Secondly,the CTM construction method of urban arterial traffic flow under two kinds of signal control is introduced.Finally,an example is given to simulate the traffic flow propagation process of urban arterial roads.At the same time,the change of traffic flow density under different input and different phase differences is analyzed.The analysis results accord with the basic CTM triangle diagram,which proves the correctness of the simulation method and reproduces the operation process of traffic flow.2.Establish a Timed Colored Petri Nets(TCPN)model for urban trunk road traffic overflow control system.Specifically,the TCPN sub-models of intersections,signal lights,controllers,traffic flow and other entities in the system are established separately,and the logical relationship among the sub-modules is accurately described through the layering and connection between the models.3.Simulation and analysis of TCPN model of urban trunk road traffic overflow control system.Specifically,traffic flow estimation is based on the CTM model established above,which provides the initial value for the TCPN sub-model describing traffic flow.Then,by simulating the critical conditions of traffic overflow phenomenon caused by three different situations in the TCPN model,corresponding control strategies are proposed,and simulation and analysis are carried out to verify the proposed control strategy and traffic overflow control system is effective in solving overflow problems.