Coordinated Control Of Variable Speed Limit And Ramp Metering Of Urban Expressway Under Unexpected Traffic Accidents

Based on the summary of variable speed control and entrance ramp control research,this paper takes into account the number of traffic lanes occupied by sudden traffic events,the ramp regulation within the scope of the incident,the length of traffic events and so on.The classical METANET dynamic traffic flow model to make relevant improvements,so that it is able to reflect the traffic conditions under the urban expressway traffic flow operation.The coordination control model including the ramp control module and the main variable speed limit module is established.The genetic algorithm is used to solve the coordination control model and the example of the West Third Ring Expressway in the north of Suzhou is simulated.This paper has the following tasks:Establishment of variable speed limit and ramp coordination control system for expressway main line under sudden traffic accident.The corresponding functional modules are divided according to the different functional requirements of traffic incidents.This paper gives the framework of the control system for the urban expressway.Improve the METANET model with the effects of sudden traffic events.Based on the previous research results and the needs of the research situation,the METANET model of the macroscopic dynamic traffic flow model is selected.Improving the model to meet the actual traffic conditions of the expressway under the sudden traffic accident by analyzing the possible impact of the sudden traffic incident.Establishment of coordinated control model of urban expressway under sudden traffic accident The variable speed limit control and the inlet ramp regulation are embedded into the improved METANET model.The queuing length of the traffic on the traffic event is selected,and the sum of the total vehicle time and length is taken as the objective function and the coordination control Model of the system evaluation index.Solve the model and simulate and evaluate.The optimal solution of the coordinated control model is solved by using the genetic algorithm,and the example of the expressway of the West Third Ring Road in Beijing is simulated by MATLAB software.The results show that the urban expressway coordinated control model can effectively reduce the upstream queuing length of the expressway traffic accident event and reduce the total time consuming through the event area,so that the traffic density of the upstream section of the event changes more smoothly.