Research On Variable Speed Limit In Highway Bottleneck Area

As a link between urban and urban traffic,the expressway is also an important carrier for cross-regional traffic in the same city.In recent years,the expressway has continued to expand,but it still cannot meet the growing demand for road traffic.The traffic congestion problem of the highway bottleneck section has become increasingly prominent.As a dynamic control method,variable speed limit is of great significance in improving traffic congestion and improving driving safety.Firstly,the thesis takes the bottleneck area of the highway as the research object,studies the structure type and characteristics of the bottleneck area,and proposes a variety of methods to judge the bottleneck area.On this basis,the paper studies the generation and transition process of traffic congestion in the bottleneck area.The variable speed control structure and control system are analyzed,and the various control elements determined by the variable speed limit lower speed value are analyzed.Secondly,the METANET model is used as the traffic flow simulation model of the expressway,combined with the change of traffic flow parameters during the peak period of the highway bottleneck section and the influence of variable speed limit on traffic flow,the model is modified to make it more in line with the real traffic flow state of the road,and combine the simulation data to calibrate the model parameters.Then,combining the experimental data to determine the variable speed limit control objective function,it is determined that the environmental benefits,that is,the carbon dioxide emissions from the vehicle exhaust emissions at a certain speed is large and the vehicle fuel consumption is low,and the total travel time of the road,and the total road traffic flow.In order to ensure the pro-activeness of the speed limit strategy,a feedback algorithm model based on the MPC algorithm for controlling the target-control strategy is proposed to optimize the speed limit value.Finally,taking the West Han Expressway as an example,the road Vissim simulation is established to calibrate the model parameters.Determining multiple control strategies based on variable speed limit control elements,combine Matlab program to simulate and analyze different control strategies.The results show that the implementation of variable speed limit can not only improve the road traffic operation,but also make the variable speed limit more reliable based on the preferred speed limit value of each control target.