Intelligent Switchable Ramp System And Coordinated Control Method For Urban Expressway

The urban expressway is the road with the highest technical level in the urban road network,only connected to other roads through ramps.The urban expressway with the characteristics of fast speed and high traffic capacity undertakes long-distance travel in the city and is the skeleton of the urban road system.With the development of the national economy,the continuous expansion of the city,the continuous increase of car ownership,the traffic demand for urban expressway is gradually increasing.The traffic capacity of the ramps arranged along the urban expressway is often difficult to match with the high traffic capacity of the urban expressway.Ramps with lower traffic capacity have become the bottleneck of the expressway system,resulting in a reduction in the service level of the expressway and negatively affecting the operation of the surrounding road network.Therefore,the innovative design of urban expressway ramp and reasonable traffic management and control strategies are effective methods to improve the efficiency of the overall urban road system.In order to cope with the high traffic demand during peak hours,the paper adopts an intelligent switchable ramp system to optimize the urban expressway traffic state by means of coordinated control.In the first part of the paper,the composition and working principle of the intelligent switchable ramp system and geometric design of single switchable ramp are introduced.According to the characteristics of the intelligent switchable ramp,its applicable conditions are analyzed,and methods to reduce the negative impact of the continuous change of the intelligent switchable ramp state on the driver are proposed.Then,based on the characteristics of the urban expressway and the NS model,the cellular automata model of the urban expressway is proposed.The impact of the intelligent switchable ramp operation is analyzed on the main road.Finally,in order to determine the location of the intelligent switchable ramp,the Kmeans clustering algorithm is used to perform cluster analysis on the urban expressway example data derived from the VISSIM simulation software.The cluster centers under the three traffic states of unblocked,congested and bottleneck provide a basis for the layout of the intelligent switchable ramp.Based on the cellular automata model,the intelligent switchable ramps coordinated control optimization model is established to optimize the traffic on the urban expressway.Model parameters are solved by genetic algorithm.The simulation results show that under conditions of high traffic demand,the intelligent switchable ramps coordinated control adopted in the paper has an optimizing effect on the traffic state of the urban expressway,which can alleviate the traffic congestion in the bottleneck section,and adding multiple intelligent switchable ramps has a more significant optimization effect than adding multiple traditional fixed ramps.