Control Strategy Study Of Urban Expressway Ramp In Intelligent And Connected Environment

The transportation efficiency of expressway has an important influence on the smooth passage of urban traffic network.The research shows that the traffic jam and accidents are very easy to occur near the on ramp of the expressway.If it is not controlled,the traffic environment of the expressway may be further deteriorated,and the overall benefit of the urban road network will be reduced.Compared with highway,urban expressway shows different characteristics,such as more complex changes and discretization of traffic flow.All of these make the research of expressway traffic control face many problems,and some of the current expressway traffic control measures have some problems,such as low accuracy,single control objective and so on,the optimization result is not satisfactory.On the other hand,the development of intelligent networking technology has been widely concerned by scholars in recent years.Using the intelligent networking technology can obtain more accurate and stable traffic flow data in real time,and can guide the vehicle to drive according to the control instructions,so as to improve the traffic efficiency.But at present,the research related to intelligent networking technology is mostly focused on the microscopic angle,and there is no research from the macro perspective.Therefore,this paper takes the urban expressway ramp as the research object,and combined with the intelligent networking technology,puts forward the ramp control strategy under the intelligent networking environment.This paper presents an expressway ramp cooperative control system in the intelligent network environment,including the route decision system and the expressway ramp control system.It puts forward the improved road traffic impedance model in this paper,which provides the basis for route decision-making.It can be seen from simulation that this method can reduce the proportion of traffic entering the expressway during peak hours and conflicts in the merging area,improve the efficiency of the road network at the same time.At present,the variable speed limit control(VSL)and ramp control(RM)are commonly used to control the traffic flow in the bottleneck area,so this paper combines VSL and RM.For RM control,this paper improves ALINEA and uses PSO-WNN to predict the on-ramp demand of expressway in this cycle to solve the existing problems.In the aspect of VSL,this paper introduces the commonly used open-loop control,closed-loop control and predictive control algorithm,and proposes the framework of urban expressway ramp collaborative control strategy based on MPC by cooperating with RM.Then,aiming at the shortcomings of traditional METANET model and considering the influence of the combined control of VSL and RM,this paper proposes an improved METANET model,which can realize the feedback between RM and VSL.The effectiveness of the model has also been verified.Then this paper constructs the objective function of the collaborative control model and designs the genetic solving algorithm NSGA-II.In this paper,Lou Jiang expressway in Suzhou is taken as the simulation section,and VISSIM secondary development is realized through the cooperation of MATLAB and other software to simulate the intelligent networking environment and realize the control strategy.The paper adopts different indicators when analyzing the results.It shows that the proposed control method can reduce the total travel time by 20.59%,and can reduce the speed difference between adjacent roads by 34.07%,which improves the efficiency and safety of the urban expressway network.It can realize the coordinated control of the urban expressway and the ramp in the intelligent networking environment by adopting the control strategy proposed in this paper.It can also alleviate the traffic congestion of expressway,reduce the traffic pressure and improve the efficiency of urban expressway network.