Research On Complexity Model And Comprehensive Traffic Benefits Of Road Intersection Based On Automatic Vehicles

With the continuous increase of urban vehicle ownership,the traffic pressure of urban road intersections is becoming heavier,traffic congestion,environment pollution and other problems are becoming more and more,which seriously affect the normal work of intersections.Intersection has become the key node of urban traffic,and its operation directly affects the traffic efficiency of urban road network.At the same time,the rapid development of automatic vehicles(AVs)in recent years provides a new idea for intersection management.Therefore,based on AVs technology that has been put into practical application,this paper uses questionnaire,qualitative and quantitative methods to conduct a comprehensive research on driving safety and driving characteristics of AVs at intersections,which includes revealing people’s views on AVs,the influence of AVs on the complexity model,the effect of AVs on comprehensive traffic benefits and corresponding improvement measures at intersections.Firstly,this paper uses SP method to carry out a questionnaire survey on safety and comprehensive traffic benefits of AVs.The survey finds that most people would accept AVs and they hold that AVs will be popularized within 6 to 10 years,which could improve the traffic safety and efficiency at intersections,and reduce vehicle exhaust emissions,showing a good prospect for AVs.At the same time,some people are uncertain about the acceptability of AVs,and they are not sure about the comprehensive traffic benefits of AVs at intersections.Therefore,this paper uses SUMO simulation to study safety,traffic and environmental characteristics of AVs at intersections to verify people’s different views.Secondly,based on the fact that some drivers show uncertain attitudes towards the safety of AVs at intersections,this paper takes complexity coefficient as safety index and conflict probability as breakthrough point to study complexity model of non signalized intersections with different entrance traffic volumes under current AVs technology.With the help of SUMO simulation,This paper comprehensively revals and analyzes the influence of AVs on complexity model,finding that with the increase of the proportion of AVs,the probability of cross conflict and non cross conflict of motor vehicles show an inverted U-shaped trend,and the proportion of AV s corresponding to the peak value is between 0.5 and 0.7,which indicates that the complexity coefficient also shows an inverted U-shaped trend with the increase of AVs proportion.When the proportion of AVs is between 0.5 and 0.7,the complexity coefficient reaches the peak,which confirms the views of some drivers on safety of AVs.Although the conflict probability is increased,the range is limted.Compared with the pure Manual Vehicles(MVs)flow,the maximum value is 6.80%,and the minimum is only 0.79%,showing that the impact of AVs on traffic safety of the intersection is limited.We can reduce conflict probability and complexity coefficient of the intersection to improve the safety level through the optimization of intersection organization or vehicle technology.Then,based on the fact that some drivers show uncertain attitudes towards the comprehensive traffic benefits of AVs at intersections,this paper takes 6-4 and 6-6 intersections as research objects and selects seven evaluating indicators to study the impacts of AVs on the comprehensive traffic benefits under different phases and volumes,namely average travel time,average speed,average loss time,speed standard deviation,average waiting time,average waiting times and total emissions of five pollutants(CO2,CO,HC,PMx,NOx)per vehicles.It is found that although the impact of AVs on comprehensive traffic benefits of traffic flow in low peak period is limited at non signalized intersections and AVs are unable to improve the traffic and environmental benefits,they can improve the comprehensive traffic benefits in flat and peak periods.At two phase and three phase intersections,due to the current AVs technology is unable to avoid the dilemma and reduce the impact of conflict avoidance,the congestion caused by vehicles entering the dilemma and conflict avoidance makes the indexes of vehicle flow fluctuate abnormally in peak and flat periods,which reduces the improvement benefits of AVs and has a negative impact on the normal traffic of the intersection.However,except for the fluctuation point,the improvement effect of AVs on the comprehensive traffic benefits is still significant.At four phase intersections,while the improvement effect of AVs on traffic efficiency in low peak period is not well,AVs can improve the environmental efficiency in low peak period and the comprehensive traffic benefits in flat peak period and peak period.In addition,this chapter also uses the fuzzy comprehensive evaluation method to formulate the evaluation scheme and establish the evaluation model,which is convenient for the future traffic management to evaluate the intersection under the condition of AVsFinally,according to the research results of the complexity coefficient and comprehensive traffic benefits,this paper puts forward the improvement measures for the comprehensive traffic benefits of the intersection under the condition of AV s by using channelization diversion,vehicle road coordination technology and infrastructure improvement,so as to further improve the comprehensive traffic benefits of AVs at intersections.