Travel Time Reliability Of A Road Network With Mixed Traffic Of Connected-vehicles And Regular-vehicles

The Internet of Vehicles environment(IOV)is the inevitable trend of future development,which will bring great changes.However,the intellectualization of the transportation system is not achieved overnight.The incomplete IOV environment which mixed with ConnectedVehicles(CV)and Regular-Vehicles(RV)is bound to appear.It is very important to manage and control the network in this situation.With the rapid development of urban transportation,travelers pay more and more attention to the travel quality and the fluctuation of travel time.The incomplete IOV environment may bring uncertainty to travel and traffic operation.Therefore,based on the road network mixed with CV and RV(abbreviated as mixed network),this paper analyzes the travel time fluctuation and the traffic operation state of the network under the incomplete IOV environment,and studies the travel time reliability of the mixed network.Firstly,the theoretical knowledge related to the research is sorted out and summarized.The car-following models used to characterize CV and RV,the CTM model for mixed network modeling and traffic assignment,and the traffic simulation platform SUMO for model verification are introduced.The influencing factors of travel time reliability are analyzed,the definition and calculation method of reliability are sorted out,and several commonly used indicators of travel time reliability are classified and summarized from different definition.Secondly,quantify the impact of vehicle interaction on traffic flow in the mixed network,and obtain the flow-density relationship diagram under different proportions of CV,and then the relationship between the macro parameters of traffic flow and the proportion of CV is obtained.On this basis,the classical model is improved and a CTM model considering the mixing of two types of vehicles is established to describe the traffic transmission law of the mixed network.Considering the difference of the traveler’s cognition of the network,the dynamic stochastic user equilibrium model is established and solved,and the travel time of the vehicle in the equilibrium state is output for reliability analysis.Thirdly,considering the influence of random factors,a comprehensive reliability index is proposed,which comprehensively considers probability index and deterministic index such as Buffer Time Index and Misery Index.Analyze the sample distribution of travel time in equilibrium state,determine the cumulative distribution function of path travel time through fitting,calculate the comprehensive reliability index,and then obtain the travel time reliability of path.On this basis,the travel time reliability model of the mixed network is established,taking the path as the unit,the OD pair and network travel time reliability are calculated,and the reliability calculation process of the mixed network travel time is proposed.Finally,based on the dynamic traffic assignment model of mixed network and the reliability calculation process,analyze travel time reliability of the example network.Based on the traffic simulation platform SUMO,the mixed road network simulation scenario is designed.The simulation results show that the model has high accuracy and the error is within10%.The comprehensive reliability index can comprehensively and systematically evaluate the reliability of travel time.The travel time reliability of network is affected by the level of demand,road structure and traveler’s route selection behavior.Increasing the proportion of CV can enhance reliability,but it is not necessarily positively related to the improvement effect.The results show that the improvement effect is the most obvious where the proportion of connected vehicles is 30% ～ 50%.The reliability is calculated by changing the demand level of the network,results show that the proportion of CV increased from 0 to 90%,and the reliability of the network increased by 13.45%、14.26% and 16.60% under low,medium and high demand levels,respectively,which reflects the advantages of CV in improving road performance and operating efficiency under traffic congestion.