Study On Characteristics Of Traffic Flow In Basic Road Sections In A Connected Vehicles Environment

In recent years,the rapid development of wireless communication,positioning and sensing technology has produced the concept of an Internet of Vehicles,which is defined as an intelligent connection between vehicles and other vehicles and between vehicles and roadside infrastructure.It also represents an extension and expansion of a network based on the Internet.In a connected vehicles environment,a driver can receive timely information on the speeds of surrounding vehicles,distances,and turns,thus greatly enhancing the driver's decision-making ability and significantly decreasing reaction time.The vehicle interconnection technology cannot only improve road safety and reduce accidents but can also,to some extent,reduce vehicle headway and following distance,thereby increasing the traffic capacity of the road.It is of great significance to study the characteristics of vehicle traffic flow to alleviate the increasingly serious traffic congestion.In this paper,a typical connected vehicle scenario is designed to obtain the key traffic parameters in the actual road test.Based on this,we study the traffic flow characteristics such as the driver's reaction time,car-following,headway,traffic congestion,traffic capacity and so on,The specific research content is as follows:?1?According to the hardware and software needs to build a vehicle interactive environment experimental platform,introduced experimental preparation of the actual test of the driver,road and platform test.On the basis of collection characteristics of parameters on driver reaction time,expectation with the distance and headway,design scheme of the actual vehicle test is designed,which lays the foundation for the research on the basic road section of connected vehicles environment.?2?According to the different driving behavior,the driver reaction time is divided into simple reaction time and complex reaction time.Based on the Gaussian Mixture Model?GMM?,the reaction time characteristics of the traditional environment and connected vehicles environment are analyzed.Study results show that simple reaction time is shortened by7.94%,complex reaction time is significantly shortened 25.79% in the connected vehicles environment.Furthermore,the population standard deviation of driver's reaction time is shortened by 32.99% and more concentrated,and the effect of speed on reaction time is not significant in the connected vehicles environment.?3?Review the classical theory of car-following to determine the physiological-psychological Widemann74 model for research basic model in connected vehicles environment,and analyze the core threshold only three: static parking distance AX,safe braking distance BX and maximum follow-up distance SDX.The underlying key parameters AX_add ? BX_add ? BX_mult related to driver's reaction time and following distance from the car.In addition,follow-up distance threshold is reconstructed and calibrated based on data acquisition of real vehicle test in vehicle interconnection scene.Furthermore,the modified Widemann74 model was established in the vehicle interconnection environment and to analyze driving behavior characteristics in connected vehicles environment and traditional environment.The results show that the connected vehicles environment is significantly lower than the traditional environment.?4?Aiming at the problem that the common main distribution model of headway can not describe the actual headway of the basic section of road,the traffic flow is divided into the following state and the free flow state based on the idea of the two divided.And mixture model of headway distribution is established,and the data of Chongqing expressway are used to verify.Then,characteristics of car-following state of saturated flow were analyzed based on vehicle headway data of the vehicle under different operating conditions collected by the vehicle interconnection platform in traditional environment and connected vehicles environment.The results show that the saturated flow headway is shortened by 26.69%,headway of strong following state shortened by 41.36%,headway of weak following state shortened by 34.42%,and dispersion is reduced in connected vehicles environment compared with the traditional environment.?5?Based on parameters such as driver's reaction time and expected distance of the vehicle in actual vehicle test of the connected vehicles scene,driving key parameters AX_add?BX_add and BX_mult of VISSIM simulation platform are calibrated,and traffic state of road basic sections are simulated in connected vehicles environment and traditional environment,and the frequent and occasional congestion of formation and diffusion are analyzed.The results show that the vehicle congestion time is significantly reduced,shortening by 20.48%,and the occasional congestion is random,the crowded time is slightly less than the traditional environment.?6?Basic traffic capacity model of the connected vehicles environment is established based on headway and distance of the saturated flow in actual vehicle test.The possible capacity model of the connected vehicles environment is established based on VISSIM simulation platform.The results show that the basic capacity of connected vehicles environment is higher 30% than traditional environment,and the possible capacity is higher 24% than traditional environment.