Car-following Characteristics Analysis And Safety Control Study Of Super-long Tunnels On Plateau Expressways

As an important part of the road system,the tunnel has a large difference in the internal and external driving environment due to its special tubular structure.Although the accident rate of the tunnel section is low in terms of the number of accidents,the accident severity is even more serious.High,its traffic accident pattern is mainly rear-end.At the same time,in China,especially in the plateau area in the southwest,there are many tunnels and strong illumination.Due to the constraints of operating costs and other factors,it is difficult to meet operational security requirements in most cases.As the vehicle is driving through the tunnel entrance and exit areas,the drastic changes in the illumination of the light will cause the driver to have a "visual shock",which makes it impossible for the driver to judge the driving environment in front,and the illumination in the plateau is comparable to that in the plain.The area is more intense,and this change in illumination will have a more serious impact on the driver.In this paper,we study the characteristics of the high-speed expressway tunnels and the risk of driving,optimize the speed limit value of the tunnel section and set the traffic facilities as the target.Through the real-time car-fighting test in the special tunnel of the Yunnan-Guizhou Plateau,the driver can follow the data and eyes.The illuminance change data was collected to explore the vehicle following characteristics of the plateau expressway section and the driver's driving decision behavior,and further compare with the driving characteristics of the plain long tunnel section to analyze the difference.From the perspective of vehicle speed and heeling distance,the risk assessment model of the highway expressway tunnel is constructed to evaluate the safety of the expressway section of the plateau expressway.Since the traditional method for determining the speed limit of tunnels and the traffic management facilities are difficult to meet the traffic safety requirements of the plateau tunnel sections,the differences between the plateau tunnels and the plain tunnels should be considered,and reasonable speed limit values and corresponding management policies should be established for their characteristics.Therefore,based on the driver's partial utility optimal concept in the car-following process,the driver's local utility optimal driver's dynamic decision-changing car-following model is constructed through the safe followup distance model,the driver's perceived speed model and the driver's decision model.By simulating the optimal decision-making behavior of the driver during the driving process,the optimal speed limit value of each section of the tunnel is determined,and the reasonable setting of the tunnel safety facilities is given.The work of this paper mainly has the following four aspects:(1)From the aspects of driver,vehicle,road,tunnel environment,driving characteristics and safety,the effects of various factors on the traffic safety of tunnel sections are analyzed.Combined with the characteristics of tunnel sections,the differences between tunnel sections and ordinary open sections are analyzed.(2)According to the purpose of the experiment and the research needs,the real vehicle test plan for the plateau expressway tunnel was designed.According to the research goal,the driver's car-following data is collected,and the segmentation-clustering method is further used to divide the section of the plateau expressway into 6 segments according to the characteristics of the speed of the car-fed and the speed of the following,and the illumination of each segment.Data processing is performed on the following characteristic data.(3)Based on the vehicle data collected by the actual vehicle test,the vehicle following characteristics data and illuminance change data of the expressway section of the plateau expressway,and according to the results of the division of the plateau expressway section,analyze the variation of the vehicle speed,the following distance and the illuminance of each section of the tunnel,and further Combined with other scholars' research results on the characteristics of plain tunnel driving,the differences in driving between the plateau and plain tunnel sections are analyzed by reference.Based on the vehicle acceleration and the following range,the vehicle risk coefficient model is constructed to evaluate the driving risk of the plateau expressway section.(4)The driver's decision-making behavior of different sections of the plateau expressway tunnel was studied from the driver speed of the plateau expressway tunnel--the selection characteristics of the following range,the speed of the following speed and the driver's acceleration decision-making behavior,and the driver was established.Vehicle speed-following distance selection model and driver acceleration and deceleration decision model.The optimal concept of driver's local utility in the process of car-following is proposed.Based on the safety follow-up distance model,the driver's speed perception model and the driver's decision-making model,the driver's local utility optimal driver's dynamic decision-following model is constructed.The constructed car-following model can better simulate the driver's car-following process of making the best decision in each driving state,and use the maximum value of the simulated vehicle speed on each tunnel section as the speed limit value of each section of the plateau expressway tunnel.