Study On Acceleration Characteristics Of Interchange Ramp Based On Vehicle Road Test

Interchange is an artificial structure in which two or more roads cross each other on different planes and connected by ramps,which is an indispensable part of expressways and urban roads.As an important road structure,interchange makes traffic flow in all directions on different elevations through ramps,which reduces or eliminates conflict points,ensures traffic safety and effectively improves traffic capacity.With the continuous increase of funds for transportation infrastructure construction and the continuous increase in the number of motor vehicles,there are more and more interchanges in order to eliminate traffic congestion and traffic congestion.At the same time,the hidden danger of traffic accidents is also gradually increasing,and the proportion of traffic accidents on the interchange is increasing year by year.Improving the traffic safety of interchange has attracted the attention of many researchers.In this paper,vehicle road tests are carried out on three kinds of interchange ramps.According to the speed curve of passenger cars on the ramp,the speed change modes of three types of ramps are analyzed,and the characteristics of longitudinal acceleration in the stage of speed change are studied.the statistical distribution characteristics of longitudinal acceleration of circuitous ramp and S-shaped ramp are analyzed,and the driving comfort of ramp is evaluated based on longitudinal acceleration.Then the lateral acceleration characteristics of three types of ramps are studied.The variation characteristics and distribution law of lateral acceleration of ramp minibuses are analyzed.The changes of lateral acceleration on three types of ramps all show three stages,namely,turning growth stage,stable stage and exit decreasing stage.Based on the statistical analysis of the lateral acceleration distribution of different types of drivers’ ramps,it is found that the lateral acceleration of male drivers is higher than that of female drivers.There are some differences in the distribution of lateral acceleration among different style drivers in different stages.the average value of lateral acceleration of angry drivers is higher than that of adventurous drivers,and the distribution of lateral acceleration of adventurous drivers is larger than that of adventurous drivers.the distribution is more discrete.According to the analysis of the influencing factors of lateral acceleration in the stable stage,it is found that there is a positive correlation between velocity and the peak value of lateral acceleration,while gender and driving style have no significant influence on the peak value of lateral acceleration.The statistical distribution characteristics of the lateral acceleration of the ramp are analyzed by the cumulative frequency curve,and the driving comfort of the ramp is evaluated based on the lateral acceleration.Finally,the ramp driving behavior of interchange is analyzed based on the characteristic parameters of driving behavior.According to the threshold boundary of safe driving behavior,the dangerous driving behavior on each ramp is counted,the dangerous section grade is determined according to the proportion of dangerous driving behavior on the cross section,and the distribution of dangerous driving behavior on three types of ramps is analyzed.the section with high incidence of dangerous driving behavior on the ramp is determined.The high incidence area of dangerous driving behavior is the ramp curve speed change stage.In the operation and management of interchange,the speed guidance at this stage should be increased to reduce the occurrence of dangerous driving behavior.The research of this paper provides basic data and scientific basis for operation management,safety improvement,simulation model modification and design code revision of road interchange.This paper is supported by the National Natural Science Foundation of China and the Applied basic Research Project of the Ministry of Transportation.