Study On Prediction And Application Of Operating Speed Of Combined Horizontal And Vertical Of Curves On Mountain Highway

With the rapid development of national economy,the length of highway in mountainous areas increases year by year.At the same time,the problem of highway safety in mountain areas is becoming more and more prominent,and the steep road section with sharp curve is a typical feature of mountain roads.Therefore,it is necessary to study the safety of mountain roads.Whether the design of road alignment is reasonable or not will directly affect the road safety.At present,the highway alignment design method based on the design speed in China will cause the route to meet the design standards,but it cannot meet the driving needs of drivers.As a result of the action of drivers,road alignment,vehicle performance and traffic environment,operating speed is an important index of road safety audit.Therefore,it is of great significance to establish an accurate and effective prediction model for the operating speed of the combined horizontal and vertical of curves of mountain roads in order to guide the linear design of mountain roads and safety audit.From the point of view of man-vehicle-road system,this paper firstly analyzes the factors affecting the traffic characteristics and operating speed of mountain roads,and interprets the concepts of different speed such as inertia operating speed.The Metro Count 5600 traffic detection equipment was used to observe the speed of the section at the curve entrance,middle point and exit of the curved section of the combined horizontal and vertical of curves of the secondary mountainous road.The speed of the section was calculated based on the distribution test results of the section speed.Secondly,the principle of section division is put forward based on the preliminary analysis of section speed.By means of partial correlation analysis and factor collinearity diagnosis,the road alignment factors affecting the operating speed are screened,and the change law of independent variables is determined.Based on the method of multiple nonlinear regression,the basic prediction model of the operating speed of large and small cars at the curve midpoint and the curve outlet of the curved section is constructed,and the validity of the model is tested by statistical method.Considering the driver’s visual distance,road side environment,intersection density and other factors,the basic model of operating speed was modified,and the final prediction model of operating speed of vehicles in the combined horizontal and vertical of curved was determined.The accuracy of the model was verified by comparing the predicted value with the measured value.Finally,a method for evaluating highway safety in mountainous areas based on the coordination index,dispersion index and stability index of operating speed is proposed,and the safety audit of G108 and G244 sections is carried out.