Study On The Operating Speed Of Continuous Longitudinal Gradient About Mountain Area Freeway

With the implementation of the present national highway network, the focus of highway construction shifted to the mountain area from the large and medium urban area. Because of the limitation of some factors, such as the terrain, geological conditions and the difficulties of environment protection, the mountainous area have larger and longer slope or combination of the slope. It brings greater impact on level of service and traffic safety in freeway because the speed of vehicle driving up is lower than much and the speed of vehicle driving down increase excessively quickly. This research topic emphatically conducts the research to the operation speed.First of all, based on the result of experiment and the investigation, combining with the development tendency of freight vehicle in a period time of future and the analysis of accident vehicle type, it has determined the leading vehicle type. Then the characteristics of leading vehicle type are put forward through the research of operational characteristics on the section of longitudinal slope. And based on massive measured data, the characteristics of the operation speed are analyzed when the freight vehicles are drove on the section of longitudinal slope.Next, the theoretical model to calculate the operation speed at Sections with Particular Longitudinal Slopes using the theoretical formula. We selected loaded 10t dongfeng heavy freight vehicle as representative vehicle type, have done slip gear and coasting experiments on flat load and accelerating performance tests. With vehicle dynamics theory, we have established a vehicle operation speed experimental model at sections with uphill using regression analysis method.Finally, the two procedures to calculate the operation speed has compiled, and the example explained the procedure usages, compared and analyzed the computed result.