Research On The Limit Length Of Separate Section’s Expressway Slope

Since the reform and opening up, China’s road transport industry has reached the level of developed countries with only twenty to thirty years. Moreover, after 30 to 40 years of developing, it has achieved leapfrog development phase. But there are still some serious imbalanced problems in this industry. Due to restrictions, development of terrain conditions of the western mountains are far behind the eastern coastal areas. Vigorously constructing the transport infrastructure is still the primary task in further promoting the great western development strategy. What is more, the construction of the highway network encryption is of imminence. In the mountainous western part of the terrain, especially the complex sections, if integrated cross-section is still been used, it is bound to cause a large fill big dig, to destroy the environment, or even to reduce linear index when constructing the highway. In response to this phenomenon, the terrain of the separate section came into being. Using separate section not only conforms to the terrain to reduce construction costs and protect the environment, but also can improve the alignment indicators highway. At present, when the construction of the separated section encountered longitudinal slop, because of the vague standard of limiting the maximum value about slope length, it is usually unreasonable to adopt the value of integral cross-section directly. Therefore, it is more in line with actual driving conditions of the car to study on separated section grew longitudinal slope length limit, uphill and downhill circumstances separately.This paper, the date based on the expressway of Xian to Shangzhou, selects Dongfeng EQ5208XXY2 type van truck for test models of dynamic performance and braking performance of the car through the investigation and analysis. According to the test to the car’s dynamic performance, the largest longitudinal is investigated. It studies from three aspects, that is, whether considering the impact of wind speed on the uphill from the car, whether the driver shifting slope length limit and the speed of the car on the top of the hill. Then it revises the uphill limited value length accordingly. Finally, the value of the slope length restriction is determined. The paper studies the largest longitudinal of the value of unlimited length downhill, according to the brake performance of test vehicles, establishes brake drum temperature model, depending on the temperature of the brake drum, and studies the limits of downhill slope length. In the end, according to the results of the study presented, it puts forward the slope length limit highway separated section uphill and downhill sections.