山岭区高速公路坡长限制研究

Research on the Limitation of Grade Length on Freeways in Mountain Area

探讨山岭区高速公路纵坡坡长限制的确定方法.以我国高等级公路上行驶的典型车型(EQ140)为研究对象,通过对3条正在运营的山岭区高速公路7个断面运行车速的调查、分析,建立了车辆第15%位车速与道路纵坡坡度之间的关系模型;以车辆的第15%位车速、第85%位车速为速度限制条件,提出了依据道路纵坡坡度值大小来确定容许车速的方法;利用汽车行驶理论,分析了车辆在纵坡上的减速距离;以分析结果为基础,提出了我国公路路线设计规范适当放宽坡长限制的建议,同时给出了山岭区高速公路纵坡坡长限制的修改建议值,以供设计人员在山岭区高速公路路线设计时参考.

A method to determine the limitation of grade length un freeways in mountain area was presented in this paper. The relationship models between 15^th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Used 15^th percentile speeds and 85^th percentile speeds as speed limitation, the method of determining admitted velocities was put forward according to the grades. Deceleration distance of longitudinal slopway was analyzed based on the theories of vehicle. According to the results of analysis, the limitation of grade length was loosed and the maximum grade of design specification for highway was enlarged. Finally, the values of limitation of grade length on freeway were put forward. The results could be used as references for highway designed.