高速公路直线段最大长度合理取值研究

从车辆运行状态的角度出发,将直线段上车辆的运行分为加速行驶、匀速行驶和减速行驶3个过程,分析了车辆在不同行驶过程中的行驶时间与行驶距离,以直线段上最长行驶时间70 s作为最大直线段长度的控制条件,推导了基于运行车速的高速公路直线段最大长度计算模型。模型表明设计速度为120 km/h的高速公路直线段最大长度要比20倍设计速度小,而其他设计速度的高速公路则要视直线段相邻曲线起终点的运行车速而定。以现场实测数据为依据,建立了高速公路平曲线起终点小型车运行车速与平曲线半径的回归模型,并给出了计算实例。基于运行车速确定高速公路直线段最大长度能够较好地满足驾驶员的实际需求,提出的计算模型可为高速公路设计及安全审计提供依据。

Study on Reasonable Value of the Largest Length of Straight Line Section on Freeway

From the viewpoint of vehicle's operation state,vehicle's running on straight line section of freeway is divided into three courses,i.e.,accelerating course,even-speed course and decelerating course.Running time and distance in the three courses were analyzed.Taking the largest length of straight line section on which the running time is no more than seventy seconds as the control condition,the largest length of straight line section calculation model based on operation speed of freeway was presented.The model shows that the largest length of straight line section at speed of 120 km/h is less than that at twenty multiples of design speed on freeway and it needs to be determined by operation speed of start point and end point of adjacent curve for freeways with other design speed.Based on survey data,the regression model between operation speed of car and plane curve radius of freeway was established and the calculation example was presented.The largest length of straight line section of freeway determined by operation speed can meet driver's demand better,and its calculation model can provide gist for freeway design and safety audit.