Abstract: The path of vehicles is one of the important indexes for highway horizontal alignment comfortableness and safety evaluation.The computer simulation technology is adopted to simulate drivers’ track decision behavior in driving in order to study the influence of highway geometric alignment on the path of vehicles under free flow traffic state.For this purpose，the driver directional control model taking highway alignment conditions into consideration is developed on the basis of preview optimal curvature model which is put forward by Academician Guo Konghui with the introduction of SK highway geometric model.The main conclusions obtained are as follows：When the driver’s track decision behavior is influenced only by the condition of the road itself，the path has a tendency to shift inward of the curves as vehicles entered the curves and tended to shift outward of the curves as vehicles exit the curves.The radius of horizontal curve had significant impact on drivers’ track decision behavior，for the larger the radius of curve is，the little the lateral displacement of vehicle path，whereas the greater it would be.

Key words: vehicle path, computer simulation, two-lane highway, horizontal alignment, driving behavior

摘要：

车辆行驶轨迹是道路路线安全性和舒适性评价的重要指标之一。采用计算机仿真技术，模拟驾驶员操纵车辆行驶时的轨迹决策行为，研究在自由流交通状态下，道路几何线形对车辆行驶轨迹的影响规律。为此，在郭孔辉院士提出的预瞄最优曲率模型的基础上，引入了SK道路几何模型，建立了实际道路条件输入的驾驶员方向控制模型。得到以下主要研究结论：当驾驶员轨迹决策行为只受道路本身条件影响时，且车辆在进入曲线段时，行驶轨迹存在着朝曲线内侧偏移的运动趋势;在出曲线段时，车辆行驶轨迹趋向朝曲线外侧偏移。平曲线半径大小对驾驶员轨迹决策行为有着显著的影响，圆曲线半径越大，行车轨迹侧向偏移量越小，反之越大。

关键词: 车辆行驶轨迹, 计算机仿真, 双车道公路, 平面线形, 驾驶行为