The discretionary lane-changing behavior is highly associated with crash occurrence. This paper investigates the dynamic tradeoff between safety and efficiency and influencing factors of the decision-making process for the discretionary lane-change. A random parameters logit approach with heterogeneity in means and variances is employed on a microscopic vehicle trajectory dataset. Four vehicles are analyzed as a discretionary lane-changing group, and both the distance-related and speed-related factors are taken into account to examine their dynamic effects. The modeling results indicate that (1) two distance-related variables produce significant random parameters with heterogeneity in means and variances, while there is only one speed-related variable having significant result for heterogeneity in means and variances; (2) the relationship between the speed of lane-changing vehicle and the heterogeneity in mean of vehicle clearance distance between leading vehicle in current lane and lane-changing vehicle quantitatively demonstrates that when the driver decides whether to change lanes, the driver considers the tradeoff between distance (i.e., safety) and speed (i.e., efficiency) at the same time; and (3) the number of significant variables is gradually decreased during the lane-changing decision-making process. It demonstrates that the lane-changing decision is a dynamic process where drivers gradually select more critical factors and pay more attention to them.

随意改变车道的行为与发生碰撞高度相关。本文研究了安全性和效率之间的动态权衡，以及自由行车道变更决策过程的影响因素。在微观车辆轨迹数据集上采用均值和方差均异的随机参数对数方法。分析了四辆车作为可随意改变车道的组，并考虑了距离相关和速度相关的因素，以检查它们的动态影响。建模结果表明：（1）两个距离相关的变量产生均值和方差异质性显着的随机参数，而只有一个速度相关的变量均值和方差异质性显着的结果；（2）变道车辆的速度与当前车道中领先车辆与变道车辆之间的车辆间隙平均距离的异质性之间的关系定量地表明，当驾驶员决定是否改变车道时，驾驶员会考虑权衡同时在距离（即安全）和速度（即效率）之间；（3）在变道决策过程中，显着变量的数量逐渐减少。这表明换道决策是一个动态过程，驾驶员逐渐选择更多关键因素并给予更多关注。