Effect of traffic density on drivers’ lane change and overtaking maneuvers in freeway situation—A driving simulator–based study

<b>Objective:</b> The aim of this study is to examine the effect of traffic density on drivers’ lane change and overtaking maneuvers. The differences between drivers’ left and right lane changing/overtaking maneuvers were also investigated. <b>Method:</b> A driving simulator experiment was conducted and 24 participants took part in this experiment. Based on the driving simulation data, lane change frequency, time duration, average speed, and acceleration were extracted as key variables of lane change maneuvers; overtaking frequency, overtaking duration, initial overtaking distance and headway, instantaneous speed, and acceleration before overtaking were analyzed as the key overtaking variables. One-way repeated measures analysis of variance (ANOVA), the Friedman test, and the Wilcoxon signed rank test were adopted for hypothesis tests with a significance level of .05. Further pairwise comparisons were performed with a Bonferroni correction for multiple comparisons. <b>Results:</b> Some significant differences in lane change and overtake behaviors were observed among different traffic densities: (1) both lane change and overtaking frequencies significantly increase with traffic density; (2) the average lane change acceleration and instantaneous overtaking acceleration significantly increase with traffic density; (3) as the traffic density increases, the initial overtaking distance and headway decrease. As for the effect of the directions of maneuvers, the (1) time duration of lane change and overtaking from the right side was significantly shorter than that from the left side; (2) right initial overtaking distance/headway was smaller than that of the left side; (3) right instantaneous overtaking acceleration was significantly higher than the left instantaneous acceleration. <b>Conclusions:</b> The results showed that as traffic density increases, drivers’ lane changing and overtaking intentions are enhanced. Both initial overtaking distance and headway decrease with traffic density, which might influence road safety. In addition, drivers do not show a preference on the directions of lane change or overtaking according to frequency. However, drivers tend to be more decisive and reckless when overtaking on the right because of a smaller distance/headway before overtaking, higher instantaneous acceleration, and a more restricted field of view compared with overtaking on the left.

研究目标：本研究旨在探究交通密度对驾驶员变道与超车操作行为的影响，并同时考察驾驶员左右两侧变道/超车操作行为之间的差异。
研究方法：本研究开展了驾驶模拟器实验，共有24名受试者参与实验。基于驾驶仿真数据，本研究提取变道频率、变道时长、平均车速与加速度作为变道操作的核心变量；针对超车操作，则分析了超车频率、超车时长、初始超车距离与跟车时距、超车前瞬时车速与加速度作为核心超车变量。本研究采用单因素重复测量方差分析（Analysis of Variance，ANOVA）、弗里德曼检验（Friedman Test）以及威尔科克森符号秩检验（Wilcoxon Signed Rank Test）进行假设检验，显著性水平设定为0.05；并通过邦费罗尼校正（Bonferroni Correction）进行多重比较的事后两两检验。
研究结果：不同交通密度条件下，驾驶员的变道与超车行为存在显著差异：（1）变道与超车频率均随交通密度升高而显著提升；（2）平均变道加速度与超车瞬时加速度均随交通密度升高而显著增大；（3）随着交通密度增加，初始超车距离与跟车时距均有所减小。就操作方向的影响而言：（1）右侧变道与超车的时长显著短于左侧；（2）右侧初始超车距离/跟车时距小于左侧；（3）右侧超车瞬时加速度显著高于左侧。
研究结论：结果表明，随着交通密度提升，驾驶员的变道与超车意图愈发强烈。初始超车距离与跟车时距随交通密度升高而减小，这可能会对道路交通安全产生影响。此外，从变道与超车的频率来看，驾驶员并未表现出单侧方向偏好。但相较于左侧超车，右侧超车时由于超车前的距离/跟车时距更短、瞬时加速度更高，且视野受限更为明显，驾驶员往往会表现得更为果断甚至鲁莽。