Abstract: Distracted driving has become a major contributing factor to traffic accidents. To investigate the temporal instability and unobserved heterogeneity of the factors influencing the severity of distracted driving accidents, the partial time constraint method was employed to address temporally unstable parameters and a random parameter Logit model that accounted for both mean and variance heterogeneity was developed. Thirty-seven potential influencing factors were extracted from aspects such as driver, road, vehicle and environment. Taking the severity of three categories of accidents as the dependent variables, multiple comparisons of log-likelihood values were conducted by capturing variations in the means and variances of the random parameters. The temporal instability of different influencing factors was verified, and the causal mechanisms of accident severity based on marginal effects were analyzed. The results show that distracted driving accidents exhibit significant temporal instability. “Male gender, collision with fixed objects, and wet road surfaces” have random effects during 2017-2019; their means are significantly associated with variables such as SUVs, not wearing a seat belt and the elderly, and their variances are influenced by male gender and wet road surfaces. Factors including not wearing a seat belt, rollover accidents, trucks, and speed limits above 60 km/h significantly increase accident severity. The research results provide certain valuable references for improving traffic safety regulations and preventing driving accidents.

Key words: traffic engineering; distracted driving accidents; random parameter Logit model considering mean and variance heterogeneity; temporal instability analysis; partial constraint theory

摘要： 分心驾驶已成为引发交通事故的重要因素，为探究分心驾驶事故严重程度影响因素的时间不稳定性和未观测到的异质性，利用部分时间约束方法处理时间不稳定性参数，建立考虑均值和方差异质性的随机参数Logit模型；从驾驶员、道路、车辆和环境等方面提取37个潜在影响因素，以3类事故严重程度为因变量，通过捕捉随机参数均值和方差的变化情况，进行多组对数似然值比较，验证不同影响因素的时间不稳定特性，并基于边际效应开展事故严重度致因机理分析。结果表明：分心驾驶事故存在显著的时间不稳定性；“男性、碰撞固定物体、湿滑路面”等因素在2017—2019年中具有随机效应，其均值与“SUV、未系安全带、老年”等因素显著相关，方差受“男性和湿滑路面”因素影响；“未系安全带、翻车、货车、限速大于等于60 km/h”等因素显著增加了事故严重程度。研究成果对完善交通安全法规和预防驾驶事故具有一定参考价值。

关键词: 交通工程；分心驾驶事故；考虑均值和方差异质性的随机参数Logit模型；时间不稳定性分析；部分约束理论