Department of Transportation Engineering, The University of Seoul, 163 Seoulsiripdae-ro Dongdaemun-gu, Seoul, 02504, South Korea.
Accid Anal Prev. 2020 Oct;146:105736. doi: 10.1016/j.aap.2020.105736. Epub 2020 Sep 2.
The consequences of crashes, including injury, loss of lives, and damage to properties, are further worsened when buses plying expressways are involved in the crash. Previous studies have separately analyzed crash severity in terms of monetary cost, injuries and loss of lives, and the size of crashes in terms of the number of vehicles involved. However, as both outcome variables are correlated, it is imperative to perform a combined analysis using an appropriate econometric model to achieve a better model fit. This study contributes to the literature by jointly exploring the factors influencing the severity and size of express bus-involved crashes that occur on expressways and characterizes the dependence between both outcome variables by employing a more plausible copula regression framework. Likelihood ratio tests were also conducted to investigate the temporal stability of the factors that affect both crash severity and size. Based on the goodness-of-fit statistics, the Frank copula model proved superior to the independent ordered probit model. The estimate of the underlying dependence between the outcome variables provided a better comprehension of the correlation between them. Temporal instability was detected for the individual parameters in the models and is attributed to the changing driving behavior due to the heightened road safety campaigns. The results suggest that traffic exposure measures are significantly associated with a higher propensity of observing increased bus crash severity and size. Insights into the factors influencing the size and severity of express bus crashes are discussed, and appropriate engineering, enforcement, and education-related countermeasures are proposed.
当高速公路上行驶的公交车发生碰撞时，碰撞的后果（包括人员受伤、生命损失和财产损失）会进一步恶化。先前的研究分别从货币成本、人员受伤和生命损失以及涉及的车辆数量等方面分析了碰撞的严重程度。然而，由于两个结果变量是相关的，因此使用适当的计量经济学模型进行综合分析以获得更好的模型拟合至关重要。本研究通过联合探索影响高速公路上发生的高速客车碰撞严重程度和规模的因素，为文献做出了贡献，并通过采用更合理的 Copula 回归框架来描述两个结果变量之间的依赖性。还进行了似然比检验，以调查影响碰撞严重程度和规模的因素的时间稳定性。基于拟合优度统计，Frank Copula 模型被证明优于独立有序 Probit 模型。对结果变量之间潜在依赖性的估计提供了对它们之间相关性的更好理解。模型中的各个参数都检测到了时间上的不稳定性，这归因于由于提高道路安全运动而导致的驾驶行为的变化。结果表明，交通暴露量与观察到的更高的公共汽车碰撞严重程度和规模的倾向显著相关。讨论了影响高速客车碰撞规模和严重程度的因素，并提出了适当的工程、执法和教育相关对策。
