國道高速公路交通事故持續時間分析與推估：脆弱性存活模型之應用

Investigating and Estimating the Duration of Traffic Accidents on Taiwanese Highways: An Application of Frailty Survival Models

交通事故持續時間是造成車流延滯及二次事故的重要因素，本研究蒐集國內高速公路共4,074筆交通事故與持續時間資料，建構存活分析之加速失效模式解析事故特性、道路及環境特性以及事故時空特性等三大類變數與交通事故持續時間的關係。研究結果顯示，以逆高斯脆弱對數羅吉斯特之加速失效模式最能捕捉國內高速公路交通事故所引發之事故持續時間之非單調特性，有別於國外文獻之單調韋伯校估結果。分析結果亦顯示事故傷亡愈嚴重、事故牽涉車輛數愈多、牽涉大型車輛、起火、翻車以及非追撞事故皆顯著與事故持續時間的增加有關，而發生在晨峰、夜間以及國道高速公路南部路段之事故持續時間也顯著較長。

Incident duration is one of the primary causes leading to traffic delay and secondary accidents. This study demonstrates an effort of collecting and fusing accident and duration data sets from various sources in Taiwan. We developed Accelerated Failure Time (AFT) models based on 4,074 records. The relationship between incident duration and three sets of explanatory variables - accident characteristics, road and environmental features, and spatial and temporal characteristics of accidents were investigated. The results show that the AFT model with a log-logistic distribution and inverse Gaussian-distributed frailty is the best fitted model, which implies the non-monotonic feature of incident duration in Taiwan and is different from the usually-seen monotonic Weibull model in the literature. The results also suggest further incident duration with the increase of accident severity and the number of involved vehicles, the involvement of large vehicles, fire accidents, rollover accidents and non-rear-end accidents. Significantly longer duration is also found during peak periods, nighttime, and the freeway segments in southern Taiwan. The analysis results could be considered as a preliminary study of incident duration in Taiwan. It could be used as a reference for estimating external cost due to traffic accidents and for the allocation of emergency response resources.