應用存活模式探討高速公路交通事故處理時間變異性及偏態性

Exploring Freeway Traffic Accident Duration Variance and Skewness by the Survival Model of Probability Distribution Parameterization

為探討國道事故處理時間對交通影響，本文以108 年高速公路 12,894 筆交通事故與持續時間資料，分配建立可將位置參數 (location parameter)、尺度參數(scale parameter) 及狀態參數 (shape parameter) 等廣義對數伽瑪存活機率分配參數化模型，分析相關影響變數及詮釋結果。結果顯示分配參數化廣義對數伽瑪模式 (P-GLG) 有較佳績效，並指出交通事故倘為高嚴重性、涉及大型重型載重車（貨櫃車及大貨車），邊坡事故、肇事型態為起火冒煙、車輛翻覆等特性，而有較長事故處理時間及高變異性。推估108 年事故處理時間涉及A1 類事故平均時間最長，至少需42 分鐘；A2 事故約至少半小時；A3 事故多數於15 分鐘內處理。另涉入大型車至少需增加20 分鐘。本研究歸納影響國道事故處理時間之因素及變異，以協助預判事故對國道影響。

To explore the effects of freeway traffic accident duration on freeway traffic, the study combined both freeway accident and duration data sets from the Taiwan national highway police and freeway administration sources. We selected 12,894 accident records for year 2019, and established Generalized Log-Gamma (GLG) survival models with constant parameters, and a Generalized Log-Gamma survival model with probability distribution parameterization (P-GLG) to analyze freeway traffic accident duration. Unlike similar GLG survival models, the advantage of the P-GLG model is its location parameter, scale parameter and shape parameter of underlying distribution, which is formulated with covariates. The results show the superiority of the P-GLG model to other GLG models. The variables considered in the established models indicate high averages of traffic accident duration for severe crashes and those involving large freight vehicles. The situation is worse for crashes located at a side slope, rollover crashes and fire/smoke traffic accident involved. The referred risk factors have high accident duration averages and cause high variance, which are difficult to determine the accident clearance duration. Additionally, the estimates of the accident duration for year 2019 point out the averages of A1 level crash is at least 42 minutes, the A2 level crash is 30 minutes, and the A3 level is within 15 minutes. The average of involving heavy freight vehicles is more than 20 minutes. The study contributes to determine the national highway traffic accident duration, and provide precautions for national highway traffic freeway accident.