交通事故导致的高速公路拥堵状态判别方法

为量化分析不同交通事故条件下的高速公路路段拥堵情况，研究路段偶发性拥堵规律，本文构建了1个基于行程时间可靠性指标的高速公路路段拥堵判别方法。建立基于美国《公路通行能力手册》中行程时间可靠性分析方法的路段行程时间可靠性模型，并采用西南某高速公路路段实际数据校准模型。利用蒙特卡洛模拟方法生成交通事故场景，将交通事故解构为交通事故发生位置、交通事故严重程度、交通事故持续时间、交通事故发生频率4个特征，并以行程时间指数为路段拥堵量化指标，研究不同交通事故特征水平下的高速公路路段拥堵规律，并判别路段拥堵程度。研究结果表明:美国《公路通行能力手册》的行程时间可靠性分析方法具有可移植性，校准后可应用于国内高速公路路段；交通量接近饱和时，交通事故发生在出口匝道段的拥堵程度高于基本路段与入口匝道段，单车道关闭场景下的交通事故影响远高于路肩关闭场景下的交通事故；交通量接近自由流状态时，拥堵程度对严重程度不敏感；任何交通量水平下，单车道关闭场景下的交通事故持续时间一旦超过15 min，路段拥堵程度极有可能剧增。本文构建的路段拥堵判别方法，可以在精细化探究偶发性交通事故拥堵规律的同时划分路段拥堵等级，为相关部门的事故管理提供理论支撑。 

A Method for Identifying Traffic Congestion Resulting from Accidents on Freeways

Based on the reliability of travel time, a method for identifying traffic congestion resulting from accidents is proposed, in order to quantitatively study how random congestion takes place on freeway sections and how congestion evolves under various traffic accidents. A model based on the method for studying the reliability of travel-time outlined in the Highway Capacity Manual is developed, which is calibrated based on observed data from a section of a freeway in Southwest China. A Monte Carlo simulation method is adopted to simulate various traffic accident scenarios. These traffic accidents are featured by four characteristics: location, severity, duration, and frequency. The mechanism that traffic congestion takes place and evolves is investigated and travel time index is used to represent the level of congestion on freeway sections under different traffic accidents. Study results show that ①The method presented in the Highway Capacity Manual is portable. ②When traffic volume is closed to saturation, the impact of traffic accidents taking place at the off-ramp sections is higher than those occur in the basic and on-ramp sections, and their impact is much higher under the single-lane closure scenario than that under the shoulder-closure scenario. ③When the traffic flow is close to free flow, the congestion is not sensitive to the accident severity. ④ Congestion would increase dramatically under the single-lane closure scenario when the accident lasts for more than 15 minutes at any traffic volume level. The proposed method for identifying traffic congestion can contribute to detailed exploration of the congestion patterns resulting from traffic accidents as well as classification of the congestion of freeway sections, which shall provide theoretical support to the accident management of relevant highway and transportation departments.