School of Sustainable Engineering and the Built Environment, Arizona State University, PO Box 875306, Tempe, AZ 85281, USA.
Accid Anal Prev. 2010 Mar;42(2):626-36. doi: 10.1016/j.aap.2009.10.009. Epub 2009 Nov 7.
Traffic oscillations are typical features of congested traffic flow that are characterized by recurring decelerations followed by accelerations (stop-and-go driving). The negative environmental impacts of these oscillations are widely accepted, but their impact on traffic safety has been debated. This paper describes the impact of freeway traffic oscillations on traffic safety. This study employs a matched case-control design using high-resolution traffic and crash data from a freeway segment. Traffic conditions prior to each crash were taken as cases, while traffic conditions during the same periods on days without crashes were taken as controls. These were also matched by presence of congestion, geometry and weather. A total of 82 cases and about 80,000 candidate controls were extracted from more than three years of data from 2004 to 2007. Conditional logistic regression models were developed based on the case-control samples. To verify consistency in the results, 20 different sets of controls were randomly extracted from the candidate pool for varying control-case ratios. The results reveal that the standard deviation of speed (thus, oscillations) is a significant variable, with an average odds ratio of about 1.08. This implies that the likelihood of a (rear-end) crash increases by about 8% with an additional unit increase in the standard deviation of speed. The average traffic states prior to crashes were less significant than the speed variations in congestion.
交通振荡是交通拥堵流的典型特征，其特点是反复减速后加速（停停走走驾驶）。人们普遍接受这些振荡对环境的负面影响，但对其对交通安全的影响一直存在争议。本文描述了高速公路交通振荡对交通安全的影响。本研究采用了一种匹配病例对照设计，使用了来自一段高速公路的高分辨率交通和碰撞数据。将每次碰撞前的交通状况作为病例，而在没有碰撞的同一天的同一时期的交通状况作为对照。这些病例和对照还通过存在拥堵、几何形状和天气进行了匹配。从 2004 年到 2007 年的三年多数据中提取了 82 个病例和大约 80000 个候选对照。基于病例对照样本开发了条件逻辑回归模型。为了验证结果的一致性，从候选池中随机提取了 20 组不同的对照，用于不同的对照-病例比。结果表明，速度的标准差（因此是振荡）是一个重要的变量，平均优势比约为 1.08。这意味着，随着速度标准差的增加一个单位，（追尾）碰撞的可能性增加约 8%。碰撞前的平均交通状态不如拥堵中的速度变化显著。
