ABSTRACT There is a need to validate the results of conflict-based before-after (BA) evaluations in terms of their collision reduction estimation. This study compares the results of a collision-based and a conflict-based BA safety evaluation of left-turn bay extension. Both collision and conflict data were collected and used in the evaluation. The collision-based BA evaluation was conducted by developing a Poisson–Lognormal intervention (PLNI) model which was estimated by the full Bayesian approach. The conflict-based BA analysis was performed by an extreme value theory (EVT) model developed with the generalized extreme value (GEV) distribution. The comparison showed consistent results from the two approaches. The results showed a reduction of 56.2% in actual collisions from the PLNI model and a reduction of 63.9% in estimated collisions from the EVT model. These results provide support for the validity and reliability of using traffic conflicts in BA studies.

中文翻译：

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基于碰撞和基于冲突的左转车位扩展安全评价比较

摘要 有必要验证基于冲突的前后 (​​BA) 评估在减少碰撞估计方面的结果。本研究比较了基于碰撞和基于冲突的左转湾扩展的 BA 安全评估结果。碰撞和冲突数据都被收集并用于评估。基于碰撞的 BA 评估是通过开发泊松-对数正态干预 (PLNI) 模型进行的，该模型由完整的贝叶斯方法估计。基于冲突的 BA 分析是通过使用广义极值 (GEV) 分布开发的极值理论 (EVT) 模型进行的。比较显示两种方法的结果一致。结果表明，与 PLNI 模型相比，实际碰撞减少了 56.2%，减少了 63%。根据 EVT 模型估计的碰撞率为 9%。这些结果为在 BA 研究中使用交通冲突的有效性和可靠性提供了支持。