Single-vehicle crashes have been shown to differ from two-plus vehicle crashes. Several studies have discussed the issues with modeling single-vehicle and two-plus vehicle crashes together. However, none of the empirical studies have attempted to study two-vehicle (2V) and multiple-vehicle (MV), that is, three-plus crash groups, to understand their correlation and influencing factors. This study first investigated whether there is a need to develop separate safety performance functions for 2V and MV crashes, in addition to single-vehicle crashes. Then, the correlation and influencing factors of 2V and MV were evaluated. Three regression models—a correlated bivariate negative binomial regression (BNR) model, an uncorrelated bivariate negative binomial regression (NR) model, and a univariate negative binomial regression (UNR) model, were developed and compared. The analysis was based on the 2011–2015 crashes that occurred on I-4 in Florida. Findings indicated that the BNR model significantly outperformed the NR and the UNR models. The model results suggest that disaggregating 2V and MV crashes while allowing correlation between the groups for the latent effects in the model best describes the data. Traffic volume, posted speed limit, and median type were found significant in contributing to the occurrence of both 2V and MV crashes. Additional contributing factors for 2V crashes included the presence of interchange influence area, and for MV crashes, the presence of a vertical curve and the presence of a horizontal curve. Study findings could assist transportation officials in implementing specific safety countermeasures for road segments identified as hotspots for 2V and MV crashes.

单车事故已被证明不同于两车以上的事故。几项研究讨论了将单车和两车以上的碰撞一起建模的问题。然而，没有任何实证研究试图研究两车（2V）和多车（MV），即三加碰撞组，以了解它们的相关性和影响因素。本研究首先调查了除了单车碰撞之外，是否需要为 2V 和 MV 碰撞开发单独的安全性能功能。然后，评估了2V和MV的相关性和影响因素。三个回归模型——相关双变量负二项式回归 (BNR) 模型、不相关双变量负二项式回归 (NR) 模型和单变量负二项式回归 (UNR) 模型，进行了开发和比较。该分析基于 2011-2015 年发生在佛罗里达州 I-4 公路上的撞车事故。结果表明，BNR 模型明显优于 NR 和 UNR 模型。模型结果表明，分解 2V 和 MV 崩溃，同时允许模型中潜在影响的组之间的相关性最好地描述了数据。交通量、张贴的限速和中间类型被发现对 2V 和 MV 碰撞的发生有显着影响。2V 碰撞的其他影响因素包括立交影响区的存在，以及 MV 碰撞的垂直曲线和水平曲线的存在。