为分析高速公路线形空间参数对交通安全的影响，对美国华盛顿州5条州际高速公路的线形数据和公路上2011年至2018年发生的事故数据进行收集和统计处理，以百米为定长将公路进行分段，并计算出各路段的平均空间曲率、与前相邻路段曲率差绝对值、与后相邻路段曲率差绝对值作为描述变量，路段事故频数作为被描述变量，分别采用传统负二项模型、零膨胀负二项模型、零截尾负二项模型对全部路段数据和发生事故的路段数据进行拟合分析。结果表明：基于全部路段数据的模型中负二项模型优于零膨胀负二项模型；基于发生事故的路段数据的模型中，零截尾负二项模型优于负二项模型；在4个模型中，路段的安全水平和该路段与前、后相邻路段曲率差绝对值之间均存在较大的正关联，即增加公路三维曲率的连续性能提高交通安全性水平。由此可见，与前、后相邻路段曲率差绝对值可以作为道路线形水平评价指标，为道路线形设计的优化提供支持。

In order to analyze the impact of freeway three-dimensional spatial alignment continuity decline on traffic safety, this paper collected and statistically processed the alignment data and accident data of five interstate freeways in Washington State, USA from 2011 to 2018. The freeways were segmented with 100 meters length as the fixed length unit. The average spatial curvature of each unit (ASC), the absolute value of the curvature difference with the previous adjacent freeway unit(AVDP), and the absolute value of the curvature difference with the next adjacent freeway unit(AVDN) were calculated as descriptive variables, and the number of freeway unit accidents was used as the described variable. The traditional negative binomial model, zero-inflated negative binomial model, and zero-truncated negative binomial model were used to perform fitting analysis on all freeway units data and the freeway units data where accidents occurred. The results show that: the negative binomial model fits better than the zero-inflated negative binomial model based on all units data; the zero-truncated negative binomial model fits better than the negative binomial model based on the accident-occurring units data. In the four models, there is a large positive correlation between the absolute value of the curvature difference of the adjacent freeway unit and the safety level of the freeway unit, that is, increasing the continuous performance of the three-dimensional curvature of the freeway can improve the traffic safety level. It indicates that AVDP and AVDN can be used as a freeway alignment level evaluation index to provide support for the optimization of freeway alignment design.