Abstract: The traditional safety analysis model was established at the micro level, which decomposed the adjacent intersections and road sections into two independent research units to study. In dense road network, the distance between intersections of urban arterials was small, and the traffic operation of adjacent sections and intersections affected each other, so it was difficult to divide sections and intersections. Intersection spacing and road network morphology on both sides of the road were important factors affecting the safety of urban arterial. The traditional model studied the road section and intersection accidents respectively, which could not analyze the impact of these two factors on the overall safety of the urban arterial. Based on 21 urban arterials in Shanghai, the adjacent sections and intersections were combined into 118 meso-units according to the road cross-section and traffic operation characteristics, and the road network morphology of the roads on both sides of the meso-units was calculated. Considering the correlation between geometric design and traffic characteristics of meso-units from the same urban arterial, a negative binomial model with random effects was established. The influence of intersection spacing and road network morphology on the safety of urban arterial was analyzed. The results show that compared with irregular grid road network and mixed road network, the number of accidents of urban arterial in grid road network is less; the longer the distance between intersections, the less the accidents on the main road. The meso-level analysis method overcomes the problems of unit division and influencing factor analysis in traditional safety analysis model, and provides suggestions for urban arterial design and road network planning.

Key words: traffic and transportation engineering; urban arterial; traffic safety analysis; meso-level; intersection spacing; road network morphology

摘要： 传统安全分析模型在微观层面建立，将路网中相邻的交叉口和路段分解为两类独立的研究单元分别进行研究。密集路网中城市主干路交叉口间距小，相邻的路段与交叉口交通运行相互影响，难以划分路段与交叉口。交叉口间距和道路两侧路网形态是影响主干路安全的重要因素。传统模型分别针对路段和交叉口事故进行研究，无法分析这两个因素对主干路的整体安全影响。基于上海市21条城市主干路，将相邻路段和交叉口依据道路横断面和交通运行特征组合为118个中观单元，并计算了中观单元两侧道路的路网形态。考虑到来自同一主干路的中观单元几何设计和交通特征互相关联，建立随机效应负二项模型。分析了交叉口间距和路网形态对主干路的安全影响，结果表明：相较于不规则方格路网和混合型路网，位于方格路网中的主干路事故数较少；交叉口间距越长，主干路事故越少。中观分析方法克服了传统安全分析模型中研究单元划分及影响因素分析的问题，为城市主干路设计及路网规划提供了建议。

关键词: 交通运输工程；城市主干路；交通安全分析；中观；交叉口间距；路网形态