快速道路匝道影响区交通事故风险影响机理与安全优化设计

The influence areas of freeway ramps, including merging, diverging, and weaving areas, are crash prone locations on freeways. The focus of the proposed project is on the contributing factors and safety design of the influence areas of freeway ramps. More specifically, the proposed project will study the following research tasks: (1) to study the crash precursors of crashes at the influence areas of freeway ramps based on dynamic traffic flow data. With such information, methods will be developed to divide traffic flow into different traffic safety states, and a procedure will also be developed for identifying the hazardous traffic states at the influence areas of freeway ramps; (2) to identify the mechanism of the occurrence and evolution of hazardous traffic flow states at the influence areas of freeway ramps, and to explore the multi-level contributing factors of the hazardous traffic flow states; (3) to develop real-time crash risks models based on different traffic states to establish a relationship between the crash risks, the roadway design characteristics, the behavioral characteristics of drivers, and the traffic flow states. Particular attention will be given to understand to what extent the roadway design factors affect crash risks; and (4) to identify systematically how the key geometric design characteristics, such as the length of weaving areas, the length of acceleration and deceleration lanes, the widening of ramp entrances and exits, and the lane configurations, affect traffic safety states and crash risks at the influence areas of freeway ramps. Methods will also be proposed to optimize the key geometric design characteristics of the influence areas of freeway ramps such that crash risks can be minimized. Based on the research results, methods and guidelines will be developed to help traffic engineers make design decisions to improve the safety performance of freeway ramps.

快速道路匝道影响区包括分流区、合流区和交织区，是快速道路交通安全的主要瓶颈。项目拟针对快速道路匝道影响区交通事故风险影响机理与安全优化设计展开研究。基于动态交通流数据研究匝道影响区交通事故前兆特征，提出安全导向的交通流状态分类方法和危险交通流状态的判别方法；归纳匝道影响区危险交通流状态发生和演化规律，解析危险交通流状态时空演化的分层致因；构建基于交通安全状态的交通事故风险模型，解析匝道影响区道路设计因素对交通事故风险的影响机理，建立道路设计-驾驶人行为-交通流状态-交通事故风险的关联机制；系统解析交织区长度、加减速车道长度、出入口拓宽形式、车道平衡方式等关键交通组织设计参数对交通安全状态和交通事故风险的影响，建立匝道影响区交通组织设计多参数协同优化方法，在研究基础上形成有效支撑快速道路匝道影响区道路安全优化设计的理论、方法、指南，为保障快速道路安全、高效运行提供科学支撑。

快速道路匝道影响区包括分流区、合流区和交织区，是快速道路交通安全的主要瓶颈。项目拟针对快速道路匝道影响区交通事故风险影响机理与安全优化设计展开研究。通过调研美国国15条快速道路86个影响区和中国南20条快速道路100个匝道影响区交通组织设计、交通流和事故数据，归纳了快速道路匝道影响区类型和设计参数；建立了快速道路匝道影响区事故形态与设计参数（交织区类型、出口匝道车道数、辅助车道数、中央分隔带宽度、路肩宽度、出入口匝道间距、分道角区、限速值）的关联关系；基于车辆轨迹数据解析了快速道路匝道影响区交通流运行特征，分析了道路设计对驾驶行为（车头时距、换道行为、换道位置、换道间距）和交通流（速度、合流比、分流比、匝道流量比）的影响；构建了卷积自编码深度聚类算法的交通流状态分类方法和危险交通流状态的判别模型，解析了危险交通流状态时空演化的分层致因；建立了快速道路匝道影响区交通设计影响机理；提出了快速道路匝道影响区交通组织设计安全优化分析方法，基于交通事故风险模型绘制快速道路匝道影响区交通设计参数设置标准曲线，提出安全导向的交织区关键交通组织设计要素（交织区类型、主路基本车道数、匝道短间距）选择流程。