Abstract: In freeway system, the on-ramp and off-ramp is the link connecting the freeway and ground road, and its also the bottleneck segment which is most prone to traffic congestion. Targeting to evacuate traffic congestion of off-ramp in freeway, a collaborative control model combining off-ramp intersection and downstream intersection under congestion conditions was proposed. The proposed model was divided into two parts: the first was the maximum capacity optimization model in targeted intersection and the second was the maximum vehicle evacuation optimization model in downstream intersection. The first model aimed at improving the capacity of the off-ramp, and the second model aimed to guarantee vehicles from the targeted intersections can drive away as soon as possible after reaching downstream intersections.The results of case studies show that: in aspect of route to evacuate traffic congestion on off-ramp of freeway, the intersection signal timing scheme obtained by the proposed model is 18%, 22.3% and 71.6% better than the single-point signal timing scheme obtained by Webster model in terms of the number of vehicles passing, average delay and average queue length respectively, which significantly improves efficiency of congestion evacuation in off-ramp.

Key words: traffic engineering, urban traffic, freeway off-ramp, congestion evacuation, collaborative control

摘要： 在快速路系统中，出入口匝道是联接快速路与地面道路的纽带，同时也是最易发生拥堵的瓶颈路段。针对快速路出口匝道车辆拥堵问 题，建立拥堵条件下的快速路出口匝道交叉口与下游交叉口协同控制模型，由两个子模型组成，分别是目标交叉口通行能力最大优化模型和 下游交叉口车辆疏散最大优化模型。前者旨在提高出口匝道的通行能力，后者旨在保障目标交叉口方向来车到达下游交叉口后尽快疏散，案 例分析结果表明：在快速路出口匝道拥堵疏解路径中，该模型求得的交叉口信号配时方案比采用Webster配时模型求得的单点信号配时方案 在通过车辆数、车均延误以及平均排队长度方面分别优化了18%、22.3%和71.6%，大大加快了出口匝道拥堵疏解效率。

关键词: 交通工程, 城市交通, 快速路出口匝道, 拥堵疏解, 协同控制