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混合交通现象是我国城市交叉口最为显著的交通特点之一. 本文分析了城市信号交叉口的行人自行车绿灯放行特性，提出了绿灯放行两阶段的定义：第一阶段为行人自行车以聚集群的形式通过；第二个阶段为行人自行车以随机单体的形式通过. 分析了第一阶段聚集群在通行过程的内部结构变化；提出了人行横道“虚拟网格”方法，建立了聚集群空间占有率模型，分析了放行过程聚集群空间占有率的变化. 最后通过实例，基于视频分析的方法，通过对信号交叉口行人自行车时空位移曲线图的分析，可以发现绿灯放行的前8秒为第一阶段，之后为第二阶段；由于速度差异，放行过程中自行车会逐渐超越行人到达聚集的前段. 应用聚集群空间占有率模型，发现绿灯放行过程空间占有率先增加后减小.

Releasing Characteristics of Pedestrians and Bicycles in Urban Signalized Intersection of Green Time

Mixed traffic is one of the most remarkable transportation characteristics in Chinese cities. With extensive research on the releasing characteristics, the paper presents a definition of the two-stage of the releasing characteristic. The first stage is that the pedestrians and bicycles enter the crosswalk in the form of conglomeration; the second stage is that the pedestrians and bicycles enter the crosswalks stochastically. The variation of the inner structure of the conglomeration in the first stage of green time is analyzed, and a method of "suppositional grids" is presented to describe the conglomeration. The model of space occupation ratio is developed to describe the dynamic movement of conglomeration. Then, the characteristics of the pedestrians and bicycles are illustrated by a field study. A time-space chart of the pedestrians and bicycles is extracted. It can be found the curve is dense before the 8th second of the green time, which is considered ss the first stage of the releasing time, and the following green time is regarded as the second stage. Because of differences of the velocities, the bicycles usually surpass the pedestrians to get the front of the conglomeration. Based on the model of space occupation ratio, the space occupation ratio of the conglomeration is observed to increase first and decrease then.