城市道路交通平面交叉路口拥堵预测

针对交叉口路段拥堵特性，基于定性推理的相关方法，从时间的角度，提出了描述城市交叉口进口路段运行状况的评价指标——稳态评判指数。仿真实验表明，当交叉口交通拥堵与消散的过程被触发时，稳态评判指数会发生定性跃迁，并且每个高峰期的到来都会经历一个“稳态——非稳态——稳态”的过程；并且由该指数确定的拥堵临界点时刻与由交叉口总排队长度所反映的交叉口拥堵形成与消散时刻基本吻合，为交叉口的运行状况评价及拥堵预警提供一个指标。

Pre-warning index of traffic jam formation at intersections on urban road

The traffic jams at intersection road was studied. Based on the qualitative reasoning, steady-state evaluation index (SEI) was utilized to calculate the station of urban road. From the empirical data of traffic flow，we find out that for multi-time，before the formation of traffic jam at intersection，the SEI of the traffic flow will change abruptly and the state transition from steady-state (S-N) to non-steady-state (N-S) is likely occur．Furthermore，the congestion critical point at intersection caused by SEI and the congestion state reflected by the total queue length are in good agreement. Therefore, SEI can be considered as a pre-warning index of the formation of traffic jam for intersections.