中文摘要：

针对交叉口路段的拥堵特性,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;由该指标确定的拥堵临界点与由交叉口总排队长度所反映的交叉口拥堵形成及消散时刻基本吻合.

英文摘要：

According to the characteristics of traffic jam at intersections and on the basis of qualitative reasoning,a time-related steady-state evaluation index （ SEI） is proposed to describe the traffic situations at the entrance of intersections on urban road. Simulated results indicate that,before the formation of traffic jam at intersections,the SEI of traffic flow abruptly changes and a transition from steady state to unsteady state and finally to steady-state may occur,and that the critical congestion point determined by the SEI basically accords with the formation and dissipation time of traffic jam reflected by the total queue length.