HMI-���п���·��ͨӵ�µ�һ��Ԥ��ָ��

借鉴定性推理中描述参数的相关方法，首先提出了描述城市快速路各车道交通流同态程度的概念——同态度量指数（Homogeneous Measure Index ，HMI)，大量对快速路的实证研究得到的HMI指数反应了不同情况下交通流状态的定性差异。通过对北京环路交通拥堵发生与消散过程的观察和分析，本文发现当交通拥堵发生或消散的过程被触发时，不同车道交通流的同态度量指数HMI会发生定性跃迁变化，并且各车道交通流的同态性变化将是一个“同态 非同态同态”的过程，因此可以利用这一性质，将HMI作为一个指标来对城市快速路交通拥堵是否可能发生进行预警。

HMI-Prewarning Index of Traffic Jam Formation on Urban Freeway

In this paper, referring to the concepts of qualitative reasoning, the concepts, such as homogeneous measure index (HMI), are utilized to calculate the cross-lane synchronized degree of the traffic flow. The actual data of Beijing Third Ring Road are presented to describe the procedure of formation of traffic jam, and the concepts proposed in this paper are used to clearly illustrate such procedure. From the empirical data of traffic flow, we find out that for a multi-lane road, before the formation of traffic jam ,the HMI of the traffic flow will change abruptly and the state transition from homogeneous (H-S) to non-homogeneous state (N-S) is likely occur. Therefore, the HMI can be considered as a prewarning index of the formation of traffic jam.