潘弘

       随着城市化进程的加快和机动车保有量的持续快速增长，城市道路交通供需矛盾日益凸显，交通拥挤已经成为全世界所有大中城市面临的主要交通问题。对交通拥挤进行客观合理的度量和评价是正确认识交通拥挤，明确交通拥挤的实际状况，从而深入分析交通拥挤、探讨解决拥挤方法的基础。如何度量和评价交通拥挤呢？目前各国对交通拥挤进行评价的方法和标准不尽相同。国外对交通拥挤的度量和评价这一问题探讨和研究从20世纪50年代就已经开始了，经过五十多年的发展和研究，欧美日等发达国家和地区在拥挤评价领域己经有了非常深入的研究；我国有关交通拥挤度量和评价方面的研究正处于探索阶段，无论在理论上还是实际应用在我国都是新的课题，需要进一步深入研究。

       城市道路及城市道路上的交通组成是城市道路交通拥挤的两个方面：载体和主体的关系。交通拥挤是交通运行的特殊状态，城市道路交通拥挤的特性分析和交通运行评价的基本指标分析是进行交通拥挤评价的两大基础。

       本文首先对城市道路拥挤交通流的特性进行了分析，重点阐述了交通组成是影响交通拥挤严重程度的重要因素；分析了城市道路交通拥挤的成因及拥挤交通流的运行特性；对交通拥挤的定义、分类进行了归纳并对交通拥挤的时空分布特性进行了分析。其次，对交通运行评价的基础指标，如速度、排队长度等进行了基本特性分析及其用于交通拥挤评价时的适用性分析。最后，结合评价目标和用户的需求分析，选择行程时间和排队长度为交通拥挤评价的基础指标，并以此为基础建立面向交通管理者和日常出行者的交通拥挤评价指标体系。

关键词：交通拥挤，基础指标，需求分析，行程时间，排队长度

    With the fastening of the progress of urbanization and the rapid growing of car owning, the gap between supply and demand is becoming bigger and bigger and traffic congestion is becoming a main transportation problem for almost all the big cities of the world. Measuring and estimating congestion objectively and reasonably is the basic for us to see congestion truly, and then we can analyze congestion further and search ideas to solve congestion. How to measure and estimate congestion? Up to now, there is no unified method and standard for congestion measuring and estimating at home and abroad. Some foreign developed countries and district have started the research on congestion measuring from 1950s, and after 50 years of developed, now they have research deeply and got much achievement. For the sake of congestion measuring research, our country is now at the initial stage. No matter on theory or on practice, it is a new subject for us and we have to research deeply.          

    Urban road and the traffic on urban road are the two aspects of traffic congestion: carrier and main body. Traffic congestion is a special state of traffic operation. Traffic congestion property analysis and basic index of traffic operation analysis are the two basics of traffic congestion measuring and estimating.

    Firstly, the characteristics of urban road traffic flow is analyzed, the traffic composition is expounded as a main factor of influencing traffic congestion; the definition and the classification of traffic flow are summed up; the cause of traffic congestion, the operation characteristics of congestion flow, the time and space distribution characteristics of traffic congestion are also analyzed. Secondly, the characteristics and serviceability for traffic congestion measurement of some basic index of traffic operation, such as speed and queue length are analyzed. Thirdly, with estimation target and supply-demand analysis, travel time and queue length are selected as basic index for traffic congestion, subjected to which then a user-oriented index system is set up.

Key Words: traffic congestion, basic index, supply-demand analysis, travel time, queue length