Abstract: The crucial factors in measuring and modeling the loading capacity of urban road networks are mainly investigated under the user equilibrium principle. By reviewing the prior literatures, the paper discusses the main drawbacks of the existing methods and models of road network capacity. The four important affecting factors of loading capacity are fully studied, including link capacity, service level requirement, travel demand pattern and route choice behavior. Furthermore，the interrelationship of these factors are discussed. Finally, the zonal reserve capacity, a new measure index to road network capacity, is proposed. By comparing it with reserve capacity, the validity of zonal reserve capacity is further demonstrated.

Key words: network loading capacity, affecting factor, reserve capacity, zonal reserve capacity

摘要： 主要分析均衡配流条件下城市道路网络承载能力度量与建模中的关键性影响因素。通过对以往研究进展进行综述，指出了现有方法和模型存在的不足。结合备用能力度量指标，对路网承载能力建模中的四个重要因素——路段通行能力、服务水平要求、出行需求结构和出行者择路行为进行了深入剖析，并对其内在关联性进行了讨论。最后提出了区域备用能力这一较为系统化的度量指标，并通过比较说明其优越性。

关键词: 路网承载能力, 影响因素, 备用能力, 区域备用能力