This paper discusses various aspects of area capacity analysis and various approaches to it. It is quite complex to establish road capacity, because: (1) capacity is not well-defined, even for a specific intersection or segment of road; and (2) the relationship between traffic volume and capacity varies greatly over a road network. Answering the areawide capacity question makes it easier to construct a framework, within which politicians and civil servants can work, which offers precise, quantifiable measures modified by good judgement and local desires. Specific examples show that setting capacity in terms of a single `failure' or total `failure' will not produce results that can be used well by land-planning can be used well by land-planning decision makers. Traffic conditions must be combined with political, social and economic considerations to establish a proper threshold for development. With known information about traffic volumes and the road network, a composite volume/capacity ratio has some potential for measuring areawide capacity, despite some defects. However, it may be more appropriate to judge areawide capacity through more than one measure, but this latter approach has difficulties if significant parts of the study area are already above capacity.
Abstract