ABSTRACT
Road space is a scarce resource, and traffic engineers need to ensure that roads are able to accommodate as much traffic as possible, subject to safety and environmental constraints. In other words, we need to maximise the capacity of the road. But how is capacity measured, and what influences it? These questions lie at the core of traffic flow theory, a science which has attracted both theoretical and empirical analysis. In this chapter there is space only to introduce the concepts, the principal parameters and some relationships which enable us to estimate capacity. Further developments of these concepts are given in reference 1.
