Fundamental diagram of traffic flows on urban roads – local versus whole-link approaches

Abstract

Fundamental diagrams of traffic flow variables have been quite useful in determining freeway operations quality. However, they are usually not used for that purpose on urban roads. This work is an approach towards utilizing the fundamental diagram on urban roads, too. Based on a host of empirical as well as simulation work, the first steps towards a routine application of the fundamental diagram are sketched. In addition, two approaches are compared, one that uses a traditional fundamental diagram as measured by loop detectors, and the second one which uses a whole-link approach relating link-travel-speed with volume. Especially the travel times contain important information that can be used for traffic management applications.