Institute for Transport Studies FACULTY OF THE ENVIRONMENT DTA 2006

Dynamic road traffic assignment models can be used explicitly to represent and analyse route choice and travel times in networks for which the demand for travel varies over time and congestion arises. Static models cannot represent this phenomenon in a satisfactory manner. Despite the long-term research activity and the several approaches that have been introduced, no dominant approach has emerged to dynamic analysis. This seems to be due, at least in part, to the multiplicity of interrelated requirements on dynamic models for them to perform in a satisfactory. Here, we consider analytical approaches to dynamic traffic assignment, and in particular the extent to which they address the issues of realism that arise. This leads to restrictive requirements on traffic models for satisfactory dynamic behaviour. The wider role of assignment modelling is considered in the context of activity analysis, transport planning, and network design. We show how dynamic assignment can be developed together with departure-time choice to serve in these functions. We present these results as a contribution to the literature on dynamic assignment and to support further analysis and model development.