Application of a simulation-based dynamic traffic assignment model

The evaluation of on-line intelligent transportation system (ITS) measures, such as adaptive route-guidance and traffic management systems, depend heavily on the use of faster than real time traffic simulation models. Fast-running traffic models are needed off-line for use in iterative approaches that imitate drivers´ adaptation to changes to the network topology. The paper describes a simulation-based dynamic-equilibrium traffic assignment model. The determination of time-dependent path flows is modeled as a master problem that is solved using the method of successive averages (MSA). The determination of path travel times for a given set of path flows is the network-loading sub-problem, which is solved using the space-time queueing approach of Mahut (2000). This loading method has been shown to provide reasonably accurate results with very little computational effort. The model was applied to the Stockholm road network, which consists of 4342 links, 1980 nodes and 250 zones, representing over 11,000 turns. The results show that this model is applicable to medium-size networks with a very reasonable computation time.