Evaluation of a simulation-based dynamic traffic assignment model in off-line use

ITS technologies that provide information to drivers can be an effective means of using the existing transportation infrastructure more efficiently. Dynamic traffic assignment (DTA) models can play a critical role in the design of information provision systems by modeling how drivers react to information (descriptive use), and also in determining the optimal traffic state, which can be the goal of the information provision strategy (prescriptive use). DTA models based on the latter principle can also be of great value in off-line operational planning tasks. This paper describes some experiences with off-line applications of this kind of model. The DTA model consists of two independent components: a routing model and a traffic simulation model. These two models are executed iteratively in a feedback scheme that progressively improves the assignment of vehicles to paths until approximate user-equilibrium conditions are achieved. Model predictions are compared to empirical traffic counts, with very positive results.