Calibration and Application of a Simulation-Based Dynamic Traffic Assignment Model

Abstract

The calibration and application of a simulation-based dynamic traffic assignment (DTA) model on a portion of the city of Calgary road network in Alberta, Canada, are discussed. The DTA model iteratively reassigns flow to paths by using the method of successive averages on the basis of travel times obtained with a traffic simulation model. The original subnetwork extracted from a regional planning model was enriched by a great increase in the number of zones. The DTA origin-destination matrix was estimated from an extensive database of turning movement counts via a trip generation/distribution model and a matrix adjustment algorithm. The network topology was enhanced by the addition of an interchange and a more precise representation of arterial intersections, including traffic signal control plans. A set of 1-h turning counts was used to calibrate the DTA model by adjusting local parameters such as gap-acceptance values, as well as global parameters such as average vehicle length. The final model results were compared with an independent set of 15-min turning movement counts. The resulting R2 values, which ranged from .91 to .96, lead to a high degree of confidence in the model results.