Simulation Model Performance Evaluation for Congested Freeway Operations (7-3943-S)

Recent and continuing growth has resulted in increased demand for travel on urban freeways across Texas. Many freeways are operating under congested conditions throughout much of the day. Proposed operational improvements for these freeways are difficult to evaluate or to simulate accurately because of the increased effect of vehicle interactions and impact of design elements on traffic flow, which occur under congestion. Improvements in recent years to traffic models offer promise in the simulation of congested freeways and freeway elements (e.g., ramps, merges, and weaving areas). The more promising models simulate vehicle interactions, lane changing, car following, and vehicle rerouting; accommodate origin-destination information; and in general try to model driver behavior. However, the lack of a universally accepted model for simulating congested conditions highlights the need for a study to determine which models produce the best results under different congested conditions. See Figures I and 2 for sample data output. The objectives of this research were to select appropriate models for simulating congested freeways, test the calibration and validation performance of those models using data collected on Dallas freeways, and provide recommendations for the use of the best model for congested freeways in Texas.