Calibration of a highway traffic assignment model for the Manhattan central business district

This paper describes the application of a traffic assignment model, specifically the TRANPLAN model, in New York City together with the methodologies and the satellite programs that were developed to accommodate the needs of the project. The traffic assignment module was modified to internally calculate capacities and delays at signalized intersections, based on the 1985 Highway Capacity Manual and utilize them in the calculation of travel times for the respective links. The base year trip table was developed from Origin-Destination surveys, but it was modified to account for the parking location of the vehicle, rather than the ultimate destination or origin of the driver. In order to reduce the calibration error in future forecasts, the model was enhanced with a procedure that combines the Fratar balancing technique with the Subarea Analysis module of TRANPLAN. Furthermore, the Subarea Analysis module was modified to incorporate travel paths in the development of the subarea trip table. This option becomes necessary when the subarea trip table is developed for a narrow corridor in a highly congested network.