Capability and Enhancement of VDANL and TWOPAS for Analyzing Vehicle Performanceon Upgrades and Downgrades Within IHSDM

摘要

The report documents the results and recommendations for designing and analyzing'Vehicle Performance on Upgrades and Downgrades' on two lane rural roads. The contract objective was to develop functional requirements to enhance the capability of the Interactive Highway Safety Design Model (IHSDM) in evaluating vehicle operations on upgrades and downgrades, and to provide outputs useful for evaluating grade steepness and the location and design of climbing lanes and emergency escape ramps. The analysis procedures involve the use of two simulation programs: VDANL, a vehicle dynamics simulation; and TWOPAS, a traffic flow simulation. This report includes recommendations for the best approach for applying both VDANL and TWOPAS, the planned improvements to the programs, and data collection and research needed for software enhancement, calibration, verification and validation. Case studies of an example upgrade and downgrade are also included to help support the recommended enhancements.