Abstract:
The Atlanta Regional Commission (ARC) travel demand model is designed to, at minimum, represent the state of the practice and meet all modeling requirements specified in the U.S. Environmental Protection Agency Transportation Conformity Rules. Since 1990, a full consultation process, peer reviews and the ARC strategic travel demand model enhancement program have guided all modifications to the travel demand model. As a result, each element of the travel demand model is designed to support all technical and policy decisions that are required in developing multimodal planning and programs under the Intermodal Surface Transportation Act of 1991 (ISTEA), and the 1990 Clean Air Act Amendments (CAAA). Priority was given to those model improvements essential for the creation of a travel demand model that meets all federal planning and air quality requirements, and sufficiently represents all transportation modes in the Atlanta region. The ARC strategic travel demand enhancement program includes the following priorities: the implementation of full model "feedback" of congested travel times, creation of separate High Occupancy Vehicle trip tables and assignment procedures; creation of time-of-day highway assignments; implementation of empirical speeds in all relevant elements of the travel demand model; preparation of composite travel impedances for use in the DRAM/EMPAL land use model; and the creation of a speed sensitive emissions estimation procedure for MOBILE 5b. The ARC model enhancement program was completed and fully implemented as part of the 2025 RTP and 2001-2003 TIP development. The paper includes a detailed technical description of the ARC regional travel demand model and the ARC link-based emissions post processor.