Office of Planning, Environment, & Realty (HEP)
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The views expressed in this document do not represent the opinions of FHWA and do not constitute an endorsement, recommendation or specification by FHWA. The document is based solely on the discussions that took place during the peer review sessions and supporting technical documentation provided by San Francisco County Transportation Authority (SFCTA).
The FHWA wishes to acknowledge and thank the peer review panel members for volunteering their time to participate in the peer review of the SFCTA travel demand model (TDFM) and for sharing their valuable experience.
The Peer Review Panel Members were:
Brief biographies for each of the peer review panel members are presented in Appendix C.
This report is organized into the following sections:
In addition, the report includes the following appendices:
This report summarizes the results of a peer review of the SFCTA Dynamic Traffic Assignment (DTA) model. The peer review was supported by the Travel Model Improvement Program (TMIP), which is sponsored by FHWA. The peer review of a travel model can serve multiple purposes, including identification of model deficiencies, recommendations for model enhancements, and guidance on model applications. This peer review focused specifically on the DTA model being developed by the SFCTA, and not on the SFCTA's overall SF-CHAMP activity-based travel demand model system. Given the increasing complexities of travel demand forecasting practice and the growing demands by decision-makers for information about policy alternatives, it is essential that travel forecasting practitioners have the opportunity to share experiences and insights. The TMIP-supported peer review provides a forum for this knowledge exchange.
SFCTA's overall goal for model improvement and motivation for seeking a TMIP peer review is to obtain feedback on its ongoing efforts towards developing a DTA model and using it for analyzing proposed transit improvements, analyzing traffic diversions caused by those transit improvements, and comparing the effectiveness of roadway pricing alternatives. In order to make the project successful, the authority sought an assessment of the DTA model developed so far along with strategic guidance on calibration and validation of the model. The peer review panel was also requested to provide suggestions on how the agency's activity-based travel demand model, called SF-CHAMP (San Francisco's Chained Activity Modeling Process), may optimally be integrated with the DTA model currently in development. To that end, the peer reviewers spent one day discussing the needs and goals of the Authority and then responding to specific questions from SFCTA and its planning partners. The results of that discussion and recommendations from the panel are presented here. SFCTA and its partner agencies should carefully assess the feedback from the peers when prioritizing its final model development plan. While the advice of the peers is invaluable, there are many factors to work through when considering a model improvement strategy: the peer recommendations should be regarded as suggestions for SFCTA and its partners to consider rather than prescriptions to be followed.