San Diego Association of Governments (SANDAG)
Since 2012, RSG has served as an on-call contractor for maintaining and enhancing the San Diego Association of Government’s (SANDAG’s) activity-based model. As part of these enhancements, SANDAG wanted to build a benefit-cost analysis (BCA) tool. The BCA tool would allow SANDAG to conduct a structured evaluation of transportation investment alternatives in the region. It would do this using outputs from their activity-based model, thereby lessening aggregation biases.
The BCA tool RSG developed incorporated several sources of benefits/costs. It also used detailed outputs from SANDAG’s activity-based travel demand model. This built on foundational work in the field. SANDAG’s model outputs (trip lists) were maintained in a SQL database. To improve the tool’s utility to SANDAG, we developed specialized SQL scripts, or code. The code tabulated changes in benefits relative to the reference point, applying standard benefit-cost calculations to the model outputs. It then summarized calculations across different market segments based on SANDAG’s interests. As a result, SANDAG could evaluate outputs across different income categories based on equity and environmental justice considerations.
SANDAG’s BCA tool, which is still in use by the agency, has facilitated side-by-side comparisons of different benefits across multiple scenarios and projects. Further enhancements to the BCA tool integrated it with SANDAG’s activity-based model. RSG also optimized it (to improve run times) and performed methodological enhancements. The SANDAG BCA tool was the basis for work on the BCA4ABM tool we developed for the Federal Highway Administration. Oregon Metro then later used BCA4ABM to develop its Multi-Criteria Evaluation (MCE) toolkit.