Simulating protective cordon pricing to balance congestion management and affordability in San Francisco

Congestion pricing effectively manages road travel demand but raises affordability concerns for lower-income groups. This study evaluates potential implementations of cordon pricing in downtown San Francisco and their Bay Area-wide impacts. Using the BEAM CORE agent-based workflow, we compare flat-rate and income-based schemes, analyzing changes in accessibility, vehicle miles traveled, mode shift, energy use, and air quality. Both strategies reduce cordon-zone congestion and emissions while triggering external spillover effects, including increased vehicle miles traveled from rerouting, but also improved air quality. The income-based scheme protects lower-income households through reduced fees, yet exemptions alone cannot fully shield travelers: part of their accessibility loss stems from network reorganization rather than direct toll costs, a finding with implications for any income-tiered pricing design. Critically, congestion reduction and affordability need not be a zero-sum trade-off: the income-aware design achieves meaningful traffic reduction while cutting lower-income accessibility losses by 57% compared to flat-rate pricing.