Transportation Impacts of Berkeley Hills Tunnel Disruption by Earthquakes

In the San Francisco Bay Area, earthquake damage to a small number of critical transportation facilities can produce regionwide mobility impacts. This report evaluates the Berkeley Hills Tunnel, a key Bay Area Rapid Transit (BART) cross-hills connection, using an integrated model that links tunnel seismic performance to transportation consequences during disruption and recovery. The model couples scenario-based seismic assessment of the tunnel with screening-level fragility for substitute corridors and propagates the resulting time-dependent capacity states through a transportation simulation. At a representative recovery-stage demand of 25 percent of normal, mean cross-hills travel time rises from about 9 minutes in the mildest scenario (327-year return period) to about 41 minutes in the most severe (654-year). In that severe case, a fully subscribed bus bridge can lower the mean cross-hills travel time by up to 30 percent. Uncertainty quantification identifies recovery-stage demand as the dominant source of travel-time variance and shows that unfavorable capacity combinations can nearly double travel time relative to the central estimate. Disruption falls disproportionately on transit-dependent travelers, who either endure longer travel times or pay an extra travel fee. Agencies can use the workflow to assess disruption impacts and identify likely bottlenecks, compare recovery-stage operational strategies, and target equitable service for affected populations.