Alameda-Contra Costa Transit
AC Transit is a major bus system serving the western side of Costa Costa and Alameda counties.
In addition to bus routes within the East Bay stretching from San Pablo south to Milpitas, AC Transit also operates express buses on the Bay Bridge to San Francisco, as well as on the San Mateo-Hayward Bridge and the Dumbarton Bridge to the Peninsula.
Most AC Transit bus routes connect with BART.