|Locale||San Francisco Bay Area|
|Service area||Alameda, San Mateo, and Santa Clara Counties|
|Service type||bus service|
Dumbarton Express is a regional public transit service in the San Francisco Bay Area connecting Alameda, San Mateo, and Santa Clara Counties via the Dumbarton Bridge. The Transbay bus service is provided under a consortium of five transit operators (AC Transit, BART, SamTrans, Union City Transit, and VTA). Dumbarton Express is administered by AC Transit. It was also operated by AC Transit through 16 December 2011; MV Transportation assumed operations effective 19 December 2011.
As of 12 December 2012, Dumbarton Express operates two bus lines.
|Route||Terminals||Days of Operation||Cities and Communities Served||Connecting Rail Station(s)||Schedule Information|
|DB||Union City BART||Stanford Oval||Weekdays (including middays)||Union City, Newark, Menlo Park, Palo Alto||Union City BART, Palo Alto Caltrain||Route DB Schedule|
|DB1||Union City BART||Stanford Research Park
(Deer Creek & Page Mill)
|Weekdays (commute only)||Union City, Newark, Palo Alto||Union City BART||Route DB1 Schedule|
Dumbarton Express has an "open door" policy that allows local service in the East Bay and Peninsula.
|Fare category||Local one way||Transbay one way||Transbay one way upgrade from local fare|
|Senior (65+), disabled (), and Medicare||$1.05||$2.10||$1.05|
Note: Local travel is within the East Bay or Peninsula; Transbay travel is across the Dumbarton Bridge.
Dumbarton Express accepts transfers and passes from several connecting transit agencies for full or partial fare.
VTA Express Eco Passes and AC Transit Transbay 31-Day Passes are accepted as full Transbay fare.
The following are accepted as full local fare or partial Transbay fare:
BART-to-bus transfers are accepted as full local fare but not as partial Transbay fare. As of 1 January 2013, BART Plus tickets are not accepted.
Transfers issued by Dumbarton Express are valid for 2 hours and are accepted by AC Transit, SamTrans, Union City Transit, and VTA. Union City Transit has a $0.25 surcharge, payable on board Union City Transit. Transfers to SamTrans are valid only for passengers using Clipper cards.
On August 2, 2017, SamTrans, one of the five transit agencies that jointly operate the Dumbarton Express, released a study that examined the feasibility of adding additional bus routes to the service. The study recommended two new bus routes: an express bus route traveling between the Union City BART station to the Redwood City Caltrain station, and a local bus route between the Union City BART station to job centers in northern Mountain View and Sunnyvale, the introduction of which would lead to a 34% increase in ridership. The study also reiterated SamTrans' ultimate goal of reintroducing rail service across the Dumbarton Rail Bridge, ultimately connecting the Redwood City Caltrain station to the Union City BART station via conventional passenger rail.