The Dumbarton Bridge is the southernmost of the highway bridges that span the San Francisco Bay in California. Carrying over 81,000 vehicles daily, it is also the shortest bridge across San Francisco Bay at 1.63 miles (8,600 feet / 2,622 m). Its eastern terminus is in Fremont, near Newark in the San Francisco Bay National Wildlife Refuge, and its western terminus is in Menlo Park. The bridge has three lanes in each direction, and features a separated bike/pedestrian lane on its south-facing side. Like the San Mateo Bridge to the north, power lines parallel the bridge across the bay.
Tolls are collected in the westbound direction at the toll plaza, which is located on the eastern side of the bay; the toll is $5 as of 7/1/10. There are six toll lanes at the plaza; the leftmost two are dedicated FasTrak lanes. An additional carpool lane to the left of these can be used only for half off by vehicles using FasTrak during weekday morning and afternoon commute hours by vehicles carrying two or more persons, motorcycles, or hybrid vehicles with a permit decal.
When the current bridge was planned in the 1970s, Caltrans conducted extensive environmental research on the aquatic and terrestrial environment. Principal concerns of the public were air pollution and noise pollution impacts, particularly in some residential areas of Menlo Park and East Palo Alto. Studies were conducted to produce contour maps of projected sound levels and carbon monoxide concentrations throughout the western approaches, for each alternative connection scheme.