Dumbarton Bridge (California)
The Dumbarton Bridge is the southernmost of the highway bridges across San Francisco Bay in California. Carrying over 70,000 vehicles and about 118 pedestrian and bicycle crossings daily, it is the shortest bridge across San Francisco Bay at. Its eastern end is in Fremont, near Newark in the San Francisco Bay National Wildlife Refuge, and its western end is in Menlo Park. Bridging State Route 84 across the bay, it has three lanes each way and a separated bike/pedestrian lane along its south side. Like the San Mateo Bridge to the north, power lines parallel the bridge.
History and engineering features
The bridge has never been officially named, but its commonly used name comes from Dumbarton Point, named in 1876 after Dumbarton, Scotland. Built originally to provide a shortcut for traffic originating in San Mateo and Santa Clara counties, the bridge served industrial and residential areas on both sides. The earlier bridge opened on January 17, 1927, and was the first vehicular bridge to cross San Francisco Bay. A portion of this old drawbridge remains as a fishing pier on the east side of the Bay. The original bridge was built with private capital and then purchased by the state for $2.5 million in 1951.Its age and the two-lane undivided roadway and lift-span led to a replacement bridge being built to the north. This bridge opened in October 1982 as a four-lane, high-level structure. The structure was re-striped to accommodate six lanes on October 18, 1989, in response to the temporary closing of the San Francisco–Oakland Bay Bridge due to the Loma Prieta earthquake, and the permanent widening of the approaches was completed by July 2003. The cost of the complete replacement project was $200 million. The current bridge includes a two-way bicycle and separate pedestrian path on the south-facing side. A center span provides of vertical clearance for shipping. The approach spans on both sides of the Bay are of pre-stressed lightweight concrete girders supporting a lightweight concrete deck. The center spans are twin steel trapezoidal girders which also support a lightweight concrete deck.
The center span of the original bridge was demolished in a controlled explosion in September 1984.
Roadway connections
The bridge is part of State Route 84, and is directly connected to Interstate 880 by a freeway segment north of the Fremont end.There is no freeway connection between U.S. 101 and the southwest end of the Dumbarton Bridge. Motorists must traverse one of three at-grade routes to connect from the Bayshore Freeway to the bridge. These are :
- the Bayfront Expressway, a limited-access road linking to U.S. 101 at Marsh Road, Atherton
- Willow Road, an approximately one-mile expressway through east Menlo Park to U.S. 101
- University Avenue, an arterial road and the main commercial street of East Palo Alto.
Access to I-280 is available via State Route 84 to Woodside Road or other arterial routes. There are no cross-Peninsula freeway connections between State Routes 92 and 85. In addition, there are no direct cross-Peninsula arterial routes between State Route 84 and Page Mill Road, a five-mile gap.
Although the present situation has resulted in severe traffic problems on the bridge itself and in Menlo Park and East Palo Alto, Caltrans has been unable to upgrade the relevant portion of Highway 84 to freeway standards for several decades, due to opposition from the cities of Menlo Park, Atherton and Palo Alto. Freeway opponents fear that upgrading Highway 84 will encourage more people to live in southern Alameda County and commute to jobs in the mid-Peninsula area, thus increasing traffic in their neighborhoods to the south and west of U.S. 101 and even along State Routes 85 and 237.
Bus service across the bridge is provided by the Dumbarton Express, run by a consortium of local transit agencies which connects to BART at Union City and Caltrain at Palo Alto and California Avenue. AC Transit also runs Transbay buses U and DA across the bridge. The free Stanford Marguerite Shuttle also runs buses AE-F and EB across the bridge.
Environmental factors
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.The area around the bridge is an important ecological area, hosting many species of birds, fish and mammals. The endangered species California clapper rail is known to be present in the western bridge terminus area.
Near the bridge on the Peninsula are Menlo Park's Bayfront Park, East Palo Alto's Ravenswood Open Space Preserve, and the Palo Alto Baylands Nature Preserve. An accessible portion of the San Francisco Bay National Wildlife Refuge lies immediately north of the western bridge terminus, where the Ravenswood trail runs.
On both sides of the east end of the bridge are large salt ponds and levee trails belonging to the Don Edwards San Francisco Bay National Wildlife Refuge. The headquarters and visitor center for the refuge is on a hill south of the bridge approach. North of the east end of the bridge is Coyote Hills Regional Park, with its network of trails running over tall hills. North of that is the Alameda Creek Regional Trail from the Bay to Niles Canyon. East of Coyote Hills is Ardenwood Historic Farm, a restored working farm that preserves and displays turn-of-the-century farming methods
Tolls
Tolls are only collected from westbound traffic at the toll plaza on the east side of the bay. Drivers may either pay by cash or use the FasTrak electronic toll collection device. There are seven toll lanes at the plaza. During peak traffic hours, the leftmost lane is designated a FasTrak-only HOV lane, allowing carpool vehicles carrying two or more people or motorcycles to pass for a toll of $2.50. The next two leftmost lanes are FasTrak-only lanes for all vehicles, and all other lanes accept both cash and FasTrak. During non-peak hours the HOV lane is open to vehicles carrying only one person, but remains FasTrak-only.Historical toll rates
Prior to 1969, tolls on the Dumbarton Bridge were collected in both directions. When it opened, the original 1927 span had a toll of $0.40 per car plus $0.05 per passenger. In 1959, tolls were set to $0.35 per car. It was raised to $0.70 in 1969, then $0.75 in 1976. The toll per car remained at $0.75 when the replacement bridge opened in the 1980s.The basic toll on the seven state-owned bridges, including the Dumbarton Bridge, was raised to $1 by Regional Measure 1, approved by Bay Area voters in 1988. A $1 seismic retrofit surcharge was added in 1998 by the state legislature, originally for eight years, but since then extended to December 2037. On March 2, 2004, voters approved Regional Measure 2, raising the toll by another dollar to a total of $3. An additional dollar was added to the toll starting January 1, 2007, to cover cost overruns concerning the replacement of the eastern span.
The Metropolitan Transportation Commission, a regional transportation agency, in its capacity as the Bay Area Toll Authority, administers RM1 and RM2 funds, a significant portion of which are allocated to public transit capital improvements and operating subsidies in the transportation corridors served by the bridges. Caltrans administers the "second dollar" seismic surcharge, and receives some of the MTC-administered funds to perform other maintenance work on the bridges. The Bay Area Toll Authority is made up of appointed officials put in place by various city and county governments, and is not subject to direct voter oversight.
Due to further funding shortages for seismic retrofit projects, the Bay Area Toll Authority again raised tolls on all seven of the state-owned bridges in July 2010. The toll rate for autos on the Dumbarton Bridge was thus increased to $5.
In June 2018, Bay Area voters approved Regional Measure 3 to further raise the tolls on all seven of the state-owned bridges to fund $4.5 billion worth of transportation improvements in the area. Under the passed measure, the toll rate for autos on the Dumbarton Bridge will be increased to $6 on January 1, 2019; to $7 on January 1, 2022; and then to $8 on January 1, 2025.
In September 2019, the MTC approved a $4 million plan to eliminate toll takers and convert all seven of the state-owned bridges to all-electronic tolling, citing that 80 percent of drivers are now using Fastrak and the change would improve traffic flow. On March 20, 2020, at midnight, due to the COVID-19 pandemic, all-electronic tolling was temporarily placed in effect for all seven state-owned toll bridges.