The Dumbarton Rail Corridor is a proposed transbay passenger rail line which would reuse the right-of-way that was initially constructed from 1907–1910 as the Dumbarton Cut-off. The Dumbarton Cut-off includes the first structure to span San Francisco Bay, the 1910 Dumbarton Rail Bridge, although the vintage Cut-off bridges would likely be replaced prior to activating new passenger service. Dumbarton Rail Corridor would provide service between Union City in the East Bay (where passengers could connect with BART, ACE and Capitol Corridor trains) and Menlo Park on the Peninsula, with train service continuing to both San Francisco and San José along the existing Caltrain tracks. It has been in the planning stages since 1988, and would be the first above-ground transbay rail line since Key System electric trains stopped running on the lower deck of the Bay Bridge in 1958, and the first new transbay crossing of any kind since the completion of the Transbay Tube in 1974.
Route description
The Dumbarton Rail Corridor service, as proposed in 2006, would provide six westbound trains originating from the Union City BART station, rebuilt as an intermodal station; after crossing the rebuilt Dumbarton Cut-off bridges, the trains would join the existing Peninsula Corridor (Caltrain) line south of the existing Redwood City station. Three trains would proceed north to San Francisco and three trains would proceed south to San Jose. In the afternoon, the six trains would return from San Francisco and San Jose to Union City. The initial service offering would not include reverse commute (west-to-east in the mornings and east-to-west in the afternoons), mid-day, evening, or weekend trains.
Hayward to Centerville (Segments G/F) Part of the Dumbarton Rail Corridor plans include a new connection between the Oakland subdivision (running generally north–south) and the Centerville line (running generally east–west) near Shinn Street, east of the Fremont–Centerville station. Trains originating in Union City would enter the Shinn connection, turning right from southbound to westbound, and pass under the BART tracks before joining the Centerville line. Freight traffic would be rerouted from the Oakland Subdivision to the parallel Niles Subdivision, slightly to the east. Other proposed improvements included a proposed fourteen-span bridge over Alameda Creek to separate freight and passenger traffic. Use of this segment would require acquisition of the right-of-way from Union Pacific. Capitol Corridor trains would be rerouted to the Oakland subdivision to share service at the Union City intermodal station.
A new layover yard would be required for overnight storage of trains. The layover yard was proposed to be north of Whipple Road in Hayward, and would provide overnight storage for trains entering the Union City station, rebuilt for intermodal service. Heavy maintenance activities (including refueling) would be performed at Caltrain yards on the Peninsula. A new segment, the Industrial Parkway connection, would be constructed to connect the Oakland subdivision and the Niles subdivision north of the layover yard.
Centerville to Newark (Segments E/D/C) This segment would reuse the existing Dumbarton Cut-off line west of Newark Junction. Between Newark Junction and Fremont Centerville station, the segment would run on the Union Pacific Centerville line.
Newark to Menlo Park/East Palo Alto (Segment B) This segment would reuse the existing line established for the Dumbarton Cut-off in 1910. It would be a single-track line with two sidings, one industrial siding to serve the Cargill Salt Plant and one future siding just east of the Dumbarton Rail Bridge. The industrial siding would be the existing line, with a new main line constructed around the salt loading facility.
The two swing bridges and their timber trestle approaches were known to be in poor shape since 1996, and a subsequent 2008 engineering investigation found the concrete foundations were also degraded, possibly since they were constructed in 1910. The 2003 Project Study Report proposed replacement of the Dumbarton Rail Bridge swing span with a bascule, replacement of the Newark Slough Bridge with a steel girder swing span, and new concrete trestles.
Menlo Park/East Palo Alto to Redwood City (Segment A)
The existing two-track Dumbarton Cut-off line would be converted to a single track system with centralized traffic control; the second track would be retained as a siding in certain portions. This segment would include the proposed Willow Road and Redwood City (Second Avenue) stations. The Dumbarton Rail Corridor merges with the Peninsula Corridor in Redwood City at the Redwood Junction, which is a large wye roughly bounded by Middlefield Road, Woodside Road, El Camino Real, and Dumbarton Avenue.
Redwood City to San Francisco Once on the Peninsula corridor, northbound morning trains would provide limited stop service at existing Caltrain stations in Redwood City, Hillsdale, San Mateo, Millbrae, South San Francisco, and San Francisco, with afternoon trains returning to Union City making the same stops, in reverse order.
Menlo Park to San Jose Once on the Peninsula Corridor, southbound morning trains would stop at Menlo Park, Palo Alto, California Avenue, Mountain View, and San Jose, with afternoon trains returning to Union City making the same stops, in reverse order.
Stations
From Union City, trains would stop at stations in Fremont (Fremont–Centerville station), Newark and Menlo Park/East Palo Alto before joining the main Caltrain line at Redwood City (northbound) or Menlo Park (southbound), with limited service to San Francisco or San Jose, respectively. Two more stations could be added in Redwood City (2nd Avenue) and Hayward (Hayward BART) if rider participation would justify the cost.
Hayward The existing Hayward BART station could be rebuilt as an intermodal station and serve as the terminus for the Dumbarton Rail Corridor at a future date if ridership projections warrant. If Capitol Corridor trains are rerouted onto the Oakland subdivision, the existing Hayward stop would likely be moved to the new intermodal station.
Separately, Capitol Corridor has been considering moving trains on to the Mulford/Coast subdivision, the westernmost railroad in Alameda County, partially sharing the route for the Coast Starlight, which would discontinue service to Hayward and Fremont Centerville, and bypass Union City entirely.
Union City
The existing Union City station was rebuilt as an intermodal station serving BART and AC Transit. Phase III of the intermodal station project would create a commuter rail station for Dumbarton Rail, ACE, and Capitol Corridor trains, linked to the BART station with a passenger bridge. The commuter rail station would be adjacent to the east side of the existing BART station.
Phase I of the Intermodal Station project was completed between 2007 and 2010, focusing on bus transit connections and west-side BART station improvements. Phase II focused on improving the east side of the BART station and preparing it for intermodal service with commuter rail.
Fremont Centerville The existing Fremont Centerville station would add service for the Dumbarton Rail Corridor trains. The south platform would be rebuilt for Dumbarton Rail Corridor service, and new parking spaces would be added.
Newark A new station would be constructed in Newark just west of Willow Street, south of Thornton Avenue. The Newark Station would feature a side platform south of the tracks, with space left for a future second main track.
Willow Road A new station would be constructed in the Belle Haven neighborhood of Menlo Park, just west of Willow Road and south of State Route 84 (the Bayfront Expressway). Willow Road Station would feature one side platform south of the tracks.
Redwood City (2nd Ave) A new station could be constructed just east of the Redwood Junction, again presuming ridership projections warrant another station.
History
1910–1982: Dumbarton Cut-off
The Central California Railway Company, a subsidiary of Southern Pacific, completed the Dumbarton Cut-off in 1910, reducing the rail route distance between Oakland and San Francisco by . Prior to the completion of the Cut-off, transcontinental freight destined for San Francisco was unloaded in Oakland and ferried across the Bay, or trains detoured through San Jose and Santa Clara, using the Peninsula Corridor to San Francisco. The Dumbarton Rail Bridge, a swing through-truss span, was the first structure built across San Francisco Bay. The Dumbarton Cut-off includes a second, smaller swing through-truss to the east of the Dumbarton Rail Bridge.
Some portions of the timber trestles had been replaced with concrete structures in the 1960s and 1970s. However, San Francisco gradually became a less important hub for rail transportation, and the Port of Oakland was better-suited to handle containerized shipping. The last freight train used the Dumbarton Cut-off in 1982.
1988–2001: Initial studies
The San Mateo County Transit Authority (SMCTA) was created following the passage of 1988's Measure A, a half-cent sales tax increase in San Mateo County which set aside for the purchase of the "Dumbarton S.P. Spur from Redwood City to Fremont." A 1991 study sponsored by SMCTA, the Dumbarton Commuter Service Feasibility Study (Parsons Brinckerhoff) recommended a rail option along the former Dumbarton Cut-off as a long-term strategy. Pursuing this strategy, SamTrans purchased the entire right-of-way for in early 1994, with the help of a loan from Caltrans. More studies followed in 1996 (Dumbarton Rail Corridor Rehabilitation, Morrison Knudsen), 1997 (Dumbarton Corridor Study, Parsons Brinckerhoff), and 1998 (Dumbarton Corridor Transit Concept Plan), which concluded that trans-Bay rail was viable as a long-term strategy and expanded bus service could serve as a short-term strategy.
A suspected arson fire destroyed part of the western timber trestle approach to the Dumbarton Rail Bridge in January 1998, although the 1996 Dumbarton Rail Corridor Rehabilitation report (confirmed in a later 1999 study) had already concluded the timber trestles would need to be replaced. In 1998, the estimated cost for reactivating Dumbarton passenger rail service was .
That 1999 study (the Dumbarton Rail Corridor Study, Parsons Transportation Group) put the Dumbarton rail project into the 2000 report Blueprint for the 21st Century, sponsored by the Metropolitan Transportation Commission (MTC). The 1999 report evaluated the cost estimates for rehabilitating the line from the 1996 report and concurred that the timber trestles should be replaced,Parsons, Dumbarton Rail Corridor Study, (July 1999)."Section 4.1.3: Based on the inspection report and field data collected, it is clear that the remaining timber trestle spans (bridge items 1, 6, 7 and 9), built in 1908, are in the [sic] imminent danger of collapse and need to be replaced." the lower portion of the steel through-trusses should be replaced,Parsons, Dumbarton Rail Corridor Study, (July 1999)."Section 4.1.5: According to the MKC assessment report, the entire lower portion of the trusses, which is close to the water, is severely corroded and should be replaced." and the two swing spans were severely corroded but operable in 1996.Parsons, Dumbarton Rail Corridor Study, (July 1999)."Section 4.1.6.1: According to the MKC report, these two swing spans are severely corroded. The truss members required extensive rehabilitiation. The Dumbarton bridge fenders need to be replaced. Section 4.1.6.2: Mechanical systems were inspected while observing a bridge operation. Therefore it can be concluded that the equipment is operable." The 1999 Dumbarton Rail Corridor Study estimated the necessary improvements would cost a total of .