Central Subway Project

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Project Introduction

Welcome to the New Central Subway!

San Francisco recently opened its first new subway in over 40 years, with three new underground stations and one above-ground station joining the Muni Metro T Third line. By extending the T Third 1.7 miles through SoMa, Union Square and Chinatown, there is now faster, smoother transit service between some of the city’s busiest, most vibrant areas.

The new T Third line from Chinatown Rose-Pak to Sunnydale started on January 7, 2023, Monday through Friday, 6 a.m. to 12 a.m., and Saturdays and Sundays, 8 a.m. to 12 a.m. The new T Third line continues to provide service along 3rd and 4th streets and now extends north to four new stations: 4th & Brannan, Yerba Buena/Moscone Station, Union Square/Market Street Station and Chinatown-Rose Pak Station. The T Third is no longer running along King Street, the Embarcadero or Market Street.

    Project Timeline
    Design
    2009-2013
    Completed
    Construction
    2011 - Spring 2021
    Pending
    Testing
    2021-2022
    Pending
    Revenue Service
    Winter 2023
    Pending
    Project Status
    1. Implementation / Construction
    2. Current
    Improvements
    Muni Metro train
    bus
    bike
    walking
    SFMTA Accessibility icon
    Streetscape
    Bus Routes and Rail Lines
    Neighborhoods
    Financial District
    South of Market (SoMa)
    Downtown / Civic Center
    Chinatown
    Streets
    Stockton Street, 4th Street

    Project Background

    Planning for Central Subway began in the late 1980s to provide more transit on 3rd Street and in Chinatown. After six years of construction, the first part of the T Third opened on 3rd Street in 2007. It connects neighborhoods in Mission Bay, Bayview, Hunter’s Point and Visitacion Valley. In 2013, work began to add 1.7 miles to the T Third, with four new stations in SoMa, Union Square and Chinatown. Tunnels over a mile long under the streets are as deep as 120 feet in some areas. The project cost $1.9 billion, provided by the Federal Transit Administration, the State of California, the Metropolitan Transportation Commission, the San Francisco County Transportation Authority and the City and County of San Francisco.

     

    Project Implementation

    Construction Phase

    • Building launch box for tunnel boring machines on 4th between Harrison and Bryant
    • Excavating tunnels by tunnel boring machines beneath SF
    • Building stations, surface tracks, and systems
    • Installing new track interchange at 4th and King and 4th Street surface tracks
    • Completing major excavation for Yerba Buena/Moscone Station and Union Square/Market Street Station and pivoting work toward interior construction

    Testing Phase

    • Inspecting fire sprinklers installed in tunnels to ensure they respond to fire alarm activation
    • Testing emergency ventilation fans for adequate tunnel air supply and extraction
    • Conducting safety drills and developing contingency plans in the event of a passenger evacuation or first responders needing access to an incident in the tunnel
    • Verifying automatic train control system guides the automatic movement of light rail vehicles properly through tunnels
    • Assessing radio and data communication systems for effective delivery of audio and visual announcements to customers and automatic vehicle location data to the Transportation Management Center
    • Inspecting customer information system and certifying Metro audio announcements and displays are working correctly.

    Service

    Service for the Central Subway has begun with free weekend-only service between Chinatown-Rose Pak and 4th/Brannan stations, followed by revenue service beginning January 7, 2023 seven days a week between Sunnydale and Chinatown. During the final phase, project staff will continue to engage our community partners in Bayview, SOMA, Union Square and Chinatown and inform customers about the service changes to Muni’s Metro system.

       

    Additional Resources

    Office Hours

    Have a question about the Central Subway Project?  Stop by our construction office to get assistance from project staff during our Community Drop-In Office Hours:

    Central Subway Project Office
    530 Bush St. Suite 400 (4th Floor)
    M-F 9am to 5pm

    Funding

    The Central Subway Project is funded by the Federal Transit Administration (FTA), the State of California, the Metropolitan Transportation Commission, the San Francisco County Transportation Authority and the City and County of San Francisco.

    The majority of funding for the Central Subway Project is provided by the FTA’s New Starts program, with a total commitment over the life of the project of $948.4 million. An additional $41 million in federal funds is designated to the project as part of the U.S. Department of Transportation’s Congestion Mitigation and Air Quality Improvement Program, which supports environmental efforts for surface transportation and related projects. The federal funds allocated for the Central Subway Project cannot be redirected for investment in any other San Francisco projects.

    The San Francisco Municipal Transportation Agency’s (SFMTA) baseline budget for the Central Subway Project is approximately $1.95 billion. There has been no increase in the local funding commitment since original voter approval in 2003 of $126 million in Proposition B/K sales tax funds.

    In total, about half of the funding for the entire Third Street Light Rail Transit Project is from federal sources, with the remaining half from state and local sources.  The Central Subway Project is one of the nation’s highest-rated projects in the FTA's New Starts program.

    Project video(s)
    The forward portion of tunnel boring machine Mom Chung is seen being assembled. A mining service vehicle enters TBM Mom Chung during southbound tunnel construction. A look inside the forward shield portion of TBM Big Alma during northbound tunnel construction. Workers attach new sections of utility pipes and conduit to the southbound tunnel wall as the trailing gear moves forward. TBM Big Alma emerges (left) alongside TBM Mom Chung (right) inside the North Beach retrieval shaft. Project and agency staff watch TBM Big Alma emerge inside the North Beach retrieval shaft in 2014. Following the completion of tunneling, both TBMs are disassembled and removed from the North Beach retrieval shaft. View looking north inside the tunnel portal under 4th Street between Harrison and Bryant. Two men ready a section of drill casing before lifting it up the ramp to the drill rig positioned as part of grouting work for t A clear view looking north down the Union Square/Market Street station invert, following the removal of temporary bracing. Workers construct final structural elements of the Yerba Buena/Moscone station platform. Concrete forms are constructed for future emergency egress stairs on the east side of Stockton at O'Farrell. A crew pours concrete around future elevator footings inside the Yerba Buena/Moscone station box. A metalworker cleans up the ends of a large steel I-beam for welding, which will be used as a bracket at the south headwall. Workers traverse the site carefully during the last of the tunnel portal invert concrete pour, completing the foundation and roa Two short sections of rail are welded together using this machine near 4th and Bluxome. Another length of rail is lifted into place onto steel rollers to be moved north up 4th Street. A large bulldozer approaches the excavation spoils collection and sorting area under the main access shaft inside the Chinatown A carpenter builds part of a concrete form in the northwest corner of the YBM station headhouse. Two men weld and shape steel brackets along the east wall of the station box, near the south UMS headwall. A worker walks atop the rebar cage of the invert slab at the north end of the Union Square/Market Street station box. A carpenter cuts a 2x4 as part of concrete form assembly inside the YBM station headhouse. Curved formwork mark the edges of future curbs and gutters during sidewalk restoration work at 4th and Townsend. Workers use a shotcrete spraying machine inside the top header of the north platform cavern of Chinatown Station. Carpenters cut boards to build cross-bracing as part of concrete form construction at the south headwall of the UMS station box. Workers signal from the bottom of the Yerba Buena/Moscone Station headhouse to the surface. Prepared strands of rebar wait at the surface worksite just north of O'Farrell to be lowered into the UMS station box. Drill casings surround a worker pausing for a bulldozer to pass during excavation of the Chinatown Station platform cavern. Workers check rail spacers, mounting bolts, and rebar as preparation before pouring concrete for future track plinths at YBM. Steel mesh and shotcrete are being installed at the south headwall of the UMS station box, just south of O'Farrell and Stockton. Sections of rail are bolted down on the west side of the tunnel portal, just north of the 4th and Bryant intersection. Tourists, shoppers, and locals mingle at the first annual Winter Walk, held during the holidays on Stockton north of Market St.
     
    1. The forward portion of tunnel boring machine Mom Chung is seen being assembled.
    2. A mining service vehicle enters TBM Mom Chung during southbound tunnel construction.
    3. A look inside the forward shield portion of TBM Big Alma during northbound tunnel construction.
    4. Workers attach new sections of utility pipes and conduit to the southbound tunnel wall as the trailing gear moves forward.
    5. TBM Big Alma emerges (left) alongside TBM Mom Chung (right) inside the North Beach retrieval shaft.
    6. Project and agency staff watch TBM Big Alma emerge inside the North Beach retrieval shaft in 2014.
    7. Following the completion of tunneling, both TBMs are disassembled and removed from the North Beach retrieval shaft.
    8. View looking north inside the tunnel portal under 4th Street between Harrison and Bryant.
    9. Two men ready a section of drill casing before lifting it up the ramp to the drill rig positioned as part of grouting work for t
    10. A clear view looking north down the Union Square/Market Street station invert, following the removal of temporary bracing.
    11. Workers construct final structural elements of the Yerba Buena/Moscone station platform.
    12. Concrete forms are constructed for future emergency egress stairs on the east side of Stockton at O'Farrell.
    13. A crew pours concrete around future elevator footings inside the Yerba Buena/Moscone station box.
    14. A metalworker cleans up the ends of a large steel I-beam for welding, which will be used as a bracket at the south headwall.
    15. Workers traverse the site carefully during the last of the tunnel portal invert concrete pour, completing the foundation and roa
    16. Two short sections of rail are welded together using this machine near 4th and Bluxome.
    17. Another length of rail is lifted into place onto steel rollers to be moved north up 4th Street.
    18. A large bulldozer approaches the excavation spoils collection and sorting area under the main access shaft inside the Chinatown
    19. A carpenter builds part of a concrete form in the northwest corner of the YBM station headhouse.
    20. Two men weld and shape steel brackets along the east wall of the station box, near the south UMS headwall.
    21. A worker walks atop the rebar cage of the invert slab at the north end of the Union Square/Market Street station box.
    22. A carpenter cuts a 2x4 as part of concrete form assembly inside the YBM station headhouse.
    23. Curved formwork mark the edges of future curbs and gutters during sidewalk restoration work at 4th and Townsend.
    24. Workers use a shotcrete spraying machine inside the top header of the north platform cavern of Chinatown Station.
    25. Carpenters cut boards to build cross-bracing as part of concrete form construction at the south headwall of the UMS station box.
    26. Workers signal from the bottom of the Yerba Buena/Moscone Station headhouse to the surface.
    27. Prepared strands of rebar wait at the surface worksite just north of O'Farrell to be lowered into the UMS station box.
    28. Drill casings surround a worker pausing for a bulldozer to pass during excavation of the Chinatown Station platform cavern.
    29. Workers check rail spacers, mounting bolts, and rebar as preparation before pouring concrete for future track plinths at YBM.
    30. Steel mesh and shotcrete are being installed at the south headwall of the UMS station box, just south of O'Farrell and Stockton.
    31. Sections of rail are bolted down on the west side of the tunnel portal, just north of the 4th and Bryant intersection.
    32. Tourists, shoppers, and locals mingle at the first annual Winter Walk, held during the holidays on Stockton north of Market St.
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    Contact Information
    Enrique Aguilar
    Enrique.Aguilar@SFMTA.com