ATTN: IB 1 blocked on Sacramento between Larkin and Hyde by #SFFD activity. Expect IB 1 delays and possible reroute. (More: 11 in last 48 hours)

Central Subway Construction Update 1/13/17

Thank you for your interest in the Central Subway Project, which is a significant project in the history of San Francisco's public transportation network. This project is the first underground line to link the north and south corridors of the city, and will provide a direct connection to major retail, sporting and cultural venues while efficiently transporting people to jobs, educational opportunities and other amenities throughout San Francisco.

This is an exciting time as the San Francisco Municipal Transportation Agency's | Central Subway team works to construct a vital transportation link that, when open in 2019, will improve connectivity for the city.

Workers signal to an excavator operator to make way for a larger machine to be used to excavate a portion of the north platform cavern of the Chinatown Station.

Central Subway | Project Advancement

January 13 through January 22, 2017

This notice provides a construction update and a look ahead for what to expect in the areas where we are building four new stations along the alignment. You’ll find information about work activities, traffic and transportation impacts taking place over the next two weeks at SoMa, Yerba Buena/Moscone, Union Square and Chinatown.

Construction schedules, bus routes, and stop locations are subject to change due to unforeseen conditions. Signs will be posted at affected stops to advise of service changes.

Our thanks go out to the businesses, residents, shoppers, commuters, and all those who are touched by the Project, for their continued engagement as we work to extend the city's public transportation system.

The Central Subway Team

Workers have poured a new curb and gutter at Townsend as part of street restoration efforts.

Surface Station, Trackwork and Systems

Work along 4th Street between Bryant Street and King Street includes construction of a surface station between Bryant Street and Brannan Street. The construction team is upgrading utilities and trackwork on 4th Street between the tunnel portal at Bryant Street and the connection with the existing light rail system at King Street.

Vehicular access to 4th from Welsh Street will be temporarily detoured, due to sewer construction activity at that intersection.  Night work is ongoing on 4th Street between Bryant and King Streets, between 8:00 PM and 5:00 AM.  Utility installation and upgrade work continues along 4th Street between Bryant and King, and regular day shift hours are from 7am to 4pm.

Utility installation work continues at the 4th and Brannan intersection.

Sewer installation work continues at 4th and Welsh.  A detour for access to 4th from Welsh is temporarily in effect.

Overview

  • Night work between King and Bryant
  • Sewer improvement work
  • Utility installation
  • Sewer manhole installation
  • Relocation of communication lines

Details

What: Night utility work between King and Bryant
Time: 8 p.m. - 5:00 a.m.
When: Monday to Saturday
Where: 4th Street between King and Bryant
What: Utility installation work

What: Pavement renovation
Time: 7 a.m. - 5:30 p.m.
When: Monday to Saturday
Where: 4th Street between King and Brannan

What: Installation of manhole structure, duct bank, utility installation
Time: 7 a.m. - 4 p.m.
When Monday to Friday
Where: 4th Street at Brannan

What: Relocation of communications lines
Time: 7 p.m. - 5 a.m.
When: Monday to Friday
Where: 4th Street at Brannan

What to expect

  • Work may involve saw-cutting, potholing and jack-hammering on the roadway and sidewalk
  • Sidewalk access may be limited
  • Access will remain open for pedestrians and businesses 
  • Parking and Traffic Impact
    • Vehicular access to 4th from Welsh Street has been temporarily detoured.
    • Partial lane closures on 4th Street between Townsend and King streets.
    • Detours will be in place. The crosswalk may be disrupted. Alternative pedestrian walkways will be in place.
    • Parking will be unavailable in the work area on both sides of 4th Street.
    • Two lanes of traffic open on the west side of 4th Street.
    • Traffic impacts are in effect 24 hours a day.
  • Muni Impact
    • No scheduled impacts at this time.

Interior walls and emergency stairs are being constructed on the top two levels of the station box.

Yerba Buena | Moscone Station

4th Street from Howard to Folsom

Work along 4th Street between Howard Street and Folsom Street consists of construction of the underground Yerba Buena | Moscone Station. The cut and cover method known as a "top-down" or "bottom-up" approach involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

Excavation of the Yerba Buena/Moscone Station underneath 4th Street between Folsom and Clementina continues.  The current traffic configuration from north of the station to Howard Street will remain, but may change in the coming weeks.  Excavation and installation of temporary bracing continues at the station platform level.

The west side of 4th Street south of Howard is currently being restored.

Inside the north emergency egress stairwell of the station box.

Overview

  • Excavation of the headhouse and station box and installation of temporary bracing
  • Roadway and sidewalk restoration on 4th south of Howard

Details

What: Excavation of the headhouse and station box and installation of temporary bracing
Time:  7a.m - 7p.m.
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street

What: Roadway restoration on the west side of 4th Street south of Howard
Time:  7a.m.- 4p.m.
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street What to expect

  • Clementina Street is closed at 4th Street
  • The sidewalk on the west side of 4th Street is closed south of Howard
  • Parking and Traffic Impact
    • Two lanes of traffic open on the east side of 4th Street
  • Muni Impact
    • No scheduled impacts at this time

    A crew suspends and welds a large steel beam which will be used as a bracket to hold temporary bracing inside the station box.

    Union Square | Market Street Station

    The construction of an underground Union Square|Market Street Station uses the cut and cover method known as a "top-down" or "bottom-up" approach and involves construction of a box frame structure within a trench excavation that is subsequently backfilled. Some work continues at night along Stockton Street between Ellis Street and Post Street.

    O'Farrell Street at Stockton may be narrowed to one lane at night to allow for the removal of excavated materials. The installation of waterproofing and concrete at the southeast corner of the Union Square Garage continues.  There will be an increase in vehicles and activities at this location as work ramps up.  Station excavation and installation of temporary bracing is ongoing under Stockton Street as well as on O'Farrell.

    Workers inspect steel mesh and install a section of conduit on the east wall of the station box.

    A worker emerges from the north concourse, adjacent to the future entrance at the Union Square Garage.

    Overview

    • Partial backfill and utility work at the Ellis and Stockton intersection
    • Potential nighttime closure of Ellis and Stockton pedestrian crossing
    • Station excavation and installation of temporary bracing
    • Union Square Garage plaza level concrete installation

    Details

    For all activities, construction hours may be 24 hours a day, Monday to Saturday, Sunday work may be required What to expect

    • Pedestrian access to Stockton Street between Geary and Ellis is now limited to sidewalks, as work as resumed following the end of the 2016 work moratorium
    • Sidewalk access may be limited at times
    • Parking and Traffic Impact
      • Stockton Street between Ellis Street and Geary Street is closed to vehicular traffic
    • Muni Impact
      • No scheduled impacts at this time.

    Excavation work has begun on the left side drift of the north platform cavern.  All four side drifts are now being excavated simultaneously.

    Chinatown Station

    The construction of an underground Chinatown Station uses the sequential excavation method (SEM) along Washington Street and Stockton Street. The SEM provides a high degree of flexibility during construction and makes it possible to control virtually all kinds of ground conditions, thereby greatly reducing the risks of construction. This method of tunnel construction is used worldwide for small to large openings in a variety of ground types ranging from rock to soil.

    Sprayed concrete (shotcrete) and other supporting elements are applied and installed promptly after exposing ground, which provides a safe and stable opening.

    Current activities include excavation of the north and south platform caverns. The contractor completed barrel vault installation mid-November and then began breakout and excavation of the platform cavern side drifts.

    Two men discuss operations while shotcrete work is performed far behind them.


    A large bulldozer and sections of drill pipe rest inside the right side drift of the north cavern.

    Overview

    • Excavation of station headhouse
    • Excavation of the north and south platform caverns

    Details

    What: Station site excavation
    Time: 24 hours
    When: Monday to Saturday
    Where: Stockton Street and Washington Street

    What to expect

    • Sidewalk access may be limited at times
    • PG&E may be performing night work from 7pm to 6am at Washington and Stockton, Monday through Saturday.
    • Parking and Traffic Impact
      • No parking on both sides of Stockton Street between Washington Street and Jackson Street
      • One lane of traffic on both sides of Stockton Street between Washington Street and Jackson Street
      • Washington Street:
        • remains closed between Stockton Street and Trenton Street
        • is converted into a two-way street between Powell Street and the construction zone
    • Muni Impact
      • No scheduled impacts at this time.

    Connecting People. Connecting Communities.

    Contact Us: If you have questions about construction or the Central Subway Project you can email us at central.subway@sfmta.com or leave a message at (415) 701-4371.

    For More Information: The Central Subway team posts frequent project updates on a variety of social media outlets. To find out more about the project and construction progress, follow us on Facebook, Twitter, or Flickr.

    Construction schedules are subject to change.