UPDATE: The OB 29 has resumed its regular route through the area of Beverly and Holloway. https://t.co/h7vf1DxYJX (More: 10 in last 48 hours)

Central Subway Construction Update 10/14/16

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. With the reinforced shotcrete dividers now removed, workers have backfilled half of the cross-cut cavern.  Once a ramp is built up, heavy machinery can be moved in. Central Subway | Project Advancement

October 14 through October 23, 2016

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 assemble rebar cages and concrete forms ahead of a concrete pour which will become the new roof of a section of century-old sewer. 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.

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.  The bus stop at the NE corner of 4th and Townsend will temporarily be relocated 140 feet to the east until November 4. Steel sheet piles are lowered into place to reinforce an excavation site at 4th and Bluxome. Workers have begun constructing a new road slab on the east side of 4th between King and Townsend. Overview

  • Night work between King and Bryant
  • Sewer improvement work
  • Utility installation
  • Sewer manhole installation
  • Installation of 36" and 48" sewer lines
  • 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: 78" Sewer Improvement
Time: 7 a.m. - 5:30 p.m.
When: Monday to Saturday
Where: 4th Street at Brannan Street

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: Installation of 36" and 48" sewer lines
Time: 7 a.m. - 4 p.m.
When: Monday to Friday
Where: 4th Street between Bryant Street and Freelon Street

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
    • Partial lane closures on 4th Street between Townsend and King streets, including full closure of northbound 4th Street.
    • 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
    • 4th Street and Townsend Street northwest corner bus stop utilized by 30 Stockton, 45 Union, 47 Van Ness, and 83X Mid-Market Express bus stop relocated 100 feet west
    • 4th Street and Townsend Street southwest corner bus stop temporarily relocated 80 feet west
    • 5th Street and Townsend Street bus stop temporarily discontinued
    • The bus stop at the NE corner of 4th and Townsend will temporarily be relocated 140 feet to the east until November 4.

Steel brackets are being welded to the exterior slurry walls, which will carry the weight of temporary reinforcing beams. 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.

Roadway excavation on the east side of 4th Street south of Howard began on Monday, October 10th, and will last several days.  Excavation of the Yerba Buena/Moscone Station underneath 4th Street between Folsom and Clementina continues.  The installation of utilities on 4th near Howard is ongoing. The current traffic configuration from north of the station to Howard Street will remain.  Excavation continues below mezzanine level.

A bundle of reinforcing steel is prepared to be lifted by crane at the staging area on the west side of 4th. Light pours in the platform level access portal, used to carry out excavated soil and bring in materials and supplies. Overview

  • Roadway excavation for utility work south of Howard
  • Excavation of the headhouse and station box
  • Water line replacement and sewer installation

Details

What: Roadway excavation for utility work
Time:  7a.m - 3:30p.m.
When: Monday to Friday
Where: East side of 4th Street south of Howard

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

What: Water line replacement and sewer installation
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
  • Parking and Traffic Impact
    • Two lanes of traffic open on 4th Street

Brackets are welded to the station's exterior walls while steel mesh is installed above, to reinforce shotcrete ahead of waterproofing. Union Square | Market Street Station

Work continues along Stockton Street between Ellis Street and Post Street. 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.

Work at Stockton and Ellis is ramping up, with the installation of a seismic joint.  Installation of waterproofing and concrete on the plaza level of the Union Square Garage continues.  There will be an increase in vehicles and activities as work at the southeast corner of Union Square ramps up.  Night work at the Stockton and O'Farrell intersection will reduce O'Farrell to one lane through the work area.  Current activities include station excavation and installation of temporary bracing under Stockton Street as well as on O'Farrell.

Workers erect safety railings atop large steel beams called walers inside the station box, where excavation is ongoing. A bulldozer driver shuttles excavated material back and forth from the station box to a collection area just north of Ellis. Overview

  • Seismic joint installation within work site at Stockton and Ellis
  • Traffic lane reduction at O'Farrell and Stockton due to night work
  • Station excavation and installation of temporary bracing

Details

What: Traffic lane reduction at O'Farrell and Stockton due to night work
Time: 9p.m. to 5a.m.
When: Monday to Friday
Where: South side of the Stockton and O'Farrell intersection

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

  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
    • Stockton Street between Ellis Street and Geary Street is closed to vehicular traffic
    • One traffic lane open on O'Farrell through Stockton Street

The cross-cut cavern under the Stockton and Washington intersection has now been opened up and backfilled to prepare for drilling work. 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 cross-cut cavern and headhouse, and excavation and construction of the north access (emergency egress) shaft and tunnel.  The contractor has begun barrel vault preparation work to allow for eventual station cavern excavation.

Soil is lowered from the surface to be used in temporary backfilling work inside the station headhouse. A dump truck delivers soil which will be used to backfill a portion of the cross-cut cavern. Overview

  • Excavation of station site
  • North access (emergency egress) shaft work

Details

What: Excavation of station site
Time: 24 hours
When: Monday to Saturday
Where: Stockton Street and Washington Street

What: North access (emergency egress) shaft work
Time: 7a.m.- 5p.m.
When: Monday to Friday
Where: Stockton Street, Washington Street to Jackson Street What to expect

  • Sidewalk access may be limited at times
  • 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

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 and check out our blog.

Construction schedules are subject to change.