UPDATE: Incident #NJudah train has been placed onto the sidetrack. Delay at Church and Duboce has cleared. OB https://t.co/vSxfPFyn2C (More: 40 in last 24 hours)

Central Subway Construction Update 9/18/15

Friday, September 18, 2015 - 12:00am

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. Telescopic boom of a concrete pump used at the southeast corner of the Union Square Garage Central Subway | Project Advancement

September 18 - September 28, 2015

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

Trenching for utilities and system items is being performed on the west side 4th Street Surface Station, Trackwork and Systems For the work along 4th Street between Bryant and King streets, a surface station located between Bryant and Brannan Streets will be built. Besides construction of the surface station, the only visible construction activities will be upgrading utilities and trackwork on 4th Street between the portal at Bryant and the connection with the existing system at King Street.

Current activities include utilities relocation, Muni manhole, duct bank, water line work from the water department and auxiliary water supply system tunnel prep work.  Sewer pipes are stacked just south of Townsend on 4th, ready to be installed
  A portion of the new tracks that were installed at 4th and King over Labor Day Weekend Overview

  • Installation of Muni manhole and duct bank
  • Utility installation
  • Installation of High pressure water line
  • Interior tunnel preparation


What: Installation of Muni manhole, duct bank, utility installation
Time: 7a.m. - 4p.m.
When: Monday to Friday
Where: Brannan Street between 4th and 5th, Townsend to King

What:  Low pressure water line/AWSS
Time:  7a.m. - 4p.m.
When:  Monday to Friday
Where:  4th and Welsh

What:  Tunnel interior preparation work
Time:  7a.m. - 4p.m.
When:  Monday to Friday
Where:  Tunnel portal north of the 4th and Bryant intersection

  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
    • Parking will be unavailable along the work area

Work to install utilities and backfill a portion of the station site on Clementina Alley is ongoing Yerba Buena | Moscone Station

4th Street from Howard to Folsom

Work along 4th Street between Howard and Folsom streets 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.

Take note:  Howard Street between 3rd and 4th Street is closed until Sunday, September 20 at 3:00p.m. due to the Dreamforce event at the Moscone Center.  On both 3rd and 4th streets, one lane of traffic will be closed during this time.

Current activities include utility relocation and excavation.

An excavator is used to lift materials from the headhouse and station interior.  This material is then loaded onto dump trucks waiting on nearby Folsom With station roof work mostly complete, two lanes have been reopened for traffic on 4th St. between Howard and Folsom Overview

  • Installation of utilities
  • Excavation


What: Installation of Utilities
Time: 9a.m. - 5p.m
When: Monday to Friday
Where: 4th and Folsom

What: Excavation
Time:  7a.m.-7p.m.
When:  Monday to Friday
Where: Howard to Folsom
  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 the east side of 4th street
    • Howard Street between 3rd and 4th Streets closed through 3p.m. September 20.  This includes one traffic lane on both 3rd and 4th Streets

Excavation and roof construction is underway at the north side of Geary Union Square | Market Street Station

For the duration of the project, you'll see work along Stockton Street between Ellis and Post streets. 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 involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

Current activities include roof deck installation, demolition of the northwest corner of the Union Square Garage, utility relocation, compensation, and jet grouting.

There is an anticipated closure of the Geary and Stockton intersection beginning the weekend of September 18 and continuing through the early part of the week of September 21.  

Single-lane traffic continues through early October on Geary at Stockton for pile installation.

A metal worker grinds the edges of reinforcing beams during the installation of the station roof on Stockton, north of O'Farrell Corrugated steel panels are being installed as part of the south concourse roof construction at Ellis and Stockton Overview

  • Installation of roof deck
  • Utility relocation and support
  • Excavation
  • Compensation and jet grouting
  • Partial demolition of Union Square Garage
  • Rebar installation


What: Roof deck, utility, excavation, compensation and jet grouting, rebar installation and partial demolition of Union Square Garage
Time: 7a.m.-11p.m.
When: Monday to Saturday
Where: Ellis to Post
* Construction hours may be 24 hours a day, Monday to Saturday, Sunday work may be required What to expect

  • Local deliveries may access Maiden Lane from Post Street
  • Sidewalk access may be limited at times
  • Muni Service Impact
    • The bus stop for the 38 Geary Route on Geary Boulevard at Stockton Street is discontinued until further notice. Board bus on Geary Boulevard at Powell Street.
    • The anticipated night closure of the Geary and Stockton intersection will affect 38 and 38R Muni bus stops. 
    • Passengers who board at Geary and Kearny will be redirected to the Market and Montgomery stop.  
    • Passengers for the Geary and Powell stop will be redirected to Geary and Taylor stop.
  • Parking and Traffic Impact
    • Ellis Street is closed to through traffic between Stockton and mid-block until late September
    • Stockton Street between Ellis and Post streets are closed to vehicular traffic
    • Geary and Stockton intersection night closure is anticipated from the weekend of September 18 through Wednesday, September 23

View of the main access shaft showing excavation and soil improvement at the headhouse Chinatown Station The construction of an underground Chinatown Station uses the sequential excavation method (SEM) along Washington and Stockton Streets. 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 immediately after exposure, followed by installation of additional steel and shotcrete support elements until a safe stable opening is created will be used.

Current activities include utility relocation, excavation of the headhouse, and dewatering wells.

Dewatering wells installation on Stockton Street from Sacramento to Jackson streets continues through October. A worker pauses while a portion of the drill shaft is added to the machine A drill rig used to help waterproof the exterior walls of the station headhouse Overview

  • Excavation of station site
  • Installation of dewatering wells
  • Drilling of compensation grout holes from inside the headhouse
  • Relocation of existing utilities
  • Installation of instrumentation monitoring units


What: Excavation of station site and drilling compensation grout
Time: 7a.m.- 7p.m.
When: Monday to Saturday
Where: Stockton and Washington

What: Dewatering wells installation
Time: 9p.m.- 5a.m.
When: Monday to Friday
Where: Washington to Jackson

What:  Relocation of existing utilities
Time:  7a.m -7p.m.
When: Monday to Friday
Where: Stockton, Washington to Jackson

What: Installation of instrumentation monitoring units
Time:  9p.m.-5a.m.
When: Monday to Saturday
Where: Stockton, Sacramento to Jackson

  What to expect

  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
    • Detour will be in place between the hours of 9p.m. to 5a.m. during dewatering wells installation
    • Parking will be unavailable during PG&E work
    • Washington Street:
      • remains closed between Stockton and Trenton streets
      • 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 call us 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.