UPDATE: Incident #NJudah train has been placed onto the sidetrack. Delay at Church and Duboce has cleared. OB https://t.co/vSxfPFyn2C (More: 41 in last 24 hours)

Central Subway Construction Update 9/25/15

Friday, September 25, 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. Excavation and upgrading of a waterline at 4th Street and Freelon Alley Central Subway | Project Advancement

September 25 - October 5, 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

Muni light rail vehicles are enjoying the new trackwork at 4th and King Surface Station, Trackwork and Systems For the work along 4th Street between Bryant and King streets, a surface station will be built between Bryant and Brannan Streets. The construction team is working on upgrading utilities and trackwork on 4th Street between the portal at Bryant Street and the connection with the existing system at King Street.

Please note, excavation to find underground utilities will be performed from Saturday, September 26  at 7a.m. to Sunday, September 27 at 5a.m at the intersection of 4th Street and Townsend Street.  This work will include cutting into the pavement, so construction may be noisy at times.

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
  Trenching for utilities and systems is being done on  the west side of 4th Street between Bryant and Brannan Overview

  • Installation of Muni manhole and duct bank
  • Utility installation
  • Installation of High pressure water line
  • Interior tunnel preparation
  • Excavation to install underground utilities


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

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

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:  Excavation to locate underground utilities
Time:   7a.m. to 5a.m.
When:  Saturday, September 26th through Sunday, September 27th

  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 at Clementina Alley is underway 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.

Current activities include utility relocation and excavation.

A bulldozer emerges from the access portal into the station platform to offload material being removed from inside the station Work to excavate the station headhouse is underway at 4th and Clementina Alley Overview

  • Installation of utilities
  • Excavation


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

What: Excavation
Time:  7a.m.-7p.m.
When:  Monday to Friday
Where: Howard  Street to 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 the east side of 4th Street

Construction of the station roof is underway including removal of utilities and soil grading Union Square | Market Street Station

For the duration of the project, you'll see work along Stockton Street between Ellis Street 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.

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

A section of station roof under construction between O'Farrell and Geary on Stockton.  A temporary truss bridge spans this work site, allowing machinery to move to the next section of roof being installed A view from mid-way down the former Ellis Street entrance stairs to Powell/BART Muni station.  This entrance will serve as a primary access point for the south concourse of Union Square|Market Street station 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 Street to Post Street
* 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.
  • Parking and Traffic Impact
    • Ellis Street is closed to through traffic between Stockton and mid-block until mid-October
    • Stockton Street between Ellis Street and Post Street is closed to vehicular traffic 

This drill rig is used to inject a concrete-waterproofing grout solution to prevent future leaks 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 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 Street to Jackson Street continues through October. Water splashes as a drill shaft is removed following drilling A pair of workers screw another section of drill shaft onto the existing section being used to help waterproof the headhouse structure 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 Street and Washington Street

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

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

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

  What to expect

  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
    • Detours will be in place between the hours of 9p.m.and 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.