Central Subway Construction Update 8/5/16

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.

View looking up through the main access shaft at the Chinatown Station site.

Central Subway | Project Advancement

August 5, 2016 - August 14, 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 restore the roadway following utility upgrades at Bluxome Alley.

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.

Installation of utilities continues along 4th Street between Bryant to Townsend.  A traffic detour for the installation sewer lines on the east side of 4th at Freelon continues.  The tunnel concrete invert is being constructed.  Water line cut-over work taking place in the next week may disrupt service.  Regular day shift hours for other work at STS are 7am to 4pm.

  

As work progresses, equipment is staged for trench excavation. Concrete is smoothed as workers complete a new section of utility work.

Overview

• Sewer installation and traffic detour at Freelon
• Installation of Muni manhole and duct bank
• Utility installation
• Installation of 36" and 48" sewer lines
• Relocation of communication lines
• Water Line cut-over and service disruption

Details

What: Sewer installation work and traffic detour
Time: 7a.m. - 4p.m.
When: Monday to Friday
Where: 4th Street at Freelon

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

What: Installation of 36" and 48" sewer lines
Time:  7a.m. - 4p.m.
When: Monday to Friday
Where: 4th Street between Bryant Street and Townsend Street (east side)

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

What: Public Utilities Commission Water Line cut-and-cap work and service disruption
Time:  11p.m. – 6a.m.
When: Upcoming week
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
  • A detour is in effect for access to Freelon Alley from 4th Street
  • 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

Sheets of waterproofing material line the walls of the station site.

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 installation of utilities on 4th near Howard is ongoing. The current traffic configuration from north of the station to Howard Street will remain.  Excavation and temporary support strut installation continue below concourse level.

Workers conduct soil tests inside the station. A trench is filled following water line installation.

Overview

• Excavation of the headhouse and station box
• Water line replacement and sewer installation

Details

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

A photo shot from the south concourse of the Union Square/Market Street station box.

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.

Night work to install utilities on Geary is has begun and may alter the traffic configuration on Geary.  Night work at the Stockton and O'Farrell intersection will reduce O'Farrell to one lane through the work area.  Jet-grouting work is completed and compensation grouting continues. Current activities include station excavation and installation of temporary bracing under Stockton Street.

Concrete forms are being constructed for the north station entrance at Geary and Stockton.

Excavation work has begun in preparation for station access construction.

Overview

• Roof deck and concrete installation
• Compensation grouting
• Restoration of the southeast corner of the Union Square Garage
• Night work to install utilities at Geary and Stockton
• Traffic lane reduction at O'Farrell and Stockton due to night work

Details

What: Roof deck and concrete installation, rebar installation, utility work, excavation, and partial demolition of Union Square Garage
Time: 7a.m.- 11p.m.
When: Monday to Saturday
Where: Ellis Street to Post Street

What: Compensation grouting
Time: 6a.m - 4p.m. (Monday to Friday) and 6a.m - 2p.m. (Saturday)
When: Monday to Saturday
Where: Geary Street to O'Farrell Street

What: Restoration of the southeast corner of the Union Square Garage
Time: 6a.m - 4p.m. (Monday to Friday) and 6a.m - 2p.m. (Saturday)
When: Monday to Saturday
Where: Geary Street and Stockton Street

What: Night work to install utilities at Geary and Stockton
Time: 9p.m. to 5a.m.
When: Monday to Saturday
Where: Southeast corner of Geary and Stockton intersection

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

Construction crews work on the north access shaft in Chinatown.

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 headhouse, construction of the north access (emergency exit) shaft and tunnel, and construction of the Cross Cut Cavern.

Work continues at the bottom of the headhouse, or station entrance structure.

A carpenter assembles concrete forms inside the station headhouse.

Overview

• Excavation of station site
• North access (emergency exit) 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 exit) 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.

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.