Central Subway Construction Update 10/13/17

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. A bulldozer and two excavators are among many pieces of equipment utilized during excavation of the northern portion of the Chinatown station platform cavern. Central Subway | Project Advancement

October 13 through October 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

A worker sprays water to help keep dust down in the worksite, following soil grading along 4th Street between Townsend and King. 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.

Sewer and water line, and track work are underway on 4th between Bryant and King Streets, and night work is ongoing between 8:00 PM and 5:00 AM.  Some lane closures may also occur at night.  Regular day shift hours are from 7am to 4pm.  Haze from the massive fires in the north bay partially obscures buildings in the distance, looking south down 4th Street from Bryant. Two men carry equipment and supplies in and out of the tunnel portal worksite on 4th Street just north of Bryant. Overview

• Night work on 4th between King and Bryant
• Street and sidewalk restoration
• Temporary bus stop relocation at Bryant and 4th
• Utility upgrade and relocation

Details

What: Night utility work on 4th 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 and street restoration work

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

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.
  • Parking will be unavailable in the work area on both sides of 4th Street.
  • Two lanes of traffic open on 4th Street, one on the east side and one on the west.
  • Traffic impacts are in effect 24 hours a day.
• Muni Impact
  • No scheduled impacts at this time

A crew pours concrete around future elevator footings inside the station box, as part of construction for the Yerba Buena/Moscone Station platform. 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 involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

Sewer and water supply infrastructure replacement work continues at 4th and Folsom streets, Monday through Friday, from 9 p.m. to 6 a.m. During these work hours southbound 4th Street will be reduced to one lane and eastbound Folsom Street will be reduced to two lanes.  The right hand turn lane will be affected.  Two through lanes are in place southbound 4th Street. Westbound traffic on Howard Street will be impacted.

Sewer replacement work continues at night at 4th and Howard streets until early to mid-October. Work hours are 8 p.m. to 5 a.m.  The current traffic configuration from north of the station to Howard Street will remain, but may change in the coming weeks.

Workers clean up around rebar along the west slurry wall of the headhouse, following a recent concrete pour for the concourse level floor slab. Two men keep the worksite tidy atop the recently-compelted concourse level floor slab inside the headhouse. Overview

• Sewer replacement work
• Night work at Folsom and 4th.
• Installation of headhouse and station interior structural elements
• Roadway and sidewalk restoration on 4th south of Howard
• Utility potholing at 4th and Howard

Details

What: Sewer replacement work
Time: 7am - 3pm
When: Monday to Friday
Where: 4th and Howard Street intersection.

What: Night work at Folsom and 4th
Time:  8pm - 5am
When: Monday to Friday
Where: Folsom Street west of the intersection at 4th, and at the 4th Street intersection.

What: Installation of headhouse and station interior structural elements
Time:  7am - 7pm
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:  7am - 4pm
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street

What: Utility potholing at 4th and Howard
Time: 9pm - 5am
When: Monday to Friday
Where: 4th and Howard intersection

What: Curb installation work
Time: 7am - 7pm
When: Monday to Saturday
Where: Clementina between 4th and 5th What to expect

• Clementina Street is closed for traffic and pedestrians through to 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, may be reduced to one lane at night between 9 pm and 5 am Monday through Friday.
• Muni Impact
  • No scheduled impacts at this time

Workers install rebar, utilities, and vinyl sheeting for waterproofing inside the north concourse's lower level, where it turns to meet the north station entrance at Union Square. 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.

Potential nighttime closure of Ellis between Powell and Stockton to vehicular traffic may be in effect from 9 pm to 5 am 7 days a week, to conduct roadway restoration work.  The installation of waterproofing, structural steel, and concrete at the southeast corner of the Union Square Garage continues.  There will be a continued presence of vehicles and equipment as work at this location continues.  Station excavation and installation of structural steel bracing is ongoing under Stockton Street as well as on O'Farrell.

Workers use boom lifts to install temporary bracing and formwork for internal structural elements in the station box. Crews are hard at work constructing the rebar cage for the invert slab of the north concourse's lower level. Overview

• Utility work at the Ellis and Stockton intersection
• Utility work at the Geary and Stockton intersection
• Station excavation and installation of temporary bracing
• Union Square Garage plaza level concrete and structural installation
• Union Square Garage plaza temporary bracing installation
• Partial closure of Ellis between Powell and Stockton

Details

What: Partial closure of Ellis for roadway restoration work
Time: 7 am to 8 pm.
When: 7 days a week
Where: Ellis Street between Powell and Stockton

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
  • Ellis may be closed to vehicular traffic at night between 9 pm and 5 am 7 days a week for roadway and sidewalk restoration work
  • Stockton Street between Ellis Street and Geary Street is closed to vehicular traffic
• Muni Impact
  • No scheduled impacts at this time.

The arm of an excavator fitted with a rock grinder works away at the invert of the Chinatown Station north platform cavern's center drift. 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.  A pedestrian walkway is open on the north side of Washington connecting Trenton and Stockton.

A man carefully maneuvers a boom lift down the south platform cavern for Chinatown Station. A worker tests pressure on a spraying device used in soil improvement work. 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
• 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, except to pedestrians
    • 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.