Central Subway Construction Update 3/23/18

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. The Chinatown Station platform cavern and part of the cross-cut cavern entrance from the headhouse can be seen looking south far below the Stockton and Washington intersection. Central Subway | Project Advancement

March 23 through April 1, 2018

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

Mechanics tend to a concrete pump at the top of the tunnel portal during a heavy rain, just north of the intersection at Bryant and 4th. 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.

Construction of the 4th and Brannan surface station platform is ongoing.  Water line replacement work is underway on 4th Street at Brannan, and night work is ongoing between 8:00 PM and 5:00 AM.  Track installation work is ongoing between Brannan and King.  Some lane closures may also occur at night.  Regular day shift hours are from 7am to 4pm.  A worker carefully walks down lengths of rail stored between sections of track already installed in the southbound tunnel. Rain falls in SoMa near a double track crossover between Townsend and Bluxome. Overview

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

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: Street and sidewalk restoration
Time: 7 a.m. - 5:30 p.m.
When: Monday to Saturday
Where: 4th Street between King and Bryant

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.

Various stages of roof deck construction can be seen inside the Yerba Buena/Moscone Station headhouse at 4th and Folsom. 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 replacement work continues at night at 4th and Howard streets. 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. Two through lanes are in place southbound 4th Street. Westbound traffic on Howard Street will be impacted.

Large, complex sections of scaffolding are carefully positioned into place atop the concourse level floor slab inside the station headhouse. The rebar cage at the south end of the station headhouse roof comes together adjacent to scaffolding and concrete form installation work. Overview

• Water line replacement work at 4th and Folsom
• Sewer replacement work at 4th and Howard
• Installation of headhouse and station interior elements

Details

What: Sewer and water line replacement work
Time: 8pm - 5am
When: Monday to Friday
Where: 4th and Folsom and 4th and Howard Street intersections.

What: Installation of headhouse and station interior elements
Time:  5am - 3:30pm
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street 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

On the mezzanine level of the station box looking south, concrete forms are being constructed around the base of an opening for an elevator shaft, as well as other internal walls. 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.

One lane on the south side of Ellis Street is open at all times for eastbound traffic.  Parking garage access is open on north side of Ellis Street. Utility installation and street restoration work are ongoing north of the intersection of Stockton and Market streets.  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.  Installation of internal structural elements and utilities is ongoing under Stockton Street as well as the northeast corner of Stockton and O'Farrell.

Equipment and materials are moved inside the surface worksite north of O'Farrell, near one of the vertical access shafts. New sections of sewer pipe have been placed in a trench along the east side of Stockton between Ellis and O'Farrell. Overview

• Utility work on Stockton north of Ellis
• Utility work at the Geary and Stockton intersection
• Installation of internal structural elements and temporary bracing
• Union Square Garage (north station entrance) structural installation

Details

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
• Muni Impact
  • No scheduled impacts at this time.

Plywood is placed as part of concrete form construction at the south end of the Chinatown Station track crossover cavern. Chinatown Station The construction of 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 construction of the north and south platform caverns, as well as the invert slab of the station headhouse.  A pedestrian walkway is open on the north side of Washington connecting Trenton and Stockton.

A crew lays out huge sheets of plastic sheeting during a rainstorm to reduce mud at the bottom of the Chinatown Station headhouse. Workers adjust cribbing placed for easy movement of equipment and materials across the curved floor of the crossover cavern. Overview

• Construction of the base slab inside the station headhouse
• Construction of the station platform and track crossover cavern interiors

Details

What: Headhouse, platform cavern, and track crossover cavern construction
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.