Central Subway Construction Update 2/8/19

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. Looking south inside the Chinatown Station platform cavern, a partially-completed section of platform can be seen with the X-shaped track crossover cavern interchange beyond. Central Subway | Project Advancement

February 8 through February 17, 2019

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 crew fashions sections of mounting brackets for installation against tunnel walls inside the northbound tunnel as it approaches the Market Street S-curve. 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.

Sidewalk and pavement renovation work is underway at 4th and Bryant.  This work may affect vehicular and pedestrian traffic through that part of the intersection.  Construction of the 4th and Brannan surface station platform is ongoing.  Some lane closures may also occur at night.  Regular day shift hours are from 7am to 4pm.  A large section of scaffolding is rolled into place for the installation of metal studs on the platform level of Yerba Buena/Moscone Station. A worker inside the S-curve of the northbound tunnel prepares sections of tunnel wall prior to installing curved brackets to mount utility pipes. Overview

• Night work on 4th Street 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.

A new section of concrete formwork is being built as part of street-level structural elements of the Yerba Buena/Moscone Station headhouse. 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.

Water main replacement work continues at night at 4th and Howard streets.  Work hours are 9 p.m. to 5 a.m.  Eastbound traffic on Folsom may be impacted.  Three through lanes are in place southbound 4th Street. Westbound traffic on Howard Street may be impacted.

Workers on the concourse level install a test piece of a section of the finished concourse ceiling design. Carpenters install rebar and built concrete forms to build an interior wall on the mezzanine level of the headhouse. Overview

• Water main replacement work at 4th and Howard
• Installation of headhouse and station interior elements

Details

What: Water main replacement work
Time: 9pm - 5am
When: Monday to Friday
Where: 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

Two crewmembers on the northbound side of the station platform can be seen painting struts and other interior structural elements, masked off with huge sections of plastic sheeting. 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.

One lane on the south side of Ellis Street is open at all times for eastbound traffic.  Stockton Street between Geary and Ellis is under a long-term closure.  Parking garage access is open on north side of Ellis Street.  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.

A technician walks aisles of systems and electrical equipment being installed inside the north concourse. Steel framing, sections of floor slabs, and and interior cinderblock walls continue to be installed near the south end of the station box. Overview

• 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.

Rebar and formwork are being placed to construct the northern third of the Chinatown Station platform, just north of the intersection of Stockton and Washington. Chinatown Station The construction of Chinatown Station used the sequential excavation method (SEM), providing a high degree of flexibility and control over 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.  Excavation of the Chinatown Station site was completed in February 2018.

The sidewalk along the west side of Stockton between Washington and mid-block toward Clay has temporarily been closed to facilitate utility upgrade work.  Current activities include construction of the north and south platform caverns, cross-cut cavern, track crossover cavern, and interior structural elements of the station headhouse.  A pedestrian walkway is open on the north side of Washington connecting Trenton and Stockton.  Work to build the north egress shaft on Stockton south of Jackson is underway. Pedestrians walk down the temporary walkway along the edge of the headhouse worksite which may be closed again in the coming weeks. Recesses in the concourse level floor slab inside the headhouse mark the eventual landing spots for escalators. Overview

• Construction of structural elements inside the station headhouse
• Construction of stem walls and track slabs for Platform Cavern
• Construction of North Emergency Egress Shaft on Stockton Street

Details

What: Headhouse structural elements, stem walls, track slabs, north emergency egress shaft, and utility vault upgrades
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
  • Stockton Street:
    • sidewalk is open on the west side between Washington Street mid-block toward Clay
  • 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.