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Central Subway Project Update: April 12, 2019

Neighborhoods Affected
Chinatown
South of Market (SoMa)

A worker cuts steel rods as part of 4th and Brannan Station platform ramp construction

Central Subway | Project Advancement

April 12 through April 26, 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.

The 30 & 45 Return to Lower Stockton and 4th Streets

The inbound 30 Stockton and the 45 Union/Stockton are returning to their previous routing on lower Stockton and 4th streets beginning Saturday, April 13. The 30/45 lines were rerouted approximately seven years ago to use Sutter, Mason and 5th streets to make space for Central Subway construction near Union Square. As we near completions of construction in that area, the buses are returning.

For more information and a map see SFMTA.com/LowerStockton

Special Work Notice on 4th Street at Bryant

Repaving work at the intersection of 4th and Bryant streets is currently scheduled to start on Wednesday, April 17. This work will begin at 7 a.m. and will continue 24 hours a day through Sunday, April 21. Temporary lane closures and detours may be in effect during the duration of this work, including at the eastbound I-80 freeway offramp.

Work to repave the 4th and Bryant intersection begins this Wednesday morning

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. 

Crews have continued installing utility conduits and lighting in the northbound tunnel

Rail segments, rebar for track foundations, and sections of tunnel walkway are being added to the southbound tunnel.

Overview

  • 4th and Bryant repaving work
  • Street and sidewalk restoration

Details

What: 4th and Bryant repaving work
Time: 24 hours
When: 7 am, April 17th to Sunday, April 21st
Where: 4th Street at Bryant
What: Road slab reconstruction and street repaving

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 temporary lane closures at and approaching the 4th and Bryant intersection.
    • 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 worker rolls his tool kit across Clementina Alley, adjacent to the Yerba Buena/Moscone Station worksite.  Clementina was recently reopened through between 5th and 4th Street.

Yerba Buena | Moscone Station

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.

Massive ventilation fans are being installed inside the upper level of the station box under 4th street.

Utility conduits and other interior elements continue to be installed inside all three levels of the station box.

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

A shower of sparks fall from a massive streel strut being prepared for painting work at the south end of the Union Square/Market Street Station.

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.

Stockton Street has been reopened to both traffic and transit between Geary and Ellis. This allows the 8, 8AX, 8BX, 30, 45, and 91 OWL bus routes to return to their previous alignments.  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.

The installation of waterproofing, structural elements, 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.

Workers have begun to pour concrete for an intermediate layer of the concourse floor slab, prior to installing the finished terrazzo.

A worker fashions a conduit mounting bracket on the concourse level of the station, near a crew installing utilities in the ceiling

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
    • No impacts expected
  • Muni Impact
    • The 8, 8AX, 8BX, 30, 45, and 91 OWL bus routes have returned to their previous alignments outbound on Stockton Street south of Geary.

A carpenter hands off a specific piece of concrete formwork to an associate at the south end of the Chinatown Station platform cavern.

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.

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.  The sidewalk along the west side of Stockton between Washington and mid-block toward Clay has temporarily been closed to facilitate utility upgrade work.  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.

A welder alters steel plates next to a prep area for lifting sections of formwork to and from the surface inside the headhouse.

Steel framing, railings, and corrugated floor panels have been installed inside the north egress shaft.

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

  • A portion of the sidewalk along the west side of Stockton adjacent to the Chinatown Station worksite has temporarily been closed south of Washington to facilitate utility upgrade work.
  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
    • No parking on both sides of Stockton Street between Washington Street andJackson 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.

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 onFacebook, Twitter, or Flickr.

Construction schedules are subject to change.