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Central Subway Construction Update 12/11/15

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.

Holiday shoppers rest on the illuminated benches of the Winter Walk

Central Subway | Project Advancement

December 11 - 21, 2015

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 goes 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

PG&E crews working on the corner of 4th and Bryant, adjacent to the Hotel Utah

Surface Station, Trackwork and Systems For the work along 4th Street between Bryant and King Streets, a surface station will be built between Bryant and Brannan Streets. The construction team is working on upgrading utilities and trackwork on 4th Street between the portal at Bryant Street and the connection with the existing system at King Street.

Current activities include utilities relocation, Muni manhole, duct bank, water line work from the water department, auxiliary water supply system, and sewer structure modification work. A worker uses a small jackhammer to remove concrete from around utilities powering a light pole slated to be replaced once overhead line work is complete
  Work along 4th Street between Townsend Street and King Street is minimal with only a small work area fenced off for the holidays  Overview
 

  • Installation of Muni manhole and duct bank
  • Utility installation
  • Installation of high pressure water lines
  • Tunnel drainage and invert slab construction

Details

What: Installation of Muni manhole, duct bank, utility installation
Time: 7a.m. - 4p.m.
When: Monday to Friday
Where: Brannan Street between 4th Street and 5th Street, Townsend Street to King Street

What:  Low pressure water line/AWSS
Time:  7a.m. - 4p.m.
When:  Monday to Friday
Where:  4th Street between Welsh Street and Brannan Street

What:  Installation of 8" waterline
Time:  9p.m. - 5a.m.
When:  Monday to Friday
Where:  4th Street and  Brannan Street

What:  High pressure waterline
Time:  9p.m. - 5a.m.
When:  Monday to Friday
Where:  4th Street south of Townsend Street

What:  Tunnel drainage and invert slab construction
Time:  7a.m. - 4p.m.
When:  Monday to Friday
Where:  4th Street Tunnel

  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
  • Muni Impact
    • 4th Street and Bryant Street bus stop relocated 250 feet off the intersection affecting 8 Bayshore, 8AX Bayshore Express, 8 BX Bayshore Express and 47 Van Ness bus lines. 
  • Parking and Traffic Impact  
    • Parking will be unavailable in the work area along 4th Street
    • One lane on 4th Street closed during nightwork

Workers sort different lengths and gauges of rebar to be installed inside the station box 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.

Currently, excavation is taking place.
 

Excavation equipment is temporarily stored in the head structure while the mezzanine ceiling slab is being constructed inside the station box. An extra long arm extension added to this large excavator allows an operator to lower the bucket further down into the headhouse to remove material Overview
 

  • Excavation

Details

What: Excavation
Time:  7a.m.-7p.m.
When:  Monday to Friday
Where: Howard  Street to 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 the east side of 4th Street

Utilities are being upgraded and spliced in with other new systems Union Square | Market Street Station

For the duration of the project, you'll see work 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 involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

Throughout the moratorium there will be limited construction in the area. Traffic on Stockton Street between Post and Geary streets will be allowed by the end of December. 

Winter Walk 2015 opened to the public November 27 and runs through January 1.  For more information, click here. 

Exposed utilities formerly suspended above north concourse roof deck construction now rest on concrete pads seen prior to backfilling A woman quietly reads as holiday revelers and shoppers walk across the green turf of the Winter Walk between O'Farrell and Ellis streets Overview

  • Installation of roof deck
  • Utility relocation and support
  • Excavation at north concourse
  • Partial demolition and remodeling of Union Square Garage
  • Rebar installation
  • Lightweight concrete installation as roadway backfill at north and south concourses

Details

What: Roof deck, utility, excavation, rebar installation, partial demolition of Union Square Garage and lightweight concrete installation
Time: 7a.m.-11p.m.
When: Monday to Saturday
Where: Ellis Street to Post Street
* Construction hours may be 24 hours a day, Monday to Saturday, Sunday work may be required What to expect

  • Local deliveries may access Maiden Lane from Post Street
  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
  • Although Ellis Street is reopened to one lane of eastbound traffic, vehicles will not be able to turn onto Market Street as part of the Safer Market Street project.  For more information, please visit https://www.sfmta.com/projects-planning/projects/safer-market-street
  • Stockton Street between Ellis Street and Post Street is closed to vehicular traffic

Crews have begun constructing sections of the final interior structure of the station headhouse 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 immediately after exposure, followed by installation of additional steel and shotcrete support elements until a safe stable opening is created will be used.

Current activities include utility relocation, excavation of the headhouse, trenching and connection of dewatering wells, north access (emergency exit) shaft construction and sewer upgrades.
  Welders fashion brackets for a large strut in the southeast corner of the Chinatown headhouse VA long steel I-beam rests with others at the bottom of the station headhouse.  These beams will be used to reinforce the exterior walls of the headhouse structure Overview

  • Excavation of station site
  • Connection of dewatering wells
  • Installation of temp bracing
  • North access (emergency exit) shaft construction
  • Sewer upgrades

Details

What: Excavation of station site
Time: 7a.m.-7p.m.
When: Monday to Saturday
Where: Stockton Street and Washington Street

What:  Connection of dewatering wells
Time:  7a.m - 5p.m.
When: Monday to Friday
Where: Stockton Street, Sacramento Street to Jackson Street

What:  Installation of temp bracing
Time:  7a.m -5p.m.
When: Monday to Friday
Where: Stockton Street

What:  North access (emergency exit) shaft construction
Time:  7a.m - 5p.m.
When: Monday to Friday
Where: Stockton Street, Washington to Jackson Street

What:  Sewer upgrades
Time:  7p.m - 5a.m.
When: Monday to Friday
Where: Stockton Street, Clay to Washington Street

  What to expect

  • Sidewalk access may be limited at times
  • Parking and Traffic Impact
    • Detours will be in place between the hours of 9p.m.and 5a.m. during north access shaft construction
    • Parking will be unavailable during PG&E work
    • No parking on both sides of Stockton between Washington and Jackson
    • No parking on both sides of Stockton between Clay and Washington during night work
    • Washington Street:
      • remains closed between Stockton and Trenton streets
      • 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 or call us 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, and check out our blog.

Construction schedules are subject to change.