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 crew transfers materials from the headhouse to the station box via the access portal. Central Subway | Project Advancement
February 10 through February 19, 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
New sewer pipes and a high-pressure water line are being installed at 4th and Welsh. 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.
Vehicular access to 4th from Welsh Street will be temporarily detoured, due to sewer construction activity at that intersection. The temporary detour is currently scheduled to extend through March 17. Night work is ongoing on 4th Street between Bryant and King Streets, between 8:00 PM and 5:00 AM. Utility installation and upgrade work continues along 4th Street between Bryant and King, and regular day shift hours are from 7am to 4pm. 
Utility work is ongoing at the 4th and Brannan intersection. 
Street restoration work is active between King and Welsh. Overview
- Night work between King and Bryant
- Sewer improvement work
- Utility installation
- Sewer manhole installation
- Relocation of communication lines
- Construction of tunnel portal transition slab
Details
What: Night utility work 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 work
What: Pavement renovation
Time: 7 a.m. - 5:30 p.m.
When: Monday to Saturday
Where: 4th Street between King and Welsh
What: Installation of manhole structure, duct bank, utility installation
Time: 7 a.m. - 4 p.m.
When Monday to Friday
Where: 4th Street at Brannan
What: Installation of water line, MRY duct bank, utility installation
Time: 7 a.m. - 4 p.m.
When Monday to Friday
Where: 4th Street at Townsend
What: Relocation of communications lines
Time: 7 p.m. - 5 a.m.
When: Monday to Friday
Where: 4th Street at Brannan
What: Construction of tunnel portal transition slab
Time: 7 a.m. - 4 p.m.
When: Monday to Saturday
Where: 4th Street at 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
- Vehicular access to 4th from Welsh Street has been temporarily detoured.
- Partial lane closures on 4th Street between Townsend and King streets.
- Detours will be in place. The crosswalk may be disrupted. Alternative pedestrian walkways will be in place.
- Parking will be unavailable in the work area on both sides of 4th Street.
- Two lanes of traffic open on the west side of 4th Street.
- Traffic impacts are in effect 24 hours a day.
- Muni Impact
- No scheduled impacts at this time.
A massive rebar cage is being assembled one section at a time as part of work to construct the station box's base or "invert" slab. 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.
Night work to excavate utilities may occur at 4th and Folsom between 9 pm and 5 am. Excavation of the Yerba Buena/Moscone Station underneath 4th Street between Folsom and Clementina continues. The current traffic configuration from north of the station to Howard Street will remain, but may change in the coming weeks. Excavation and installation of temporary bracing continues at the station platform level.
Workers assemble the massive invert slab on the platform level of the station box. 
A truck is loaded with excavated material at the curb adjacent to the worksite on Folsom. Overview
- Excavation of the headhouse and station box and installation of temporary bracing
- Roadway and sidewalk restoration on 4th south of Howard
- Night utility work at 4th and Folsom.
Details
What: Excavation of the headhouse and station box and installation of temporary bracing
Time: 7a.m - 7p.m.
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: 7a.m.- 4p.m.
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street
What: Night utility work at 4th and Folsom
Time: 9 pm to 5 am
When: Monday to Friday, until February 4
Where: North side of Folsom adjacent to the work site, west of 4th What to expect
- Clementina Street is closed at 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
- Muni Impact
- No scheduled impacts at this time
- No scheduled impacts at this time
Superfluous rebar and other steel reinforcing are removed from the south headwall, where the future escalators and stairs will lead to and from the future station platform level. 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.
O'Farrell Street at Stockton may be narrowed to one lane at night to allow for the removal of excavated materials. The installation of waterproofing 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 and equipment are able to access the north concourse through a secure gate at the Union Square Garage. 
Looking east down the north side of O'Farrell, where the exterior structure of future emergency egress stairs is being constructed. Overview
- Utility work at the Ellis and Stockton intersection
- Utility work at the Geary and Stockton intersection
- Partial closure of the walkway adjacent to the southeast corner of the Union Square Garage
- Station excavation and installation of temporary bracing
- Union Square Garage plaza level concrete installation
Details
What: Partial closure of the walkway adjacent to the southeast corner of the Union Square Garage
Time: 9 a.m. - 2 p.m. and 8 p.m. - 5 a.m.
When: Through February 18
Where: Temporary sidewalk adjacent to the Union Square Garage work site on the north side of Geary, west of 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
- Stockton Street between Ellis Street and Geary Street is closed to vehicular traffic
- Muni Impact
- No scheduled impacts at this time.
Workers have made tremendous progress excavating the initial outer portions of the north and south platform caverns, called side drifts. 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. The contractor completed barrel vault installation mid-November and then began breakout and excavation of the platform cavern side drifts.
The main access shaft and staff elevator as seen from the surface of the work site. 
Two workers discuss operations at the bottom of the headhouse. 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
- 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.