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. 
Drilling equipment is brought into place as part of top heading excavation work for the south platform cavern of Chinatown Station. Central Subway | Project Advancement
May 12 through May 21, 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
An excavator operator sorts concrete removed from the roadway at the approach to the tunnel portal, at 4th and Bryant. 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 water line and fire hydrant construction activity at that intersection. The temporary detour is currently scheduled to extend through May. 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. 
Workers disassemble sections of hose used to pump concrete into the northbound tunnel as part of invert construction. 
Workers at 4th and welsh conduct trenching and utility installation work. 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
- Track installation at tunnel portal
- Temporary bus stop relocation at Bryant and 4th
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: Track installation at tunnel portal
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 worker wrestles with a large diameter hose used to pump concrete into the twin subway tunnels, using the YBM site's proximity to the pour area, in the tunnels just to the south. 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.
Excavation and installation of temporary bracing in both the station box and headhouse is complete. Night work to excavate utilities may occur at 4th and Howard between 9 pm and 5 am. The current traffic configuration from north of the station to Howard Street will remain, but may change in the coming weeks.
Crews install rebar as part of headhouse invert construction. 
The rebar cage for the last section of station box invert slab has been constructed. Overview
- Installation of headhouse and station interior structural elements
- Roadway and sidewalk restoration on 4th south of Howard
- Utility potholing at 4th and Howard
Details
What: Installation of headhouse and station interior structural elements
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: Utility potholing at 4th and Howard
Time: 9 p.m. - 5 a.m.
When: Monday to Friday
Where: 4th and Howard intersection 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
- Muni Impact
- No scheduled impacts at this time
- No scheduled impacts at this time
Looking north from where the south concourse meets the station box, workers are grading the incline where future stairs and escalators will be constructed. 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.
Potential nighttime closure of Ellis between Powell and Stockton to vehicular traffic may be in effect from 9 pm to 5 am 7 days a week, to conduct roadway restoration work. 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. Station excavation and installation of structural steel bracing is ongoing under Stockton Street as well as on O'Farrell.
Sections of precast tunnel lining segments removed from the north end of the station box are stacked for sorting. 
Carpenters construct concrete forms and structural elements at the north station entrance site at Union Square. Overview
- Utility work at the Ellis and Stockton intersection
- Utility work at the Geary and Stockton intersection
- Station excavation and installation of temporary bracing
- Union Square Garage plaza level concrete and structural installation
- Union Square Garage plaza temporary bracing installation
- Nighttime closure of Ellis between Powell and Stockton
Details
What: Nighttime closure of Ellis for roadway restoration work
Time: 9p.m - 5a.m.
When: 7 days a week
Where: Ellis Street between Powell and 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
- Ellis may be closed to vehicular traffic at night between 9 pm and 5 am 7 days a week
- Stockton Street between Ellis Street and Geary Street is closed to vehicular traffic
- Muni Impact
- No scheduled impacts at this time.
A crew adjust drilling equipment as part of top header excavation work for the south platform cavern, just south of and 70 feet below the Washington and Stockton intersection. 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. A pedestrian walkway has now been opened on the north side of Washington between Trenton and Stockton. The contractor completed barrel vault installation mid-November and then began breakout and excavation of the platform cavern side drifts.
The cross-cut cavern has been backfilled halfway to give crews access to the upper portions of the platform cavern. 
Surveyors check their measurements inside the cross-cut cavern under the intersection of Washington and Stockton. 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, 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.