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. 
Following the completion of the floor (invert) slab at the Yerba Buena/Moscone Station, the largest elements of temporary bracing have been removed from the platform level. Central Subway | Project Advancement
June 23 through July 2, 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
Crews continue to conduct utility work on the east side of 4th south of 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 the summer months. 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 and street restoration work are underway on 4th Street. 
Light towers for night work are stored inside the worksite along 4th. 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 welder cuts away steel brackets used as part of temporary bracing at the north end of 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.
Starting this week, utility work at 4th and Folsom will reduce 4th Street to one lane between the hours of 8 pm and 5 am, Monday through Friday. Sheet pile installation work may begin at 4th and Folsom at night on Saturday, June 24. A white zone at 821 Folsom Street will be temporarily relocated to 831-833 Folsom Street to facilitate the excavation and construction of stairs for the Yerba Buena/Moscone Station. Night work on Folsom and 4th is permitted from 8pm to 5am Monday through Friday and will have a two month duration.
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.
Rebar cages for columns inside the headhouse are going up. Soon, workers will pour concrete and erect forms for next level's floor. 
A worker drills holes in the concrete slurry wall of the headhouse to install rebar as part of internal structural construction work. Overview
- Night work at Folsom and 4th.
- 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: Night work at Folsom and 4th
Time: 8pm - 5am
When: Monday to Friday
Where: Folsom Street west of the intersection at 4th, and at the 4th Street intersection.
What: Installation of headhouse and station interior structural elements
Time: 7am - 7pm
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: 7am- 4pm
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street
What: Utility potholing at 4th and Howard
Time: 9pm - 5am
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, 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
- No scheduled impacts at this time
Tunnel lining segments have almost entirely removed from the station box under Stockton Street. This view, looking south, shows where the tunnels curve toward 4th Street under Market. 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.
Material excavated from inside the station box is sorted and removed using a large steel bucket, lifted toward the surface for loading onto trucks. 
A backhoe operator helps grade a slope at the top of where escalators and stairs will bring passengers to and from the station platform. 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.
Bulldozers and other excavation machines shuttle back and forth from the south platform cavern area, where excavation is underway. 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. Sewer excavation work on Washington between Stockton and Spofford is scheduled through June. This may affect vehicular access on Washington. Please see details below.
A bulldozer and drilling equipment pause inside the headhouse, while excavated material is lifted to the surface. 
Looking east into the cross-cut cavern, a bulldozer emerges with a bucket full of soil taken from the south platform cavern. Overview
- Excavation of station headhouse
- Excavation of the north and south platform caverns
- Sewer main replacement
Details
What: Station site excavation
Time: 24 hours
When: Monday to Saturday
Where: Stockton Street and Washington Street
What: Sewer main replacement
Time: 7:00 pm to 6:00 am
When: Monday through Saturday
Where: Washington Street between Stockton and Spofford What to expect
- Sidewalk access may be limited at times
- Parking and Traffic Impact
- Sewer main replacement work may require closure of Washington Street between Waverly and Stockton
- 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.