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 man walks atop the five-foot-thick rebar cage of the Union Square/Market Street Station invert slab, as workers install rebar and utility conduits below. Central Subway | Project Advancement
July 21 through July 30, 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
A rail welding machine is pulled out of the way after two more sections of rail are joined together in the median work area at 4th at Bluxome. 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.
Track welding work is also underway along the surface alignment. Repaving work at 4th and Townsend streets may affect traffic patterns. Two southbound lanes of 4th Street are now open between Bryant and Townsend, on either side of the street. 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. 
Sewer tie-in work is underway at 4th and Welsh. 
480-foot sections of rail are organized on 4th at Freelon. 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
- Repaving work at 4th and Townsend streets may affect traffic patterns.
- Partial lane closures on 4th Street between Townsend and King streets.
- 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
Waterproofing membranes and rebar cages are going up inside the station headhouse. 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 involves construction of a box frame structure within a trench excavation that is subsequently backfilled.
Utility work at 4th and Folsom is ongoing and may reduce 4th Street to one lane between the hours of 8 pm and 5 am, Monday through Friday. Sheet pile installation work may occur at 4th and Folsom at night. Night work on Folsom and 4th is permitted from 8pm to 5am Monday through Friday and will have a two month duration.
Night work to excavate and inspect 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.
A carpenter fashions concrete forms inside the station headhouse, at 4th and Folsom. 
Corrugated steel sheet piles have been installed as part of emergency exit construction. 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
Welders affix large pieces of steel I-beams to the east wall of the station box, as part of invert construction work. 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.
A worker at the bottom of the station box receives the large steel box used to lift excavated material to the surface. 
Ventilation systems and other utilities are being installed inside the north station entrance adjacent to the Union Square Garage. 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.
An excavator works away at the invert of the right side drift for the south platform cavern. 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 is open on the north side of Washington connecting Trenton and Stockton.
Excavated material is carried from the bottom of the station headhouse by a large steel box to the surface, where it is sorted and hauled away. 
A bulldozer dumps a bucket full of excavated soil into the steel box used to remove material to the surface of the work site. 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.
Construction schedules are subject to change.