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. 
Utility work is performed in a trench on 4th Street Central Subway | Project Advancement
April 22, 2016 - May 2, 2016
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
Workers backfill a trench on 4th Street near Freelon Street 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.
Current activities include utilities relocation, Muni manhole, duct bank, water line work from the water department, auxiliary water supply system (AWSS) and sewer structure modification work. Night work to install a high pressure water line at the intersection of 4th Street and Townsend Street continues through Friday, May 6. Hours of construction are 7p.m. to 5a.m.
Sewer line installation has begun on the east side of 4th Street
Excavation is performed at 4th Street and Bluxome Street Overview
- Installation of Muni manhole and duct bank
- Utility installation
- Installation of AWSS
- High pressure water line installation
- Installation of 36" and 48" sewer lines
Details
What: Installation of Muni manhole, duct bank, utility installation
Time: 7a.m.- 4p.m.
When: Monday to Friday
Where: 4th Street and Freelon Street
What: Installation of AWSS
Time: 7a.m.- 4p.m.
When: Monday to Friday
Where: 4th Street between Brannan Street and Townsend Street and 4th Street between Brannan Street and Bluxome Street
What: High pressure waterline installation (night work)
Time: 7p.m - 5a.m.
When: Monday to Friday
Where: 4th Street and Townsend Street
What: Installation of 36" and 48" sewer lines
Time: 7a.m. - 4p.m.
When: Monday to Friday
Where: 4th Street between Bryant Street and King Street (east side) 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
- 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
Workers build wooden forms in the mezzanine level to prepare for concrete pouring 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 is ongoing in the station box, mezzanine and headhouse. Utility work is being performed on the east side of 4th Street.Traffic shifted on 4th Street between Howard Street and Folsom Street.Two lanes of traffic are open in the center of 4th Street.
Crews install a water line on 4th Street and Howard Street 
Workers construct a rebar cage for the mezzanine floor Overview
- Excavation
- Water line replacement and sewer installation
Details
What: Excavation
Time: 7a.m - 7p.m.
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street
What: Water line replacement and sewer installation
Time: 7a.m.- 4p.m.
When: Monday to Friday
Where: 4th Street between Howard Street and 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 in the center of 4th Street
View of the roof deck at Stockton Street and O'Farrell Street Union Square | Market Street Station
Work continues 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 and involves construction of a box frame structure within a trench excavation that is subsequently backfilled.
Current activities include roof deck installation, demolition of the southeast corner of the Union Square Garage, compensation and jet grouting, and utility relocation.
Demolition of the station box walls in preparation for I-beam installation 
Excavation continues on Stockton Street, near Geary Street Overview
- Roof deck installation
- Concrete installation
- Rebar installation
- Utility relocation and support
- Excavation at north concourse
- Partial demolition and restoration of Union Square Garage
- Compensation grouting
- Jet grouting
Details
What: Roof deck and concrete installation, rebar installation, utility work, excavation, and partial demolition of Union Square Garage
Time: 7a.m.- 11p.m.
When: Monday to Saturday
Where: Ellis Street to Post Street
What: Compensation grouting
Time: 6a.m - 4p.m. (Monday to Friday) and 6a.m - 2p.m. (Saturday)
When: Monday to Saturday
Where: Geary Street to O'Farrell Street
What: Jet grouting
Time: 6a.m - 4p.m. (Monday to Friday) and 6a.m.- 2p.m. (Saturday)
When: Monday to Saturday
Where: Geary Street to Ellis Street
What: Restoration of the southeast corner of the Union Square Garage
Time: 6a.m - 4p.m. (Monday to Friday) and 6a.m - 2p.m. (Saturday)
When: Monday to Saturday
Where: Geary Street and Stockton Street
*For all activities, 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
- Stockton Street between Ellis Street and Post Street is closed to vehicular traffic
- One traffic lane open at Stockton Street and O'Farrell Street
A view of the future entrance archway where jet grouting 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 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, north access (emergency exit) shaft construction. 
A jackhammer is used to prepare for steel beam installation 
Scaffolding has been installed in the headhouse in preparation for grouting
Overview
- Excavation of station site
- North access (emergency exit) shaft
- Sewer slip lining installation
Details
What: Excavation of station site
Time: 24 hours
When: Monday to Saturday
Where: Stockton Street and Washington Street
What: North access (emergency exit) shaft
Time: 7a.m.- 5p.m.
When: Monday to Friday
Where: Stockton Street, Washington Street to Jackson Street
What: Sewer slip lining installation
Time: 7p.m - 5a.m.
When: Monday to Friday
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
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.