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. 
Potholing to locate utilities is being performed on the north side of 4th and Brannan streets Central Subway | Project Advancement
August 28 - September 7, 2015
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
Trenching and utility upgrades are ongoing on 4th Street Surface Station, Trackwork and Systems For the work along 4th Street between Bryant and King streets, a surface station located between Bryant and Brannan Streets will be built. Besides construction of the surface station, the only visible construction activities will be upgrading utilities and trackwork on 4th Street between the portal at Bryant and the connection with the existing system at King Street.
Take note: Major construction activities will occur at the 4th and King streets intersection, replacing existing tracks and switches for the T Third Line. This is a two-phased project. The first phase of construction is scheduled for Labor Day weekend 10p.m. Friday, September 4 through 5a.m. Tuesday, September 8. The second phase will be performed in early 2016.
To prepare for this activity, the contractor will be sawcutting the pavement from 12:00a.m. to 5.a.m. Friday, September 4. From 10:00p.m. Friday, September 4 to 5 a.m. September 5, the contractor will be potholing. Construction will be very noisy during these activities.
The Labor Day weekend construction will impact residents, merchants, motorists, pedestrians and bicyclists. For more information, please see this notice and map.
Current activities include utilities relocation, Muni manhole and duct bank installation.
Installation of domestic and high pressure water lines on 4th street between Bryant and Freelon streets is ongoing. 
An excavator operator removes soil during trenching operations on 4th Street south of Welsh
Work to install and upgrade waterlines is ongoing at 4th and King Overview
- Installation of Muni manhole and duct bank
- Utility installation
- Installation of domestic and high pressure water lines
- Sawcutting into pavement
- Potholing
- Installation of trackwork and transit signal upgrades
Details
What: Installation of Muni manhole, duct bank, utility installation and installation of domestic and high pressure water line
Time: 7a.m.-4p.m.
When: Monday to Friday
Where: Bryant to Welsh, Brannan between 4th and 5th, Bryant and Freelon
What: Sawcutting into pavement
Time: 12a.m.-5a.m.
When: Friday, September 4
Where: Intersection of 4th and King
What: Potholing
Time: 10p.m. -6 a.m.
When: Friday, September 4 to Saturday September 5
Where: Intersection of 4th and King
What: Installation of trackwork and transit signal priority upgrades
Time: 10p.m. Friday to 5a.m. Tuesday (24 hour operation)
When: Friday,September 4 to Tuesday, September 8
Where: Intersection of the 4th and King
What to expect
- Work may involve saw-cutting, potholing and jack-hammering on the roadway and sidewalk
- Sidewalk access may be limited
- The contractor will maintain a safe path of travel as well as access to businesses during business hours
- Parking and Traffic Impact
- Parking will be unavailable along the work area
- Two lanes on 4th Street between Bryant and King streets are available for traffic
- During the Labor Day weekend construction,southeast section of the 4th and King intersection will be closed to motorists. Delays are expected in this area. Motorists exiting the 4th Street off-ramp will be detoured to 5th and Berry. No left turn permitted from Westbound King to Berry.
Scaffolding to be used to access the headhouse interior is being constructed Yerba Buena | Moscone Station
4th Street from Howard to Folsom
Work along 4th Street between Howard and Folsom streets 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.
Current activities include utility relocation and excavation.
New utilities installed following the backfilling of the last section of roof slab on 4th Street 
Workers begin construction of the stairwell to be adjacent to the station entrance plaza. Overview
- Installation of utilities
- Excavation
Details
What: Utility night work
Time: Folsom Street work begins at 9p.m.-5 a.m, Howard Street work begins 6p.m.-5a.m.
When: Monday to Friday
Where: 4th and Folsom and 4th and Howard
What: Excavation
Time: 7a.m.-7p.m.
When: Monday to Friday
Where: Howard to Folsom
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
- One lane will be available on the west side of 4th Street
- Two right lanes on Folsom Street available during night work
These shipping containers are equipped to support jet grouting in the south concourse Union Square | Market Street Station
For the duration of the project, you'll see work along Stockton Street between Ellis and Post streets. 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 involves construction of a box frame structure within a trench excavation that is subsequently backfilled.
Current activities include roof deck installation, demolition of the northwest corner of the Union Square Garage, utility relocation, compensation, and jet grouting.
Single-lane traffic continues through early October on Geary at Stockton for pile installation.
Walls being constructed from the top down 
A welder on the north side of Ellis connects short I-Beam sections to structural piles ahead of the floor slab construction Overview
- Installation of roof deck
- Utility relocation and support
- Excavation
- Compensation and jet grouting
- Partial demolition of Union Square Garage
- Rebar installation
Details
What: Roof deck, utility, excavation, compensation and jet grouting, rebar installation and partial demolition of Union Square Garage
Time: 7a.m.-11p.m.
When: Monday to Saturday
Where: Ellis to Post
* 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
- Muni Service Impact
- The bus stop for the 38 Geary Route on Geary Boulevard at Stockton Street is discontinued until further notice. Board bus on Geary Boulevard at Powell Street.
- Parking and Traffic Impact
- Ellis Street is closed to through traffic between Stockton and mid-block until late September
- Stockton Street between Ellis and Post streets is closed to vehicular traffic
A large diameter ventilation fan helps provide clean air for workers underneath the roof slab Chinatown Station The construction of an underground Chinatown Station uses the sequential excavation method (SEM) along Washington and Stockton Streets. 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, and dewatering wells.
Dewatering wells installation on Stockton Street from Sacramento to Jackson streets continues through October. 
Work to remove soil involves a bulldozer and a mini excavator working with a large excavator on the surface 
Light flashes and sparks fly with welding and torch cutting on top of the roof slab Overview
- Excavation of station site
- Installation of dewatering wells
- Drilling of compensation grout holes from inside the headhouse
- Relocation of existing utilities
- Installation of instrumentation monitoring units
Details
What: Excavation of station site and drilling compensation grout
Time: 7a.m.- 7p.m.
When: Monday to Saturday
Where: Stockton and Washington
What: Dewatering wells installation
Time: 9p.m.- 5a.m.
When: Monday to Friday
Where: Washington to Jackson
What: Relocation of existing utilities
Time: 7a.m -7p.m.
When: Monday to Friday
Where: Stockton, Washington to Jackson
What: Installation of instrumentation monitoring units
Time: 9p.m.-5a.m.
When: Monday to Saturday
Where: Stockton, Sacramento to Jackson
What to expect
- Sidewalk access may be limited at times
- Parking and Traffic Impact
- Detour will be in place between the hours of 9p.m. to 5a.m. during dewatering wells installation
- Parking will be unavailable during PG&E work
- Washington Street:
- remains closed between Stockton and Trenton streets
- 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.