Construction Update
December 7-16, 2013
We completed an important construction milestone last week as our tunneling contractor and TBM Mom Chung successfully and safely tunneled under Market Street and the existing BART and Muni tunnels. The TBM is now under Stockton Street in Union Square.
During the next 10 days, Central Subway work will continue at sites in SoMa, Union Square, Chinatown and North Beach. This section contains brief updates about what is happening in each neighborhood. For more detailed information, scroll down or click on the links below. We also post construction, traffic detour and Muni impact information on our project Google Map.
Southern SoMa (Harrison to King/Berry): We expect to begin potholing for utilities on 4th Street between Bryant and King the week of Dec. 16. At the tunnel launch box on 4th Street between Harrison and Bryant, tunneling continues with both TBMs.
Northern SoMa (Market to Harrison): We have reestablished our work zone on 4th Street between Folsom and Harrison, in front of Pacific Bicycle. Work here involves improving ground conditions as the second TBM, Big Alma, passes underground. Work is currently paused at 4th and Stevenson, to resume when Big Alma reaches that area. At 4th and Folsom, we are building a covered walkway adjacent to the construction site on 4th Street and Clementina.
Union Square: Construction is now paused on Stockton Street, resuming in January. Work will continue on Ellis Street during December to allow for ground improvements related to tunneling.
Chinatown: Last week our crews closed a portion of Washington Street just west of Stockton Street to allow for utility work and the construction of underground Chinatown Station walls. Tentative: On Clay and Jackson streets adjacent to Stockton Street, the contractor may be performing underground borings some nights next week.
North Beach: Construction is now paused on Columbus Avenue, resuming in January. Work will continue on private property at 1455 Stockton and 1731-1741 Powell to ensure we are ready for the arrival of the first TBM in the spring. One morning next week, heavy equipment will be delivered to the construction site at the 1455 Stockton parking lot early in the morning, before regular working hours.
We appreciate your patience and support while we build this essential upgrade to San Francisco's public transportation system.
-The Central Subway Team 
Beneath 4th Street just south of Harrison, we now have two new tunnels in progress. Southern SoMa
4th Street from Harrison to King/Berry
On 4th Street between Harrison and Bryant streets, the contractor has constructed a major excavation known as a launch box at the site where the Central Subway tunnel begins. After assembly of two tunnel boring machines (TBM) underground, tunneling is underway.
On 4th Street between Bryant and King streets, we plan to begin potholing for utilities the week of Dec. 16. Potholing involves drilling small holes and trenches in the street to confirm the locations of existing utility lines. More information is available in this construction notice.
Planned construction (Harrison to Bryant):
- Construct tunnel for southbound trains (TBM Mom Chung)
- Construct tunnel for northbound trains (TBM Big Alma)
Traffic and pedestrian impacts (Harrison to Bryant):
- The two lanes on the east side of the street (left lanes for southbound traffic) will remain open to vehicle traffic except as described below.
- The block may close to traffic from 8 p.m. to 5:30 a.m. on weeknights and all day Saturday and Sunday.
- The sidewalk on the west side of the block will remain closed; the sidewalk on the east side of the block will remain open.
- On Bryant Street at 5th Street, the left lane and several parking spaces will be closed.
Planned construction (Bryant to King):
- Potholing is planned to start on 4th Street between Bryant and King the week of December 16
- Construction will take place within construction zones marked by cones. Construction zones will move daily as work proceeds.
- Initially, work will take place on the eastern side of 4th Street and the eastern sidewalk.
- Work hours will be Monday to Friday, 7 a.m. to 5 p.m.
Traffic and pedestrian impacts (Bryant to King):
- Starting the week of Dec. 16, temporary partial lane closures may be in effect on 4th Street in the vicinity of construction zones
- Parking will be impacted in the vicinity of construction zones. The contractor will post 72-hour notification as required.
- Sidewalks will be impacted on the eastern side of the street. The contractor will maintain a safe path of travel at all times.
- The contractor will maintain access to all businesses during business hours.
As we prepare to build the Yerba Buena/Moscone Station, we have moved construction equipment, including this crane, onto the site at 4th and Folsom. Northern SoMa
4th Street from Market to Harrison
On 4th Street between Market and Stevenson, construction is currently paused, to resume when the second TBM reaches the area.
On 4th Street between Howard and Folsom, preparatory work to construct the Yerba Buena/Moscone Station is now in progress at the corner of 4th and Folsom. Station construction will start soon.
On 4th Street between Folsom and Harrison, the contractor will perform ground improvements while the second TBM passes beneath the roadway.
Planned construction (Market to Stevenson):
- None planned
Traffic and pedestrian impacts (Market to Stevenson):
- Two lanes of traffic will remain open on the west side of the street, with the work zone on the east side of the street (near Ross)
- The taxi stand has been relocated to Market Street just south of Stevenson.
Planned construction (Howard to Folsom):
- Construct test elements for underground walls
- Construct covered walkway on 4th Street and Clementina, adjacent to construction site
- Planned work hours are Monday to Friday, 7 a.m. to 5 p.m.
- Tentative: Perform underground sewer surveys on Folsom near the intersection with 4th. This work may occur at night.
Traffic and pedestrian impacts (Howard to Folsom):
- The two right lanes of 4th Street will remain closed to traffic
- Clementina between 4th and 5th is closed to thru traffic. Please use this block for local access only.
- The sidewalk on the west side of 4th Street between Clementina and Folsom will be closed. To ensure pedestrian safety, please use the sidewalk on the east side of the street and cross at 4th and Howard.
- Big trucks will enter and exit the 4th and Folsom site during work hours. Flaggers will be on site to facilitate truck entry and exit.
Planned construction (Folsom to Harrison):
- Monitor ground conditions and improve them as needed.
Traffic and pedestrian impacts (Folsom to Harrison):
- The parking lane and one lane of traffic on the eastern side of the street (in front of Whole Foods) will be closed
Stockton Street is now reopened to traffic and will remain open through New Year's Day. Union Square
Stockton Street from Market to Post
On Stockton Street between Geary and Ellis streets, work is currently paused. Central Subway Stations contractor Tutor Perini plans to begin station construction in January.
Ground improvement related to tunneling will be in progress on Ellis Street between Stockton and Powell streets.
Planned construction:
- No construction planned
- The work zone on Ellis Street will remain in place until after the second TBM passes through the area
Traffic, transit and pedestrian impacts (Stockton Street):
- Stockton Street will remain open at least until Jan. 2, 2014
- Ellis Street between Stockton and the Ellis-O'Farrell Garage (between Stockton and Powell) will remain closed to westbound traffic
More information about construction at this site is available in this construction notice and this press release. 
This small section of Washington Street, just west of Stockton Street, is now closed as we prepare to construct underground subway station walls beneath the street. Chinatown
Stockton Street from Sacramento to Broadway
To prepare to build the Chinatown Station, contractor Tutor Perini has demolished the existing building at 933-949 Stockton Street. Preparatory construction is now underway within the property lines and nearby on Washington Street and Stockton Street.
Planned construction:
- Build shallow underground walls (guide walls) in preparation for station wall construction
- Perform utility work on Washington Street within the construction zone
- Tentative: Install pedestrian ramp at northwest corner of Stockton and Washington
- Tentative: Perform underground borings on Clay and Jackson streets adjacent to Stockton Street. This work will take place at night.
Traffic, transit and pedestrian impacts:
- Washington Street between Stockton and Trenton will remain closed to vehicles and pedestrians
- Washington Street between Powell and the construction zone has been converted into a two-way street
- On Clay and Jackson, traffic will be routed around construction zones while construction is in progress
- To ensure safety, please obey all traffic and pedestrian signs in the area
Construction is currently paused on Columbus Avenue, with the roadway restored until construction resumes in January. North Beach
Powell Street from Union to Columbus
On private property at 1731-1741 Powell Street, the contractor is building a walled excavation known as a retrieval shaft at the site where tunneling will end. The two tunnel boring machines will be removed from the ground here. We plan to complete work at this location in 2014.
Near the intersection of Columbus Avenue and Union Street, construction is currently paused. The contractor will complete utility work next year. More information is available in this flier.
On private property at 1455 Stockton Street, the contractor is constructing an underground shaft to perform ground improvements when the TBMs pass below Columbus Avenue.
Planned construction (Pagoda):
- Install pipes underground for ground improvements
- Construct retrieval shaft (subsurface walls)
- Planned construction hours are Monday to Saturday, 6 a.m. to 11 p.m.
Traffic, transit and pedestrian impacts (Pagoda):
- Several parking spaces may be closed in front of the property.
- The sidewalk in front of the property may be closed. A temporary walkway will be in place around the construction zone when the sidewalk is closed.
Planned construction (Columbus and Union):
- No construction planned
Traffic, transit and pedestrian impacts (Columbus and Union):
- None
Planned construction (1455 Stockton):
- Install work platform and ground improvement components
- Planned work hours are Monday-Friday, 7 a.m. to 3:30 p.m.
- One morning next week, heavy equipment will be delivered to the site before regular working hours
Traffic, transit and pedestrian impacts (1455 Stockton):
- No impacts to traffic, transit or pedestrian walkways are anticipated
- The parking lot at 1455 Stockton will remain closed
Central Subway Construction Fast Facts
Project Alignment: 4th Street between Berry and Market streets; Stockton Street between Market Street and Columbus Avenue; Powell Street between Union Street and Columbus Avenue; Columbus Avenue between Powell and Filbert streets.
Transit Reroutes: The southbound 8X/8AX/8BX Bayshore Express, 30 Stockton, 45 Union/Stockton and 91 Owl Muni bus routes have been rerouted to accommodate construction in Union Square and SoMa. These reroutes will remain in effect throughout the duration of Central Subway construction. More information is available online here.
Contact Us: Should you have questions about construction or the Central Subway Project, don't hesitate to contact our team. You can reach us at central.subway@sfmta.com or by phone 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, Instagram or Flickr, and check out our blog.
Construction schedules are subject to change.