|SFMTA home > About Us > Press Room > Construction to Prepare for Central Subway Tunnel Moves Forward, Advancing Vital Extension of Muni Metro T Third Line|
Release date: June 7, 2012
*** Press Release ***
The San Francisco Municipal Transportation Agency (SFMTA), which oversees transportation in the city, today announced that construction of the Central Subway is ramping up this month, with major work to prepare for tunneling, including excavation of almost an entire city block, commencing next week in SoMa. This new stage of construction will be the first to build permanent elements of the Central Subway, kicking off the next phase of progress on this critical transit project.
On June 12 tunneling contractor Barnard Impregilo Healy Joint Venture will begin excavating and constructing a launch box at the site where tunneling will begin. The launch box will be built on 4th Street between Bryant and Harrison streets, beneath the I-80 overpass. At nearly 500 feet long, 50 feet wide and up to 40 feet deep, this major excavation will take up most of the block. Next year a pair of tunnel boring machines (TBMs) will start digging the Central Subway tunnels from the launch box, traveling north under 4th Street and then Stockton Street.
This year tunnel preparatory work will also take place at several other locations along the project alignment. In addition to the launch box, the tunneling contractor will construct below-ground walls, called headwalls, at two subway station sites, relocate utilities and perform ground-stabilization work to prepare for construction of the Central Subway tunnel.
Work to prepare for headwall installation, including potholing and utility relocation, is planned to begin this week on 4th Street between Folsom and Howard streets, at the site of the future Yerba Buena/Moscone Station. Headwall installation, which involves major excavation work and will require the use of heavy machinery, will soon follow. The walls will be constructed across 4th Street and reach a depth of about 100 feet.
“Crews will soon be building the first permanent components of the vital Central Subway extension of the T Third Line. This $233 million contract will create jobs—both directly and indirectly—and contribute to the local economy,” said Edward D. Reiskin, Director of Transportation. “The launch box will become the portal where T Third Line trains will descend to the Central Subway tunnel, and the headwalls will be integrated into two new subway stations. This work kicks off an exciting new phase for this essential upgrade of San Francisco’s public transportation system.”
Construction will take place at multiple locations on a staggered schedule. Frequent construction updates, including information about traffic, Muni and pedestrian impacts, will be available online on the Central Subway blog (www.CentralSubwayBlog.com), on Twitter (@Central_Subway) and on Facebook (www.facebook.com/CentralSubway).
Central Subway Tunnel: Summary of Preparatory Work
Those traveling, working and living in areas impacted by Central Subway construction can expect to see large construction equipment as well as an increase in noise, dust and truck traffic while work is in progress. The Central Subway team will continue to work closely with communities, local businesses and organizations to inform them of construction impacts and to ensure appropriate mitigation measures are in place. As work commences at new locations along the alignment, additional information on local impacts will be made available online and in media alerts.
Access to local businesses, residences and driveways will be maintained.
The following tunnel-related work is planned to occur in the coming months:
Several Muni bus routes will be impacted by Central Subway construction. As construction begins at additional locations, additional Muni routes may be impacted.
Traffic Impacts and Suggested Detours
The following describes ongoing traffic impacts at the tunnel launch box site and around Union Square. As construction commences at new locations, additional traffic impact information will be provided.
Launch Box Construction (4th Street between Bryant and Harrison streets):
Yerba Buena/Moscone Station Headwall Installation (4th Street between Folsom and Howard streets):
Construction around Union Square (Stockton Street between Market and Post streets):
About the Central Subway Project
The Central Subway Project will extend the T Third Line from the 4th Street Caltrain Station to Chinatown, providing a direct, rapid transit link from the Bayshore and Mission Bay areas to SoMa and downtown. Four new stations will be built along the 1.7-mile Central Subway Project alignment – a street-level station at 4th and Brannan streets and three subway stations: Yerba Buena/Moscone Station, Union Square/Market Street Station and Chinatown Station.
Travel times through this busy corridor will be significantly reduced by the Central Subway. During peak hours, current travel between Stockton and Washington streets and 4th and King streets takes more than 20 minutes on Muni trolley coach routes. On the Central Subway, the same trip will take less than eight minutes.
The Central Subway Project is the second phase of the SFMTA’s Third Street Light Rail Transit Project. The first segment of the T Third Line opened in April 2007, restoring light rail service to a high transit-ridership area of San Francisco for the first time in 50 years.
The Central Subway is expected to open to the public in 2019.
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