- Location: San Francisco, California
- Owner: San Francisco Municipal Transportation Agency
- Engineer(s): PB/Telamon JV
- Partner(s): Impregilo S.p.A., S.A. Healy Company
- Contract Type: Fixed Lump Sum (competitive bid)
- Status: Completed
At the Central Subway Tunnel Project in the heart of San Francisco, the San Francisco Municipal Transportation Agency (SFMTA) set out to improve transit options for a densely populated neighborhood known for high public transportation ridership while also furthering business development along the new 1.7-mile rail line. Building twin subway tunnels is never simple, in mission or in undertaking. Building these subway tunnels under a city that’s been well established since the “Gold Rush” of the 1800s has meant confronting plenty of structural and historical challenges underground in addition to the soft ground and hard rock soil conditions. The Central Subway Tunnel project broadens access to Chinatown from neighborhoods served by an earlier phase of SFMTA’s overall Light Rail Program while also supporting tourism and business development along the busy 3rd Street corridor via four new stations.
Barnard, as lead member of a joint venture with S.A. Healy and Impregilo S.p.A. and with key subcontractors, worked around the City’s downtown traffic and schedule by initially constructing a TBM launch box under an I-80 overpass, scheduling key aspects of the work at night while much of the city slept, and unraveling a complex web of utilities previously buried in our path through busy retail hubs like Union Square. The twin Robbins TBMs holed through into a retrieval shaft in the North Beach neighborhood in mid-June 2014. Work continued on conversion of the recently constructed launch box to a concrete portal structure along with construction of five cross passages connecting the two tunnels. Our Barnard families saw their work from a local perspective, living in the City and fully understanding the challenges of commuting to work or patronizing businesses on their time off.
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