SFMTA Union Square Market Street Station

New underground light rail station completed in 2023

The Central Subway is a 1.7-mile extension of Muni Metro’s T-Third Street line with three new underground stations, including Union Square/Market Street Station. The station entrance occupies one corner of Union Square. At the south end, the station connects to other Muni lines and BART at the existing Powell Street Station. The 210-foot-long station platform level is located more than 70 feet below ground.

SFMTA Union Square Central Subway UMS section

The width of the right-of-way at street level was narrower than the station’s required operating width at platform level below. As a result, the excavation had to be wider at the bottom than the top. The engineers proposed the unusual solution of driving deep foundations at an angle from the vertical. The architects celebrated the achievement by leaving the cementitious pile walls exposed, with a smoother, finer grain at the concourse level and a rougher, coarser grain down at platform level. Sleek, modular panels display transit information, area information, advertisements, and wayfinding directions.

Central Subway entrance view

Related underground transit projects:  Caltrain 4th & Townsend Station, 28th Ave Little Portugal Station, Civic Center Station Modernization, Powell Staton Modernization, Montgomery Station Modernization, Embarcadero Station Modernization, BART Transbay Tube Enhancements


San Francisco, CA

Construction Cost

$200 million+


San Francisco Municipal Transportation Agency (SFMTA)

Prime Consultant

Central Subway Design Group


Robin Chiang & Company