• The Chinatown station, a subway station with an entrance at Stockton and Washington streets;
• The Union Square/Market Street station, a subway station with entrances at Stockton and Geary streets and Stockton and Ellis streets;
• The Yerba Buena/Moscone station, a subway station with an entrance at 4th and Clementina streets.
In addition, the project includes a surface-level station at 4th and Brannan streets.
Each TBM consists of a rotating cutter wheel (the cutter head), a cylindrical steel shell (the shield) and a 300-foot train of tunnel-building mechanisms (the trailing gear). The TBMs arrive in several parts and are assembled in about six weeks underneath 4th Street between Harrison and Bryant streets, the site where tunneling will begin. The tunnels will end in North Beach, at the site of the former Pagoda Palace Theatre on Powell Street.
The central subway is expected to open to the public in 2019.