California Code, Streets and Highways Code - SHC § 30771

(a) “District” means the San Francisco Bay Area Rapid Transit District.

(b) “Rapid transit tube” means a subaqueous tube across San Francisco Bay between the City and County of San Francisco and the County of Alameda, its approaches and fixed transit facilities, including, but not limited to, ventilation towers and equipment, tracks, and electrical distribution, control, lighting, and communication systems for the accommodation of rail rapid transit.  The San Francisco terminus of the underwater portion of the rapid transit tube shall be located westward of the shoreline of San Francisco Bay as close thereto as may be reasonably practicable between Howard and Jackson Streets in the City and County of San Francisco.  The Alameda County terminus shall be the Southern Pacific mole or as close thereto as may be reasonably practicable.

(c) “Approaches” means all facilities between the terminus in Alameda County and the first station thereafter in the county for the discharge of passengers, and all facilities between the terminus in the City and County of San Francisco and the easterly end of the passenger platform of the Montgomery Street Station defined as “approaches” in the agreement between the department and the district, dated March 3, 1966.