Cal. Sts. & High. Code § 2180

When considering the feasibility of rail access from the San Francisco Bay area to Sacramento and Stockton, the department shall explore, for future development, the feasibility of providing such access through connection to the San Francisco Bay Area Rapid Transit District transit system in the vicinity of corridors formed by State Highway Routes 4, 24, and 680. The department, in consultation with the district, shall also explore the feasibility of limited extension of the district’s rail system to the vicinity of Concord along the Sacramento Northern rights-of-way.