Cal. Pub. Util. Code § 25801

A district may acquire, construct, own, operate, control or use rights of way, rail lines, bus lines, stations, platforms, switches, yards, terminals, and any and all other facilities necessary or convenient for transit service within or partly without the district, underground, upon, or above the ground and under, upon, or over public streets or other public ways or waterways, together with all physical structures necessary or convenient for the access of persons and vehicles thereto, and may acquire any interest in or rights to the joint use of any or all of the foregoing; provided, that installations in state freeways shall be subject to the approval of the State Department of Public Works and installations in other state highways shall be subject to Article 2, Chapter 3, Division 1 of the Streets and Highways Code.