California Code, Vehicle Code - VEH § 21107.5

(a) Any city or county may, by ordinance or resolution, find and declare that there are privately owned and maintained roads as described in the ordinance or resolution within the city or county that are generally held open for use by the public for vehicular travel and which so connect with highways that the public cannot determine that the roads are not highways. Upon enactment by a city or county of the ordinance or resolution, this code shall apply to the privately owned and maintained road, except as provided in subdivision (b).

(b) No ordinance or resolution enacted under subdivision (a) shall apply to any road on which the owner has erected a notice of a size, shape, and color as to be readily legible during daylight hours from a distance of 100 feet to the effect that the road is privately owned and maintained and that it is not subject to public traffic regulations or control.

(c) No ordinance or resolution shall be enacted under subdivision (a) without a public hearing after 10 days' written notice to the owner of the privately owned and maintained road involved.

(d) The department is not required to provide patrol or enforce any provision of this code on any privately owned and maintained road, except those provisions applicable to private property, other than pursuant to this section.