Cal. PUC § 1202.3

Notwithstanding any other provision of this chapter, in any proceeding under Section 1202, in the case of a crossing involving a publicly used road or highway not on a publicly maintained road system, the commission may apportion expense for improvements to the county in the case of unincorporated territory, city or other political subdivision if the commission finds (a) that the owner or owners of private property served by such publicly used crossing agree to expressly dedicate and improve, and the affected public agency agrees to accept, a right-of-way or roadway over such property for a reasonable distance from such crossing as determined by the commission, or (b) that a judicial determination of implied dedication of such road or highway over the railroad right-of-way to public use, based on public user in the manner and for the time required by law, has taken place.

If neither of these conditions is found to exist, the commission shall order the crossing abolished by physical closing.

In no event shall a railroad be required to bear costs for the improvement of a publicly used crossing in excess of what it would be required to bear in connection with the improvement of a public street or highway crossing.