Cal. Veh. Code § 22452.5
The Department of Transportation and local authorities, with respect to highways under their respective jurisdictions, may place signs at railroad grade crossings permitting any vehicle described in subdivision (a) of Section 22452 to traverse such crossings without stopping. Such signs shall be placed in accordance with criteria adopted by the Public Utilities Commission. Prior to placing such signs, the Department of Transportation or local authority shall consult with the Department of the California Highway Patrol, railroad corporations involved, and the operators involved and shall secure the permission of the Public Utilities Commission if a railroad corporation under the jurisdiction of the Public Utilities Commission is affected. Prior to permitting the placement of such signs, the Public Utilities Commission shall seek the concurrence of the Department of the California Highway Patrol.
Ca. Veh. Code § 22452.5