Veh. Code, § 38026

(a) In addition to Section 38025 and after complying with subdivision (c) of this section, if a local authority, an agency of the federal government, or the Director of Parks and Recreation finds that a highway, or a portion of a highway, under the jurisdiction of the authority, agency, or the director, as the case may be, is located in a manner that provides a connecting link between off-highway motor vehicle trail segments, between an off-highway motor vehicle recreational use area and necessary service facilities, or between lodging facilities and an off-highway motor vehicle recreational facility and if it is found that the highway is designed and constructed so as to safely permit the use of regular vehicular traffic and also the driving of off-highway motor vehicles on that highway, the local authority, by resolution or ordinance, agency of the federal government, or the Director of Parks and Recreation, as the case may be, may designate that highway, or a portion of a highway, for combined use and shall prescribe rules and regulations therefor. A highway, or portion of a highway, shall not be so designated for a distance of more than three miles, except as provided in Sections 38026.1, 38026.2, and 38026.3. A freeway shall not be designated under this section.

(b) The Off-Highway Motor Vehicle Recreation Commission may propose highway segments for consideration by local authorities, an agency of the federal government, or the Director of Parks and Recreation for combined use.

(c) Prior to designating a highway or portion of a highway on the motion of the local authority, an agency of the federal government, or the Director of Parks and Recreation, or as a recommendation of the Off-Highway Motor Vehicle Recreation Commission, a local authority, an agency of the federal government, or the Director of Parks and Recreation shall notify the Commissioner of the California Highway Patrol, and shall not designate any segment pursuant to subdivision (a) which, in the opinion of the commissioner, would create a potential traffic safety hazard.

(d) (1) A designation of a highway, or a portion of a highway, under subdivision (a) shall become effective upon the erection of appropriate signs of a type approved by the Department of Transportation on and along the highway, or portion of the highway.

(2) The cost of the signs shall be reimbursed from the Off-Highway Vehicle Trust Fund, when appropriated by the Legislature, or by expenditure of funds from a grant or cooperative agreement made pursuant to Section 5090.50 of the Public Resources Code.