Streets and Highways Code § 941.2
CHAPTER 2. Powers and Duties of Boards of Supervisors
Boards of supervisors may close any street or highway within their jurisdiction at or near the point of its intersection with any freeway, or may make provision for carrying such street or highway over, under, or to a connection with the freeway, and may do any and all work on such street or highway as is necessary therefor.
No public highway shall be converted into a freeway except with the consent of the owners of abutting lands or the purchase or condemnation of their right of access thereto.