California Code, Streets and Highways Code - SHC § 186.5

Whenever local entities are unable to agree upon the number and width of traffic lanes for a street or road proposed to be constructed by any such entity where such specifications will affect the uniform flow of traffic on a road or street from one such local entity to another, the matter may be submitted to the department. The department shall thereupon endeavor to establish such specifications for such street or road proposed to be constructed, and, if established, such specifications shall be binding upon the local entity constructing such road or street.