(1) Except as permitted by the act and these regulations, no person shall erect or maintain a sign which is visible from the main-traveled way of the interstate system, the primary system, or the scenic system. Signs visible to other types of state highways are not restricted by the Scenic Vistas Act or these regulations, but are subject to local ordinances.

(2) In case a highway or a section of highway is a part of both the primary system and the scenic system, only those signs permitted along the scenic system may be erected or maintained.