(a)Any highway routing designation established, maintained, or enforced by a State, political subdivision thereof, or Indian tribe is preempted if—
(1)Compliance with both the highway routing designation and any requirement under the Act or of a regulation issued under the Act is not possible;
(2)The highway routing designation as applied or enforced creates an obstacle to the accomplishment and execution of the Act or the regulations issued under the Act; or
(3)The highway routing designation is preempted pursuant to § 397.69(b) of this part.