The Board may transfer such highways, bridges, and streets as it deems proper from the primary or secondary state highway system to the Interstate System. Upon such transfer, the highways, bridges, and streets so transferred shall become for all purposes parts of the Interstate System and thereafter cease being parts of the primary or secondary state highway system. The Board may add such highways, bridges, and streets as it deems proper to the Interstate System without limitations as to mileage.
Va. Code § 33.2-304