Any junkyard lawfully in existence on May 6, 1966, or which is or may be lawfully established along any highway which is hereafter made a part of the interstate or primary systems and which has been so established before the inclusion of the highway within the interstate or primary systems and which is within one thousand feet (1000?) of the nearest edge of the right-of-way and visible from the main traveled way of any highway on the interstate or primary system, shall be screened, if feasible, by the director of transportation at locations on the highway right-of-way or in areas acquired for such purposes outside the right-of-way so as not to be visible from the main traveled way of the highways; provided, however, that nothing contained herein shall be construed to relieve the owners or operators of automobile junkyards from the provisions of chapter 21 of Title 5 relating to the screening thereof.