Just compensation shall be paid upon the removal of any advertising sign, display, or device lawfully erected or in existence prior to May 27, 1975, and not conforming to the provisions of sections 39-202 to 39-205, 39-215, 39-216, and 39-220 except as otherwise authorized by such sections. The Department of Transportation shall not be required to expend any funds under the provisions of such sections unless and until federal-aid matching funds are made available for this purpose.