From the junction of United States highway 81 and K-18 highway then west on K-18 highway to the western boundary of Lincoln county is hereby designated as the Medal of Honor recipient Donald K. Ross memorial highway. The secretary of transportation shall place signs along the highway right-of-way at proper intervals to indicate that the highway is the Medal of Honor recipient Donald K. Ross memorial highway, except that such signs shall not be placed until the secretary has received sufficient moneys from gifts and donations to reimburse the secretary for the cost of placing such signs and an additional 50% of the initial cost to defray future maintenance or replacement costs of such signs. The secretary of transportation may accept and administer gifts and donations to aid in obtaining and installing suitable signs.