nd Lieutenant Justin L Sisson memorial highway. That portion of United States highway 69 from the junction of United States highway 69 and 135th street in Johnson county, then south on United States highway 69 to the junction of United States highway 69 and 167th street is hereby designated as the 2nd Lieutenant Justin L Sisson memorial highway. The secretary of transportation shall place highway signs along the highway right-of-way at proper intervals to indicate that the highway is the 2nd Lieutenant Justin L Sisson 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.