The department shall replace or cause to be replaced any city limit road sign if all the following conditions exist:
(a) If the legislative body of a city requests the replacement.
(b) If the request is based upon a substantial change of population evidenced by a special or general federal census.
(c) If no previous request has been made by the city within a period of five years.
(Added by renumbering Section 101.3 by Stats. 1961, Ch. 57.)