Pursuant to RCW 46.61.570, the city council may by ordinance designate certain special parking zones for motor buses, taxicabs, police cars, fire department vehicles and automobiles, and other vehicles of a public or emergency nature. Authorized vehicles parked therein shall not be subject to provisions of any other general ordinance of the city prohibiting parking in the designated zones or areas, but the persons in charge of such authorized vehicles must be available nearby and must remove them promptly at the request of any city official or employee and for such time as public need or business shall require. Such special parking zones shall be clearly marked by appropriate signs and curb painting, and it is unlawful for anyone to park unauthorized vehicles therein.