Whenever any ordinance of the city designates any one-way street or alley, the mayor or any person designated by him shall place and maintain signs giving notice thereof, and no ordinance establishing one-way streets shall be effective unless signs required by this section are in place. Signs indicating the direction of lawful traffic movement shall be placed at every intersection where movement of traffic in the opposite direction is prohibited. (Ord. 77, 9-4-1973)