Whenever any ordinance of the City designates any one-way street
or alley, the City Traffic Engineer shall place and maintain signs
giving notice thereof, and no such regulation shall be effective unless
such signs 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.
Upon those streets and parts of streets and in those alleys
described and designated by ordinance, vehicular traffic shall move
only in the indicated direction when signs indicating the direction
of traffic are erected and maintained at every intersection where
movement in the opposite direction is prohibited.