Whenever any ordinance of the City designates any one-way street
or alley, the City 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.