Whenever the Council by motion or resolution designates any street or alley or part thereof as a one- way street or alley, the City Manager shall have placed and maintained signs giving notice thereof and no regulation shall be effective unless the 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.
(47 O.S. § 11-308(a)) (`90 Code, § 20-58)