The safety-service director is authorized and required to ascertain upon what highways and parts of highways and all other municipal property the accommodation of traffic or the safety of the public require the restriction as to time, or the prohibition of the parking or stopping of vehicles. He shall erect and maintain appropriate traffic signs plainly indicating the purpose of the restrictions. It shall be unlawful to park or stop a vehicle in violation of a traffic sign so erected.
('73 Code, § 73.01)