The traffic control and regulation of all public streets shall be as posted, regulated or controlled by appropriate traffic control devices, signs or other regulatory devices or controls. The city engineer shall place and maintain all traffic control devices when and as required under the ordinances of this city to make effective the provisions of said ordinances, and may place and maintain such additional traffic control devices as he may deem necessary to regulate, guide or warn traffic under the traffic ordinances of this city. [Code 2000 § 6-2-4].