(a) The Director of Public Works is authorized and directed to adopt signs, signals, devices, and markings to regulate, warn, and guide traffic.
(b) The Director of Public Works is authorized to place and maintain, or cause to be placed and maintained, any traffic control devices, signals, signs, and markings as he may deem necessary to continue and carry out the provisions of this chapter, subject to the approval of the City Council.
(c) The existence of a traffic control device signal or sign shall constitute prima facie evidence that such is an official traffic control device, signal, or sign lawfully erected and placed.