All traffic-control signs, signals, and devices shall conform to the manual and specifications approved by the State Department of Highways, as referred to in IC 9-21-4-1 et seq. All signs and signals required hereunder for a particular purpose shall so far as practicable be uniform as to type and location throughout the city. All traffic- control devices so erected and not inconsistent with the provisions of state law or of this code shall be official traffic-control devices.
('75 Code, § 41.11)