All traffic control signs, signals and devices shall so far as practicable conform to the most recent version of the “Manual of Uniform Traffic Control Devices” published by the Federal Highway Administration, U.S. Department of Transportation. All signs and signals required hereunder for a particular purpose shall so far as practicable be uniform as to type and location throughout the townsite service area. All traffic control devices so erected and not inconsistent with the provisions of state law or this chapter shall be official traffic control devices.