All traffic control devices including signs, signals, and markings (pavement and/or curb) installed or used for the purpose of directing and controlling traffic within the city shall conform with the Texas Manual on Uniform Traffic Control Devices for Streets and Highways, Volumes I and II (hereafter called the manual). All signs, signals, and markings erected or used by the city shall be uniform and located so far as practicable according to the directions shown in the manual. All existing traffic control devices and those erected in the future by the city being consistent with the manual, state law, and this chapter shall be official traffic control devices.