As used in this article, the term "traffic sign" shall mean any traffic sign, traffic signal, warning sign, guideboard, milepost, road marker, emergency telephone sign, or any similar sign, signal, or device used by the state or any political subdivision of the state on the highways, roads, bridges, or streets of this state for the warning, instruction, or information of the public.
Ala. Code § 13A-8-70 (1975)