"Traffic" means pedestrians, ridden or herded animals, vehicles and other devices, either singly or together, while using for purposes of travel any street or highway or private road open to public travel. (ORC 4511.01(TT))
“Traffic control device” means a flagger, sign, signal, marking, or other device used to regulate, warn or guide traffic, placed on, over, or adjacent to a street, highway, private road open to public travel, pedestrian facility, or shared-use path by authority of a public agency or official having jurisdiction, or, in the case of a private road open to public travel, by authority of the private owner or private official having jurisdiction.
(ORC 4511.01(QQ))