Subject to additional definitions contained in subsequent provisions of this title which are applicable to specific provisions of this title, the following words and phrases when used in this title shall have, unless the context clearly indicates otherwise, the meanings given to them in this section:
"Official traffic-control devices." Signs, signals, markings and devices not inconsistent with this title placed or erected by authority of a public body or official having jurisdiction, for the purpose of regulating, warning or guiding traffic.