“Official traffic-control devices” means all signs, signals, markings, and devices not inconsistent with this chapter placed or erected by authority of a public body or official having jurisdiction, for the purpose of regulating, warning, or guiding traffic.
“Official traffic-control signal” means any device, whether manually, electrically or mechanically operated, by which traffic is alternately directed to stop and to proceed.
“Railroad sign or signal” means any sign, signal, or device erected by authority of a public body or official or by a railroad and intended to give notice of the presence of railroad tracks or the approach of a railroad train.