No person shall without lawful authority attempt to or in fact alter, deface, injure, knock down, or remove any official traffic control signal, traffic device or railroad sign or signal, or any inscription, shield, or insignia thereon, or any other part thereof.

Defacing, injuring, or destroying signs: RCW 46.61.080.

Imitation of signs: RCW 46.61.075.

Structures concealing signs prohibited: RCW 46.61.075.

Unlawful erection of traffic devices: RCW 46.61.075.