(1) Every authorized emergency vehicle and organ transport vehicle shall, in addition to any other equipment and distinctive marking required by this chapter, be equipped with at least one lamp capable of displaying a red light visible from at least 500 feet in normal sunlight and a siren capable of giving an audible signal.
(2) Every school bus and private carrier bus shall, in addition to any other equipment and distinctive markings required by this chapter, be equipped with a "stop" signal upon a background not less than 14 by 18 inches displaying the word "stop" in letters of distinctly contrasting colors not less than five and nine-tenths inches high, and shall further be equipped with signal lamps mounted as high and as widely spaced laterally as practicable, which shall be capable of displaying to the front two alternately flashing red lights located at the same level and to the rear two alternately flashing red lights located at the same level and these lights shall have sufficient intensity to be visible at 500 feet in normal sunlight.
(3) Vehicles operated by public agencies whose law enforcement duties include the authority to stop and detain motor vehicles on the public highways of the state may be equipped with a siren and lights of a color and type designated by the state patrol for that purpose. The state patrol may prohibit the use of these sirens and lights on vehicles other than the vehicles described in this subsection.
(4) The lights described in this section shall not be mounted nor used on any vehicle other than a school bus, a private carrier bus, an authorized emergency or law enforcement vehicle, or an organ transport vehicle.
(5) The use of the signal equipment described in this section and RCW 46.37.670
, except the signal preemption devices used by public transit vehicles and department of transportation, city, or county maintenance vehicles that are not used in conjunction with emergency equipment, shall impose upon drivers of other vehicles the obligation to yield right-of-way and stop as prescribed in RCW 46.61.210
, and 46.61.350