WAC 204-21-170

(1) Additional headlamps may be positioned sufficiently high enough to clear operating equipment provided they are aimed at an angle to avoid blinding oncoming traffic while on their routes, involved in construction, maintenance, and/or operations. Except, refuse haulers must:

(a) Use regular mounted headlamps when transporting refuse to the dump site. Auxiliary headlamps may be used if necessary.

(b) Use the alternate lights when the refuse haulers' collections container is in a position to obscure the headlamps, and will not exceed 20 miles per hour.

(2) Additional operating lamps may be located on the top of the cab or at other locations to illuminate plowing, abrasive spreading or other equipment.

(3) No flashing red warning signal except those required by RCW 46.37.150 will be displayed or used on any highway equipment.

(4) Snow removal vehicles owned or operated by state, county, or municipal agencies and highway maintenance vehicles may be equipped with flashing green and white lamps, in addition to amber lamps.

(a) The green and white lamps must be:

(i) Of sufficient intensity to be clearly visible to approaching traffic from a distance of at least 500 feet in normal sunlight; and

(ii) Must be mounted in accordance with WAC 204-21-020 and must be positioned so that the entire projected area of the lens is visible to drivers of other vehicles at all eye heights within an angle of 45 degrees to the left and 45 degrees to the right of the front of the vehicle. If the lamp is obstructed within these angles by the vehicle or any substantial component on it, an additional amber lamp must be displayed within the obstructed angle.

(b) The green and white lamps may only be illuminated while the vehicle is actively engaged in snow and ice removal or highway maintenance operations and must not be illuminated while the vehicle is traveling to or from the site of operations.

(c) The use of green and white lamps does not confer any privileges granted to authorized emergency vehicles as defined in RCW 46.61.035.

(5) Amber colored lamps must:

(a) Be mounted on the cab or other high point of the equipment so as to be visible at all times, at least from the front and rear of the vehicle, from a distance of 500 feet in normal sunlight, unless otherwise prescribed below.

(b) Have a minimum light intensity of the lamp filament not be less than 21 candle power.

(c) Be used on the following vehicles:

(i) Power shovels or other similar highway maintenance equipment. The amber lamp and a red flag are to indicate an extension which designates the maximum danger limit created by the swing of the cab while operating along the traffic lane.

(ii) Other highway equipment which creates a potential hazard to traffic including those vehicles and trailers for construction, maintenance, and operations.

(iii) Knuckle of all man lift-type platform trucks with articulating boom, where the knuckle is capable of being rotated beyond the side of the truck.

(d) Only be illuminated:

(i) When the equipment is actually involved in construction, maintenance, collecting refuse, and/or operations.

(ii) When the equipment is traveling to or from the job site and is unable to maintain, either because of equipment limitations, or other reasons, at least one-half posted or prevailing speed.