(1) It is unlawful for any person to operate upon the public highways of this state any vehicle having an overall length, with or without load, in excess of forty feet. This restriction does not apply to (a) a municipal transit vehicle, (b) auto stage, private carrier bus, school bus, or motor home with an overall length not to exceed forty-six feet, (c) an articulated auto stage with an overall length not to exceed sixty-one feet, excluding a bike rack up to four feet in length, or (d) an auto recycling carrier up to forty-two feet in length manufactured prior to 2005.

(2)(a) It is unlawful for any person to operate upon the public highways of this state any combination consisting of a tractor and semitrailer that has a semitrailer length in excess of fifty-three feet or a combination consisting of a tractor and two trailers in which the combined length of the trailers exceeds sixty-one feet, with or without load.

(b) The restriction under this subsection (2) does not apply to combinations of vehicles operating on highways designated by the department of transportation as part of a pilot project authorized by RCW 46.44.036(2). The total combination of vehicles under this subsection (2)(b) may not exceed one hundred five feet of overall length.

(c) The restriction under this subsection (2) does not apply to two trailers or semitrailers with a total weight that does not exceed twenty-six thousand pounds and when the two trailers or semitrailers do not carry property but constitute inventory property of a manufacturer, distributor, or dealer of such trailers. The total combination under this subsection (2)(((b)))(c) may not exceed eighty-two feet of overall length.

(3) It is unlawful for any person to operate on the highways of this state any combination consisting of a truck and trailer, or log truck and stinger-steered pole trailer, with an overall length, with or without load, in excess of seventy-five feet. "Stinger-steered," as used in this section, means the coupling device is located behind the tread of the tires of the last axle of the towing vehicle.

(4)(a) The length limitations under this section do not apply to vehicles transporting poles, pipe, machinery, or other objects of a structural nature that cannot be dismembered and operated by a public utility when required for emergency repair of public service facilities or properties, but in respect to night transportation every such vehicle and load thereon shall be equipped with a sufficient number of clearance lamps on both sides and marker lamps upon the extreme ends of any projecting load to clearly mark the dimensions of the load.

(b) Excluded from the calculation of length under this section are certain devices that provide added safety, energy conservation, or are otherwise necessary, and are not designed or used to carry cargo. The length-exclusive devices must be identified in rules adopted by the department of transportation under RCW 46.44.101.

(1) Except as provided in RCW 46.44.037 and subsection (2) of this section, it is unlawful for any person to operate upon the public highways of this state any combination of vehicles consisting of more than two vehicles. For the purposes of this section, a truck tractor-semitrailer or pole trailer combination will be considered as two vehicles but the addition of another axle to the tractor of a truck tractor-semitrailer or pole trailer combination in such a way that it supports a proportional share of the load of the semitrailer or pole trailer shall not be deemed a separate vehicle but shall be considered a part of the truck tractor. For the purposes of this section, a converter gear used in converting a semitrailer to a full trailer shall not be deemed a separate vehicle but shall be considered a part of the trailer.

(2) Until June 30, 2024, the state department of transportation must implement a pilot project to allow combinations of vehicles consisting of no more than three vehicles to operate on designated public highways of the state. The department of transportation may also specify other operating conditions to ensure a safe and efficient highway system.

(b) By January 1st of each year through 2024, the department of transportation must submit a status and performance report on the implementation of the pilot project.