RCW 46.61.165
High occupancy vehicle lanes — Definition.
(1) The state department of transportation and the local authorities are authorized to reserve all or any portion of any highway under their respective jurisdictions, including any designated lane or ramp, for the exclusive or preferential use of one or more of the following: (a) Public transportation vehicles; (
motorcycles; © private motor vehicles carrying no fewer than a specified number of passengers; or (d) the following private transportation provider vehicles if the vehicle has the capacity to carry eight or more passengers, regardless of the number of passengers in the vehicle, and if such use does not interfere with the efficiency, reliability, and safety of public transportation operations: (i) Auto transportation company vehicles regulated under chapter
81.68 RCW; (ii) passenger charter carrier vehicles regulated under chapter
81.70 RCW, except marked or unmarked stretch limousines and stretch sport utility vehicles as defined under department of licensing rules; (iii) private nonprofit transportation provider vehicles regulated under chapter
81.66 RCW; and (iv) private employer transportation service vehicles, when such limitation will increase the efficient utilization of the highway or will aid in the conservation of energy resources.
468-510-010
High occupancy vehicles (HOVs).Pursuant to RCW
46.61.165 and 47.52.025, the department has reserved portions of interstate highways, state highways, and ramps, as HOV lanes for the exclusive use of public transportation vehicles or private motor vehicles with the number of occupants specified on signs. Motor vehicles authorized to use HOV lanes are:
(1) Rubber tired municipal transit vehicles conforming to RCW
46.04.355.
(2) Buses with a carrying capacity of sixteen or more persons, including the operator.
(3) Motorcycles conforming to RCW
46.04.330.
(4) Recreational vehicles with the number of occupants specified on signs.
(5) Official marked law enforcement and fire department vehicles equipped with emergency lights and siren, operated by an on-duty state patrol, local, or county law enforcement personnel, or on-duty local, county, or special district fire department personnel.
(6) All other vehicles with the number of occupants specified on signs, except that trucks in excess of 10,000 lb. G.V.W. are prohibited from the use of HOV lanes regardless of the number of occupants. Tow trucks that would be otherwise prohibited because of weight or number of occupants may use HOV lanes when en route to an emergency on a specific roadway or roadside.
I wonder why a bike needs a transponder for the HOV lanes anywhere in this state. I got mine since my work pays for it.