Hawaii Revised Statutes Division 1. Government § 291C-222

(a) The director of transportation by rules adopted in accordance with chapter 91, and the counties by ordinance, may designate high occupancy vehicle lanes as to roadways under their respective jurisdictions.

(b) Signs and other official traffic-control devices that designate high occupancy vehicle lanes shall be placed and maintained to advise drivers of the high occupancy vehicle requirement and the hours of usage. When the high occupancy vehicle lane also serves as a contraflow lane, the hours of usage as a high occupancy vehicle lane shall be the time when the lane is coned for use as a high occupancy vehicle lane.

(c) No motor vehicle shall be operated upon these lanes except in conformance with the instructions on the signs and other official traffic-control devices.

(d) A motorcycle may use any high occupancy vehicle lane, regardless of the number of occupants.

(e) Any vehicle authorized by rules adopted in accordance with chapter 91 may use any high occupancy vehicle lane, regardless of the number of occupants, when the use is determined to enhance public safety and improves traffic conditions.