Haw. Rev. Stat. § 291C-221
As used in this part unless the context otherwise requires:
"High occupancy vehicle" means a vehicle carrying at least the minimum number of persons designated by the director of transportation as indicated on official signs and other official traffic-control devices, and other vehicles as provided by rules adopted in accordance with chapter 91 or by county ordinance.
"High occupancy vehicle lane" means a designated lane of a laned roadway where the use of the designated lane is restricted to school buses, vehicles carrying at least the minimum number of persons designated by the director of transportation on official signs and other official traffic-control devices, and to other vehicles as provided by rules adopted in accordance with chapter 91, or by county ordinance.
HRS § 291C-221