Prohibits the following vehicles from being restricted from a highway in the state designated as a high occupancy vehicle lane: (1) An officially marked law enforcement or fire department vehicle equipped with emergency lights and siren operated by on-duty state patrol or local law enforcement personnel or on-duty local or special district fire department personnel; and

(2) An unmarked law enforcement vehicle operated by on-duty state patrol or local law enforcement personnel in the process of being used to conduct an active investigation.