Drivers subject to the HOS include any driver of a vehicle which has a gross vehicle weight of 10001 pounds or more; which is designed or used to transport more than 8 passengers (including the driver) for compensation; which is designed or used to transport more than 15 passengers (including the driver) and is not used to transport passengers for compensation; or which is used to transport hazardous materials in quantities requiring the vehicle to be marked or placarded under the hazardous materials regulations.