Whenever used in this chapter, the term: “Carrier” means a person who operates or causes to be operated a commercial highway vehicle on any highway in the Commonwealth. “Department” means the Department of Motor Vehicles, acting through its officers and agents. “Identification marker” means a decal issued by the Department to show that a vehicle operated by a carrier is properly registered with the Department for the payment of the road tax. “IFTA” means the International Fuel Tax Agreement, as entered into by the Department, and as amended by the International Fuel Tax Association, Inc. “Licensee” means a carrier who holds an uncancelled IFTA license issued by the Commonwealth. “Motor carrier” means every person, firm or corporation who owns or operates or causes to be operated on any highway in this Commonwealth any qualified highway vehicle. “Operations” means the physical activities of all such vehicles, whether loaded or empty, whether for compensation or not for compensation, and whether owned by or leased to the motor carrier who operates them or causes them to be operated. “Qualified highway vehicle” means a highway vehicle used, designed, or maintained for transportation of persons or property that (i) has two axles and a gross vehicle weight or registered gross vehicle weight exceeding 26,000 pounds or 11,797 kilograms, (ii) has three or more axles regardless of weight, or (iii) is used in combination, when the weight of such combination exceeds 26,000 pounds or 11,797 kilograms gross vehicle or registered gross vehicle weight. “Qualified highway vehicle” does not include recreational vehicles. “Tractor truck” means every motor vehicle designed and used primarily for drawing other vehicles and not so constructed as to carry a load other than a part of the load and weight of the vehicle attached thereto. “Truck” means every motor vehicle designed to transport property on its own structure independent of any other vehicle and having a registered gross weight in excess of 7,500 pounds.