34 Pa. Code § 31.11
The following words and terms, when used in this subchapter, have the following meanings, unless the context clearly indicates otherwise:
Bus-Any motor vehicle designed, constructed and used for the transportation of passengers, with the exception of passenger automobiles or station wagons other than taxicabs.
Carrier of migrant worker by motor vehicle-Any person or any contract carrier by motor vehicle, not including common carriers, by motor vehicle, who or which transports in interstate, intrastate or foreign commerce at any one time three or more migrant workers to or from their employment by any motor vehicle other than a passenger automobile or station wagon, except a migrant worker transporting himself or his immediate family.
Driver or operator-Any person who drives any motor vehicle.
Highway-The entire width between the boundary lines of every way publicly maintained when any part of it is open to the use of the public for vehicular traffic.
Migrant worker-Any interstate or intrastate individual whose primary employment is in agriculture, on a seasonal or other temporary basis, or any individual irrespective of his primary employment, if he performs agricultural labor on a seasonal or other temporary basis. This term includes all seasonal workers, migrant workers or farm labor who are not year round employes and who occupy living quarters other than their permanent home during the period of such work on a farm.
Motor carrier-Any carrier of migrant workers by motor vehicle.
Motor vehicle-Any vehicle, machine, tractor trailer or semitrailer, or any combination of any of these as determined by the commission, propelled or drawn by mechanical power and used upon the highways in the transportation of passengers or property. This term does not include a vehicle, locomotive or car operated exclusively on a rail or rails, or a trolley bus operated by electric power derived from a fixed overhead wire, furnishing local passenger transportation in street-railway service.
Semitrailer-Any motor vehicle other than a pole trailer with or without motive power, designed to be drawn by another motor vehicle and so constructed that some part of its weight rests upon the towing vehicle.
Truck-Any self-propelled motor vehicle except a truck tractor, designed and constructed primarily for the transportation of property.
Truck tractor-A self-propelled 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 weight of the vehicle and load so drawn.
34 Pa. Code § 31.11