Truck Tractors and Semi-trailers:
A Truck Tractor is a vehicle configuration consisting of a power-unit designed to draw/pull a semi-trailer. Thus, the truck tractor itself has no cargo carrying capability without an attached semi-trailer. A semi-trailer is constructed so that some part of the weight rests upon the power unit. A truck tractor towing another motor vehicle is considered a "truck tractor" vehicle configuration. These vehicle configurations are recorded in SAFETYNET based upon the presence and number of attached semi-trailers as follows.
- Truck Tractor (Bobtail)
- Tractor Semi-trailer (1 trailer)
- Tractor/Doubles (2 trailers)
- Tractor/Triples (3 trailers)