Définition
A tonne-kilometre is a measurement unit corresponding to the transport of one ton over a distance of one kilometre.
Remarque
This term is defined by analogy with the notion of "effort" in physics. As compared to tons, ton-miles have the advantage that they can be added together: transport of 10 tons over 100 miles followed by the transport of 10 tons over 50 miles comes to a total of 1,500 ton-miles, whereas the addition of the weights transported is meaningless.