The Collaborative International Dictionary
Ton mile
Ton mile \Ton mile\ (Railroads) A unit of measurement of the freight transportation performed by a railroad during a given period, usually a year, the total of which consists of the sum of the products obtained by multiplying the aggregate weight of each shipment in tons during the given period by the number of miles for which it is carried.
Wiktionary
ton mile
n. A unit of measure expressed in number of short tons moved over a specific distance in miles'''US FM 55-15 '' TRANSPORTATION REFERENCE DATA; 9 June 1886'''''.
Usage examples of "ton mile".
After that, transport costs by riverboat weren't nearly so bad, about one-twelfth the cost per ton mile.