'Ton mile' definitions:

Definition of 'Ton mile'

From: GCIDE

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. [Webster 1913 Suppl.]