Word Study
traffic mile
CIDE DICTIONARY
traffic mile,
Any unit of the total obtained by adding the passenger miles and ton miles in a railroad's transportation for a given period; -- a term and practice of restricted or erroneous usage.
"Traffic mile is a term designed to furnish an excuse for the erroneous practice of adding together two things (ton miles and passenger miles) which, being of different kinds, cannot properly be added." [Webster 1913 Suppl.]
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