Source: Computed By NBER By Dividing Series (Total Net Ton-Miles, Excluding Free Hauled) By Series (Freight Train-Miles).
This NBER data series m03079 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03079
Release: NBER Macrohistory Database
National Bureau of Economic Research, Net Ton-Miles Per Freight Train-Mile for Great Britain [M03079GBM463NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M03079GBM463NNBR/, July 1, 2015.