4 ms·

Related: Why the space shuttle size is related to a horse's back end :) http://www.astrodigital.org/space/stshorse.html http://www.astrodigital.org/space/stsho

• jcranmer 10y ago
  That is more fiction than fact. The first railroads in the US and UK standardized fairly quickly on 4'8½", but that's not the only size (even today!). The Great Western Railway, for example, was infamously at a 7' gauge. Even in the US, most railroads in the south converged on a 5' gauge until they shifted to 4'9" (not 4'8½"!) on May 31, 1886. The gauge differences in very early (1820s and 1830s) railways were just as diverse as the coal tramways that proceeded them--which means you basically have every value between 4'6" and 5' as the actual track gauge. Of course, that belies the fact that your track gauge does not determine what you can stick on a train. That's the loading gauge, and these are nowhere near as consistent. The UIC standard loading gauge in Europe is 3.15 m wide, while the standard US loading gauge is 3.25 wide--and they both share the 4'8½" track gauge. (Note: the actual adherence to these standards, particularly in 100+ year-old railways, is a different matter.)