Ben Hammersley posts a parable about design specifications, showing the link between Roman Chariots and the Space Shuttle. It has the ring of something apocraphyl to me, but it's a good read, nevertheless.
The U.S. standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That is an exceedingly odd number. Why was that gauge used? Because that's the way they built them in England, and the U.S. railroads were built by English expatriates.
Why did the English build them that way? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that's the gauge they used.
Why did "they" use that gauge? Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing.
So why did the wagons have that particular odd spacing? Well, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance roads in England, because that was the spacing of the wheel ruts…
Snopes says it's false, but from their notes, it appears that it's actually largely true, albeit subject to interpretation.
