Why Train Tracks Are This Exact Strange Width

Stop at any level crossing and there's a strangely exact number hiding between the rails: four feet, eight and a half inches. Around sixty percent of the world's railways agree on it, down to the half inch. Everyone "knows" why: Roman war chariots, two horses, ruts worn into Roman roads. That story is wrong. The real reason is stranger, nobody ever really chose this number at all. Here's where four feet eight and a half actually comes from, why the Roman-chariot tale (and its famous Space Shuttle ending) falls apart, and how an accident from a north-of-England coalfield became the standard for half the planet.