[Bilbo Baggins]

Here's the snopes link for that "urban legend" about the Space Shuttle, railroad gauges and chariot wheels. Hope it's helpful.

http://www.snopes.com/history/american/gauge.htm

Blam and farmfriend, thanks for the GGG posts and bumps.

[farmfriend]

You are welcome.

[aruanan]

I don't believe things are as tidily dealt with as Snopes would like to believe. Somewhere I have correspondence with an author who was working on this very question with respect to a particular gauge of train track in Europe. I'll see if I can dig it up. It was on another computer in another lab, but I've saved all my data, so it's probably there somewhere. I know I've seen it once or twice since then while looking for other stuff.