Track standards for larger scales

They sure do. And they have gauges that have little short steps on them to handle superelevation on curves, and ones that have ways to handle the widening of gauges on curves as well.

Erik, please don't go to any trouble on my account. I certainly didn't doubt you, I was just rather intrigued by the idea of measuring centre to centre. But the way you explain it it *sort* of makes sense! ;-)

And I've since found reference to it in one of my own books. As someone else noted, it's just one of things that just is...

All the best,

Mark.

I've found a reference to the French 1500mm centre-to-centre gauge in a Danish booklet from 1984, "Fra skinne til skinne" (From rail to rail) by Povl Wind Skadhauge, but i'm certain that I've seen it somewere else in an older book.