As I'm working on my NKP-ish layout, laying roadbed, I happened to check my plan against physical Atlas code 55 turnouts.
I'm using AnyRail for my planning software.
All the turnouts in Anyrail matches the physical turnouts, except for the curved turnouts.
Atlas says the outer radius is 21.25", and the inner is 15". Anyrail uses these dimensions. (SCARM does the same, near as I can tell). The physical turnouts are different, although I haven't figured out exactly how. I'm pretty sure the effective outer radius is larger than 21.25 though.
EDIT
After some checking, the effective overall inner radius is very close to 16.25". That doesn't mean it's a smooth curve, just that, for track-planning purposes, it will fit where a 16.25" curve will fit.
The overall outer radius is a little squirrelier, but it seems to be close to 23.75".
/EDIT
Anyone have any data on what the real geometry of these curved turnouts is?
And yes, I know hand-laid would be better (and I'd know the geometry). I've used the Atlas curved turnouts successfully before, but not where knowing the precise geometry was so critical.
Anyway, building turnouts is plan C (plan B is to modify my track plan to adapt to the actual turnout geometry, after I figure out what it is).
