@Obsidian (and others)
Your layout designs have been the inspiration for the layout I hope to construct this year. In particular, I've attached one of the designs you shared for another forum member a few years ago that features a 'dog bone' design with three concentric curves at one end (which I believe were perhaps 81, 72 and 63 or 60" curves).
In my attempt to recreate the track plan with Ross Custom track (84, 72 and 64 diameters), I've had the challenge of transitioning from a 4" spacing on the straightaways to a broader spacing that would be (a) required as a matter of course due to the different radii, but also that (b) might allow for additional clearance necessary for longer locomotives or passenger cars.
I've attempted this in Scarm and in Railmodeler Pro with the offset or 'set parallel starting point' command to align the spacing on the curves. It seems to me that I'm forced into some sort of elliptical pattern rather than a constant curve.
Is it as simple as the fact that I believe your plan was created with atlas track (with what I assume to be: (81, 72, 63 curves)? The spacing on your straightaways in the plan would not appear to be as wide as 6" but I could be misreading based upon the 1' grid.
I'd welcome insights from all as to how best I might achieve a similar geometry (3 concentric curves of track, with 72 as the mid-range diameter, and a fairly tight spacing on the straightaways (4" - 5").
Thanks to all in advance,
Scott