Hi Tall J, your plan is off a bit, which makes a difference. The two end-curves should be symmetrical, but yours are at different positions. One mistake I noticed, is that the left side of the inner-route straight-across (bottom-middle), bridging the middle: You have only two 1-3/8" sections, while the plan calls for three (two extra in yellow, and one with the turnout in green).
And it looks like at the other end of that same bridging straight section, there are two 1-3/8" sections and a 1-3/4" section.
I used AnyRail, with the tolerance set tight. So this should work better than you are showing. I spoke with the AnyRail designer, and he actually measured FasTrack pieces and used those values in his software, rather than Lionel's published. Manufacturing variances can cause a difference over a large number of sections. So AnyRail can be very close to actual. See if you can see what section I am referring to, and revise.
Because I was curious, I took apart the design, and re-assembled it with 1/16" tolerance, zero degree difference tolerance, and it assembled perfectly.
I tried the same diss-assemble and re-assemble, with 1/32" tolerance, and a perfect fit, with AnyRail.
Be advised, that your experience "on the ground" might vary a little bit. For instance, I noticed that sometimes two 1-3/8" + one 1-3/4" does not match perfectly with a 4.5" section: Lionel's variation. Or China variation, if you would rather.
