I am planning to build a shelf mounted layout around my condo.
Originally, I had planned to go with HO, but as I researched the requirements for the radius for 85 foot cars, I decided to go with N Scale using minimum 22" radius.
I am planning to have dual tracks side by side most of the way.
My question, how far apart (center line to center line) should the N-Scale track be for 85 foot cars?
You could experiment with a “dry run” on some plywood, or homasote, or foam, etc. – By first spiking down a “90-degree section” of flextrack on a 22" radius. Then tack down flextrack on either side of your 22"-radius flextrack while rolling your longest cars on each track as a 2-track mainline clearance test.
A suggestion is to check out N Scale sectional track radius selection at the Atlas website which is 1.25" on-center.
You will need more track-on-center clearance between cars on curves than on straight trackage. Also then “dry run” experiment with roadbed under the track – There is a potential roadbed “scenery drainage effect” that can be modeled between tracks – Check out your local prototype tracks.
N Scale Code 55 track generally has nicer scaling than Code 80 – Check out each code size – Use what you feel is best. Atlas’ website again is a good starting point.
See the Dave Vollmer’s Layout Expansion thread for visual reference when modeling N Scale on doors.