I will be making a layout on a 13'x3'. I want to know if a 16.25" radius will fit. I dont want to buy track and not have it fit in the alloted space. Thanks for all your help. PS I want to go with a 16.25" radius because I will be running autoracks and 8-40's and dont want it to look abnormal on the turns.
I assume this is n scale? 16.25" means a center-to-center 33", leaving probably an inch or so of clearance on each side. That is cutting it close. If you reduce it to 15" radius, that will leave a more comfortable 3" on each side. The difference will be barely noticeable in radius, but your trains will not be at risk of discovering the 9.80 meters-per-second acceleration of gravity to the floor.
Not to split hairs, but 16.25" radius means 32.5" center-to-center. That leaves 1.75" center-to-wall/edge. If your back edge of the layout is against the wall, you could favor the front and push the layout a bit towards the back (ie not centered front-to-back) say about 0.5". That would give you a more comfortable 2.25" on the front edge, and a reasonable 1.25" on the back - where nothing would fall to the floor. Then add some bushes or short trees in front of that to create a block of some kind and you're fine. Another option is to go to flex track instead of the sectional. This allows a custom radius (say 16" or 15.75") to make things as broad as possible without being overly close to the table edge. My layout (which IIRC you based yours on) was planned with 16.25" radius curves but I used flex in the construction. The actual radius as-laid is a shade under 16" - and I didn't favor towards the back as much as I should have (never crossed my mind at the time). The front also has an additional 0.75" added from 1x2s that I used in benchwork construction. Hope this helps.
