Thanks! It fits inside of a 2x4 rectangle. At its narrowest points, (in the middle) it is only 20" wide. (The depth of my desk) I used Kato track and it is completely 9 3/4 radius track. The full turns are 45 degree pieces while the s-curves where made with 15 degree pieces (although 30 would have worked) Even though it is tight and has four s-curves I had never had any problems running anything that I own on it. I have had SD70Mac's and auto-max's and double-stack containers running on it, although now I main run either my gp38-2 or GP20's on it.