3 pcs for 1 corner.
Measuring mine, it is exactly 57 1/2" diameter from the edge of the roadbeds. For a corner, you would need to come out 17" from the center of the corner at the wall, so the apex of the curve would stay on your shelf. (Your walls meet and make a 90 degree angle. If you come straight out at a 45, you need to come out 17 inches to keep the track on the shelf)
You could always lay it out in SCARM, it's a free program, and figure out your measurements!
Good luck!
