The inside loop has an O-27 curve on one end (on both tables near the door entry) and an O-31 on the other end. The middle loops are a combination of O-31 and some O-42 curves. The outer loops are O-42 with a couple of O-54 curves. It's a mish-mash of stuff cobbled together to make six operable, individual loops, each powered by an individual power supply. There are no cross-overs, turn-outs or isolated sections. I had envisioned an O-72 loop, but once the tables were built, it became apparent that the O-72 was not to be. My goal was to have three separate loops on each side of the room. There may yet be an elevated loop at the fireplace end of the room, but I am still not sure I want to embark on further building.
The room is 17 1/2 ft. by 13 1/2 ft. The tables length are just over 17 feet. The ends by the door are 4 x 4 and the ends by the fireplace started out as 5 x 5 but I cut off one corner to achieve the diagonal. The finished table height is 29".