John, here's another version. I reduced the clearance to 6" hoping you'd use 1/2" plywood for the upper level. The major change is that the inner mainline doesn't dip down on the left side. There 2 sets of flex tracks along the bottom to eliminate the "S" curves that were there. I only replaced some of the 12.4" straights with 37" straights, but it's easy enough to replace the rest.
