Dave, is this a fair representation of the room and layout space? You mentioned 2.5' on the 5' side and 6' on the bridge side as well as being able to access all sides, but didn't say how much. I changed the curves in the upper right to O54 so they'd stop before the opening where the 45" bridge (green) will be. Given that the 5' side is already built, the bridge would straddle it and will have plenty of support on that end. I took out the crossover switches, but kept the 4.5" center-to-center clearance. The top tracks can be moved down 1.75" and the bottom tracks can be moved up as much as 7.25". Because the blue line will still have straights leading into and out of the bridge, the engine overhang should clear on both ends, but you'll have to test that to be sure.
