Thanks to everyone for your kind words and encouragement.
Paul, no, I didn't support the inclines with plywood under the cork. To be honest, I wasn't inclined (sorry!) to do that. Added to that was the thought that if I ever need to re-align that loop, I would have to cut new plywood. I've found that the Atlas track is rigid enough that if I support it about every 6", it doesn't sag even under the weight of a scale-sized die-cast steamer. I found out quickly that supporting it only at the rail joiners was not adequate, so just as quickly I added a riser between every two existing ones.
Mark, you're correct that the room is lower than the entrance door. The original basement's ceiling is under 7 feet. I specified to our architect that I wanted enough height for a full 8' drop ceiling in the train room. The landing is 25" above the floor, and yes it's a great observation point. I took the first and second photos from there.
As an aside, our contractor had to cut through 18" of stone wall to gain me access to the train room from our original basement. My wife and I took an overnight trip to Pittsburgh the day they did that and a similar opening upstairs.
