It will work but you will hate yourself in the morning. Minimum clearance staging areas sound great but the first time you have a problem, its a BIG problem. Plus any wires, switch linkages, scenery, etc on the 1" upper level that protrudes through the bottom of the foam will create an obstruction to the trains below. Any sagging you do get will create clearance or access problems.
Rule of thumb is that you have to be able to reach over a track of cars and pick up a car and remove it. Otherwise if you have a boo-boo on the back track you have to stop everything and clear out ALL the tracks in front of it to reach the back track.
If this is the ONLY way you can structure layout, if its choice between this and not having a layout, then go for it and build the lower level with the precision and quality control of a NASA project. If there is any other way to build the layout, explore those options before you decide.
Dave H.
Dave H. Painted side goes up. My website : wnbranch.com
Basically I'm building a 12' x 12' N scale layout with a second level for hidden staging. The idea is to have it be an G shape and on either end have a 2% grade down to the second level, which will be non-scenic, just storage tracks (I can make trains up on upper level, even in the yard perhaps) and then run them down to staging/storage. I am planning on the top surface of the staging level being 4" below the top surface of the main layout. The crazy idea comes in the construction.
The plan is to use flat shelving for the bottom level, and attach the track directly to the shelving (most likely plywood). WS incline sets will be used to achieve the seperation desired. Where access is needed on the bottom level, (to throw switches in staging yard, and in emergency situations remove a derailment) I was planning on 3" blocks (either wood or foam), which will support 1" foam, that 1" foam surface being the subroadbed for the top layer. Would the 1" foam be rigid enough with the blocks every 12" - 16" or so to support the upper layer? All scenary on the upper level would be foam based so as light as can be.
I'm fairly confident that a 3" gap from bottom of upper layer to top of upper level is enough clearence, unless I missed something? I know it's tight for my hand, but since I'm not actually fiddling with the rolling stock in that space, just removing it if it derails, it is enough. Suggestions? Will this idea work?
Edited for more info: If it matters it runs along 3 sides of the room, and the area that would have the staging yard directly underneath is only 18" deep, the staging tracks would be on the front portion of that. Maybe only four or five deep.