Hmmmm... I may have a stupid idea for my layout to get it to a double-deck.
Green line would be a flat loop line that I'd add spurs from to service various towns. The eventual plan would be to run a single line either under the layout, or off the right end, curving under the Electrical Panel Box, and then have it spread to a yard, keeping an aisle for access to the panel.
This is a proof of concept sketch, nowhere close to a final design. The purple line may weave through a few scenes to make visual separations between them.
The pink/purple line would be a 4% grade to get elevation on the layout, then circle around a mountain, and take off about 8 or so inches above the layout. If I continue the incline with cookie-cutter ply attached to backdrops brackets, I can gain another 10 inches by doubling back towards the Right end of the dogbone. A false backdrop flap could hide the second half of the climb from the mountain to the upper deck.
I know I've seen that method of long incline, but can't remember if it was in a magazine, or on a youtube layout tour?? Anyone remember?
Caveats: Yes, I know 4% is a steep grade. But I envision the upper deck with smaller curve radii than the lower deck which has 18" radius throughout. So smaller train length to do the back and forth between levels would need to happen anyway.
Now, I just need to figure out how to make the lower level more interesting. My main goal is building scenes, with a small ability for one-man operation.
Thoughts and suggestions are welcome.