A friend of mine came up with the idea of a scenic barrier. He had several staging tracks representing distant cities. To hide them from view, but yet leave them accessible, a scenic barrier provides the illusion of distance. It's a very simple solution, but when operating, it really does work. The barrier strips were made from 1/8" Masonite hardboard, but really any kind of thin sheet of wood would do. The top gets trimmed to give the illusion of mountain top or hill ranges. I cut the rough shape of the Masonite sheet on the table saw to the desired length. The photo below is of a piece approximately 50 inches long, with one end needing to be about 7 inches tall, sloping to about 4 inches on the other end. The dimensions are, of course, dependent on how it is going to be used on the layout. After clamping the piece to my workbench, I free-handed the top edge of the barrier with a 1/4" cross-cutting bit in my router. Moving slowly and holding the router steady, I moved in a random, wavy motion.
This is an example of a scenic barrier.
For ease of installation, I cut two small blocks from leftover wood. I pre-drilled them for a wood screw, and then used yellow carpenters glue to glue them to the barrier strip.
Before, or after, installation, painting the scenic barrier a nice green color will give the illusion of wooded hills. Installation is straight-forward; just use a screwdriver to guide the screw into the layout base. It can be removed if access to the rear tracks is needed. This photo shows two of them installed near the back of the layout, hiding several "staging" tracks.