Benchwork Design Requirements
My plan was to create a double deck layout that would allow unobstructed storage under the lower deck, a reasonable amount of space between levels and an upper deck set at a reasonable height for me to properly view operations.
I also wanted the lighting for the upper and lower decks to be consistent so I followed the lead of the local club I belong to (grmrhs.org) and planned for the lower deck to be lighted by fixtures under the upper deck and the upper deck to be lighted by fixtures in a light valance above the upper deck.
These requirements suggested light weight, thin profile benchwork for both the upper and lower deck.
My benchwork design was inspired by an article from long ago in Model Railroader about bookshelf benchwork. The author used C shaped plywood pieces on either end of two 14 deep panels that formed a top and bottom. The bottom was used to support track and scenery while the top was a book shelf. He used slotted adjustable shelf supports to mount his benchwork to the wall.
I chose to fasten horizontal furring strips to the wall to provide a place to attach my own E shaped support brackets. These brackets support 2 foam on 1/4 Masonite panels which form the base for the scenery and track sub-roadbed.
Helix Or No Helix?
While a helix is the most common way to connect the two decks, I intended to use an operating incline to raise and lower cars from one deck to the other. However after having difficulty constructing and operating the incline I decided that running trains between decks would be more fun, but only if I could avoid a multi-turn helix.
Back at the drawing board I found that by climbing a 2.5% to 3% grade out of Arcadia to Harbor Junction, a distance of 41 the height was about a third the distance I needed to get to Hill Camp. I then needed only a one turn helix to go the remaining distance and if I planned it right I could turn that into a positive. The descent into Eagle Harbor on the main from Harbor Jct. is an easy 2.5%.
To accomplish all this it was necessary to deviate from my original construction plan for the lower deck. The foam on plywood base was replaced by L-Girders made of 1 X 2 lumber attached to cleats mounted on each side of the joists that extend from the wall. Then joists and risers in the normal fashion for Lgirder construction were fastened to the girders. 3/4 Oak Plywood was then cut to match the curvature of the track and fastened to the top of the risers.
For the flat areas of Arcadia and Eagle Harbor I acquired several second hand 2 X 4 pieces of Sievers open grid benchwork. Making the construction of the Arcadia & Betsey River Railroad quite a mix of modified L girder, open grid and special purpose benchwork styles.