Roadbed

Now that all of the framework is done, I built the roadbed. Since this is an open framework type of construction with lots of hills, I will not be just covering the framework with plywood.

The first layer of the roadbed is 3/8" plywood. In areas where there are towns or large industries, I just used large pieces of plywood attached directly to the joists of the framework. The roadbed that runs between the towns is just wide enough for double track with an additional 1/4" on each side to allow me to glue the terrain to it.
Making the straight sections is pretty easy. Just use a straight edge to mark the wood and cut it. Making curved sections is somewhat harder.

The first thing I did was to use the 3rd PlanIt program to draw a 3" straight section leading into a curve via a transition track. I then printed this out full size. After taping the sheets of paper together, I cut out the curve and used that to draw its shape on a piece of plywood. I then cut out the plywood and using a red marker marked the transition part of the curve. This plywood curve became my template.
Using this I can quickly make pretty much any curve I want. The 3" template is a used to enforce having 6" of straight track between curves. This prevents S curves that can derail trains. Once I had the template, I cut another template. The two templates can then be placed on top of each other and slid back and forth to create small curves.

Once you have the curve shape you want, you place them on a sheet of plywood and draw out the curve. Then a quick cut and you have a 3" straight, a transition, the curve, another transition, and a final 3" straight.
For larger curves I make two copies of the template, and a curve section using the template but skipping the transition part (which is why I marked it in red). I then clamp these three pieces together. By sliding them back and forth you can make curves of greater than 180 degrees. Once I have the curve I want, I make sure the diameter is correct. This sort of ensures a consistent curve. Then I draw lines on top where the pieces overlap. After I cut at the lines I wind up with three pieces of curve, and two glue blocks.
The parts of the curve that were cut off are used as a glue blocks under the roadbed. I glue the pieces of the curve together, clamp it, then screw the block on using 4 short screws. I can then use the clamps somewhere else while the glue dries. When deciding where to put the glue blocks, I had to be careful not to place them over a joist. This prevents sudden 3/8" hills in my roadbed.
For the next layer of the roadbed I usually use cork from Midwest Products. I used up what I had left and headed off to Neal's N-Gauging Trains. He was out of it. So instead, I bought some Woodland Scenics foam road bed. This is the same height as the cork, though for some reason the widths vary. You lay the foam roadbed the same way as the cork roadbed. However splitting the foam roadbed down the middle is not as easy as splitting the cork roadbed. The foam roadbed can be formed into an 18" radius curve without splitting it, so I have no complaints. I used Elmer's wood glue to attach the foam, mostly because that is what I had on hand. I use small nails to temporarily hold the foam in place while it dries. I will also put weights on the ends as they tend to pop up before the glue dries.

While placing the roadbed we discovered that there was not enough room to work on the hill between the decks if the upper deck is closed up. So we are not going to add joists or place roadbed on the upper deck until the lower deck containing the hill is almost completely sceniced.