I've finally started to do the residential area behind the Hoovertown business district. As with the business district I want to do the work off the layout, so the first step is to make a removable support structure. Once the support structure is completed, I'll remove it from the layout and place it on my work table to add the streets, landscape, structures, etc.
I wanted something light and easy to work with, so I opted to try for the first time PVC lattice. I know that it's expensive compared to wood, but I like that you can bend sharp curves (using a heat gun) and that using the standard PVC primer and clamps can work very fast. For you engineer types this may look over-engineered and you are probably correct. I never claimed to be an engineer!
The next step will be to add a 2" thick foam top to the PVC base and then add individual foam pieces to get the contours I want. As you can see in the back left of this picture where the track crosses over itself there is a big change from in track heights around this area. So, basically the foam top of this area will have to be built up more on the left and even more in the left rear.
More pictures to come as I progress.