Not sure if roadbed is the right term or not. I was thinking of something to put between the track and my OSB table top. I couldn't find cork board locally so I was going to use 1x3 strips. It will look ugly on the curves, so I thought perhaps I would just cut sections large enough to support/span the joint between each piece. This would result in an "elevation" of the track by about 1/3" and a gap between each support.
Would this be unadvisable? Would give me a way to secure the track without using too much wood and then worrying about ballast after.