As promised, here are the pictures of Packrat Paul's fine spline roadbed.
Here is only a very small view of Paul's monster mushroom style layout. You can see the smooth flowing lines of the roadbed. This is its big advantage.
This photo shows the underside of the roadbed along with a feeder wire. This material is easy to drill but long term cutting of Masonite will quickly dull drills and saws. Note the 1x4" riser. I agree with Paul in that it is a bit wide.
Here you can see the roadbed under construction. This is a narrow gauge line, hence less boards.
Here you can see the splines separating to form the split for a turnout. The flat edges were made with a belt sander.
The close up reveals how each board is nested into the other. There are two pre-drilled holes for screws that hold the roadbed to the riser.
When you come to a flat area, like this mine section, Paul slices the board in to, then runs just one spline board through the middle. The roadbed spline is the same height as cork roadbed.
Thanks Paul for letting me shoot your fine layout and run a train!