Hm... yes. LION tried thaat. Track nails will not stick in a foam base. I tried that, I figured all I needed was for the tracks not to slide. So the nails held the track just fine until I got the idea to use reed switches for my signal control. It was a simple matter to put magnets under the cars...
... and pull up all of the nails. Not a bproblem if you glue down your ballast, but the LION does not do that either.
LION used SUPER MAGNETS salvaged fro old hard drives.
Magnets wook good, but are so strong that they interfere with the operation of the locomotive motor.
So yeah, the foam is cheap, but also cheap is accoustic ceiling tiles or sound proof underlayment used for flooring. The underlayment is quite a bit like Homasote but cheaper and easier to cut.
Oh Well. Thems is the ideas of the LION, your wildebeest may vary.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
That foam would give you the opportunity to carve out a creek, or a ditch, or any other ground features that would be below track bed level.
It's also easier for setting trees, pole, etc.
If you plan on having none of that, then there's no reason for the foam.
Mike.
My You Tube
I just finished building the benchwork for my layout using 1 x 4 with a 3/8 partical board top. Was planning on gluing 1" thick pink insulation foam board on top of the particalboard then laying track on that. Since my track plan is flat and wont be going below the cork roadbed is it even worth it to mess with the foam?
This is the latest track plan. A little different then the one I orginally posted in the easement post.