Foam with a grade below the track question?

[BR60103]

Are you working with horizontal curves as well as vertical? That makes it more difficult.
I've done a little bit by cutting across 2" foam with a hot wire. What I need for this is a pair of templates, for each side of the foam sheet, pinned to the foam. I haven't come up with anything for the horizontal to grade curve yet -- I think it needs to be larger radius than regular railway curves. The templates also have to be really smooth; even for straight cuts I have to be careful about the grain of the wood and joints between wood bits cause little (or big) jumps.

I gave up this time and just used WS risers, although there are some interesting grade changes even there.

First time I tried them, I "economised" by using 1/2" blue foam layers. Then I fund that the 1/2" was more like 9/16".

You can try to make transitions by flexing a thinner sheet of material between the horizontal and grade. A sharp change at the top can cause couplings on long cars to disengage.