Southern Pacific Switching Layout

[Gary S]

As it is with the 1/2 inch foam, I can carve drainage ditches along the track in places and contour the terrain slightly.

That is the best reason to use foam. I've mentioned before, but many small terrain features go down, not up. Especially if you are modeling an area that is basically flat. The foam allows you to escape the "plywood pacific" look, as you can carve ditches along the railroad right-of-way, and along roads too. Slight dips can be carved here and there, helping to get rid of the flatness of the plywood. I highly recommend it, even if all that can be found is 1/2". I'd double them up and make 1" thick foam.

Certainly there are tons of great layouts built directly on plywood. But I sure am glad I went with foam to model the flatness of Houston, but perhaps that is because my layout contains not only industrial areas, but rural areas too which need ditches and such. For an ISL, the plywood will probably be fine, as evidenced by some of the great work seen on Big Bue.