@NJCJOE posted:...I was leaning towards using 3/4" plywood for the roadbed. There are a few local cabinet makers that sell 3/4" cabinet grade plywood cut-offs in like 8" to 10" widths by 40" long. Maybe these would be useful, but probably not for the curves....
1/2" ply is plenty, and it's easier to bend than 3/4" on the grades. Depending on the distances you're spanning, 3/8" might suffice.
Two approaches... Lay down a full sheet, trace an outline of your track, and cut with a saber saw (known as the cookie-cutter method) - uses more wood, but leaves flat areas to support buildings and accessories. Or cut "sectional" pieces from the plywood and splice them together - less waste, but more splices.
My current layout doesn't have any grades, but I've used cookie cutter with 3/8" ply on a couple of small layouts. Sorry, no construction pics.
