Where I live, in Minnesota, demonstrates that our model track bed is not deep enough. I used Midwest's Cork Roadbed under my track and while this basically covers the ballasted portion of the roadbed, Most of the time real railroad roadbed is much thicker. I drive by the old Northern Pacific tracks (now BNSF tracks) regularly. The prepared road bed for this section of track was prepared back in the 1800s and the road bed is much thicker than just the ballast! This would be a good place for a manufacturer to come up with a foam road bed for our models to make our road bead more realistic. Something about 1 inch thick would be a great addition to track laying.