Shown with Peco Code 80 flex track laid on top.

Cork road bed shown laid as intended with bevel on either side of the ties. Note: secured with staples on plywood.

Shown using only half pieces of cork road bed stapled in place on plywood. I fervently recommend this way.

Note how the Atlas flex track completely covers the cork road bed allowing ballast to create the fall instead of the beveled cork.

I believe that using only half pieces of cork road bed creates a superior fall. Note the trough between the rails that could not have been accomplished with full pieces.