N-scale layout with the center and top boards removed for tunnel viewing. I can stand up in the center of the layout to work on it. The tunnel is covered by train tracks that run in to a 3 track spur. The layout front is risen to 1 1/2 inches and the tunnel has 3 inches of clearance for doublestacks. 2 mainlines go around the layout twice in a figure8 reversed inside itself. The plywood is cut (cookie cutter) style with risers every foot.