My new layout is based on Wabash Railroad operations in Ontario, Canada during the 1950s. Building a new layout is an adventure. Particularly when an old layout is in the way. Some clever planning was required to get things to a point where work could progress forward. 2 new walls were built to support the layout sections in the middle of the room.
The layout levels are all supported on commercial shelf brackets. A fast and simple solution. The basic benchwork is then a 1 x 2 framework which rests on top and then 1/2" plywood subroadbed and Homasote roadbed. Here are some photos from the construction phase.