The least amount of legs and individual parts, plus ease of building are again the theme to support the peninsula portion of the layout.
The type B bracket is again cut from one continuous piece of 4'x8' plywood, but this type is attached to and supported by one vertical 4"x4" interior grade post. Each bracket and post will support the required number of 2 foot wide shelves respective to that one side of the peninsula on either side of the centered post.
The 4"x4" posts are secured in place at the top by attaching them to the underside of the joist of the floor level above but are only anchored to the floor by the weight of the layout.
Although the temperature and humidity changes little inside the house throughout the year, I do not want the support posts for the peninsula to serve as additional lally columns therefore possibly having an adverse affect to the floor or structure above.
I used a post level to plum the posts to locations marked on the floor , then firmly attaching them at the top to a corresponding location above the drop ceiling were I had bridged two floor joists with a piece of plywood with a shorter piece of 2x4 fastened to it. Before firmly attaching the post to the 2x4, I brushed on white lithium grease to the mating surfaces.
With the post plum and firmly attached at the top, I drilled two 5/8" holes thru the post and 2x4. A length of 3/8" threaded rod was inserted thru both 5/8" clearance holes with a greased washer and finger tightened nut on both sides of the holes to serve as a plus or minus 1/8" slip joint of sorts. This joint to allow any expansion/contraction movement of the layout or structure to remain independent of each other. The original fastener used to position the post was then removed
No adverse affects to the above flooring or structure have occurred during several seasonal changes to date.
The 2' wide type A brackets cost about $14 each, the 4' wide ones about $24 each
The type B brackets about $32 each
This system has worked out well for me and is cost effective for the number of levels that they support. Each one of these bracket assemblies were quick, easy to build and are very strong. They provide a solid surface for the roadbed, a place to hang the lighting fixtures and to secure the backdrop and extruded foam board "sky".