Having concluded as to what I wanted on this layout, I set about purchasing the timber, and brackets required to support the five modules I reckon would suffice.
My main feature is "Camden to Narellan Level Crossing" (the Old Hume Highway), then "Bow Bowing Creek to Campbelltown".
The module construction consists of 75mm x 25mm maple frames and 5/16" Ply on top. I said I would not use ply again, as it give off a drumming sound, but the weight factor came into it, and so I decided to go with the noise. Another factor is, I need a lot of flat surface for scenery, and it would not lend itself to open frame. I will be the only one who will have to put up with the noise anyway. I may be able to kill some of the drumming sound by gluing 50mm x 20mm timber cross braces or polystyrene under the ply where possible.
All things considered, it helps you change your way of thinking.
The fixing of the brackets to the wall was no problem, as this purposely designed room is all steel frame, and hexagon head metal self tappers, are the "ants pants".
The roller door was replaced with a 1.8 meter glass sliding door
during the manufacture of the framework by the supplier.
Cheers for now.