If I’m ever going to do it now is the time as there is no scenery yet. This is my model railroad for the next 20 years if I live that long. I don’t ever want to tear it out and start a new one and that helps justify a lower level. I’ll have to relocate the control panel and change some legs. This will be 2 seperate layouts, nothing connecting them. The bottum layout will be the same as the front edge of my top level and narrow as acess will be poor to the rear. I’ll have to lean over it to get to the rear, I will have a removable acess hole. I plan on 32" dia or 16" radius Gargraves to keep it narrow. My top layout is 41" from the floor to the bottum of the joists. I’ll use 1x2 frame with several legs to make it strong. 20" below the bottum of the top joists allows enough room to crawl under it to get to acess opening and wiring repairs. I can do the wiring from the top along side the roadbed while it’s still open.On the Model Railroad forum under Layout building search type double deck and ther are 148 pages although each reply is a new post so advance fast. The scale guys all want a longer mainline so they connect the 2 levels. Also I don’t mind a few 2x2 post’s in the view. I will gain another 38’ loop, and plan on at least one passing siding so I can alternate trains and a reverse. Both top and bottum will be 027 hi rail.
I have seen a few layouts that have large staging / classification yards on a lower level connecting upwards to the second level. Seems like a great idea to store locomotives and rolling stock that are ready for revenue duty.