Well i have just started the multi-layered monorail type sysyem that will be intergrated above an existing layout below. I am going to run passenger cars only on the upper portion.. 3 sets will run on an oval of an area 4'by 12'. I have 3 engines that will run a c & o articulated steam, penn rr steam, and 1 diesel alaska. I also will be adding a wall rail around the room which an o gage penn will run. This entire system is above the lower layout 3 large trestles and at the doorway to the room a trestle that will be able to raise if needed when entering and exiting. Once done the room will have 13 different sets that can run all at once through mountains over bridges and trestles. Ho--g--and o.