Alotta good points! Yeah, I'm trying to stick to the bent dog bone idea, to avoid the construction of a gate, or duck unders, while maintaining a continuous loop in the SMALL space of the room. I might have to push the yard throat a little more down & to the right to give enough space. Have yet to see how the 20" as opposed to 22" curves turn out. Nothing permanent yet though, my dad is going to lay out 22" curve templates on the floor this spring, and see how it all fits in.
The reason to avoid Jos's idea with the roundhouse to the upper right, is to allow for easy access. The switching should also be up front (yard & industries). I like the way its all planned out, if it was for my use, I'd do something that way, but we gotta remember, my dad is rolling on 72 years of age, on the 22nd of this month. So its gotta be simple, with little reaching, besides the loops...