The current layout occupies an 8' x 10' corner of the dining room:

(Plan will be updated in a few days to reflect the new design of the yard.)

This plan is a compromise of dreams and realty.  The dreams of a room filing empire that I would never get running vs an easy to build, scenic and maintain layout that would not conflict with the surrounding space, (um, too much).

Freight trains are made up by hand in the yard to the left.  They travel clockwise and return by backing into the yard.  The tracks in the center will be a passenger terminal which will run a full spectrum of train types ranging from ancient steam to modern Japanese bullet trains.

If all goes well the layout will expand to the right along two walls of the living room.  It would be about 12 inches deep in that area.