To Mike W's question - here's some messing around I did with the SCARM program. This has never been built, so there are definitely un-resolved clearance issues. It was my first attempt with many layers added, which explains the weird-looking engine-house roof. The main layout is O42 curves and switches; space for the main section is about 4.5 x 12 feet. The elevated section is O27 for a trolley line.
On the plan, the main line disappears off to a return loop off-picture, (trackplan lower right) but it might be possible to squeeze the standard oval in at the left. There are a couple of dead 'tracks-to-nowhere' to give the wide outside world illusion. Notice the cut-out by the enginehouse for the operator's belly.............
