An "industrial park" is a thought, but I'd tend towards urban industrial, where the tracks have to conform to city streets:
Besides that easily obtainable cutey, I'd stick to VERY small steam engines and VERY small diesels.
I do believe I'd go with something like a 15" minimum radius, and perhaps sharper when feeding a building. Of course, I'd make sure my rolling stock would fit the tight curve. I wonder how sharp the track switches were in these locations. I remember some trackage like this in San Francisco, in The Olden Days, south of Market (kinda near where Millennium Towers is falling over). Very cool!
Rolling stock: 40' long. Or less. Cars used to come in at 36', and etc.
I'd try VERY hard to fit in a loop, because sometimes it's fun just to watch them go.
I'd seriously consider some kind of "clip-on" track extensions, that would extend the trackage a bit, only to be installed on special occasions (actually running trains without guests). No scenery on those, just a bit of "backing up" track--easy to store. Maybe even a micro-yard.
One thing I've seen in street trackage is a track swinging to the right before crossing over itself to make a left turn. Probably have to be hand laid, of course. Something to look forward to???
This could really be fun!
Ed
