SCALE-IT-DOWN REGARDLESS? Where Worlds Collide has further information about Iain Rice's new book on mainline modelling, expanding on my earlier comments. Modellers of all scales might want to bear in mind that, even in the smallest scales, what passes as a "broad" curve would likely have a 30 mph (50 km/h) speed restriction on it in the prototype. (Thus, even the biggest of North American basements is really too small for very fine modelling of a mainline, unless it's the Chicago Rapid Transit you're doing, where a 24" minimum radius is correct in O Scale ... but then you'd have trouble fitting Marshall Field's into your basement, to say nothing of the Board of Trade.) Still sounds like the book is worth a look.
Time permitting, I might be able to work on a project that will feature big O Scale steam power in a space no larger than a ping-pong table. Why? To demonstrate my big power at shows. How? Model an engine terminal. (I know, it's an old dodge, but how often will you see a Pennsy 6-4-4-6 coming on shed and a GWR King going off shed, followed by a B&M 2-8-4?)