In railroading, "banking" curves is called super-elevation. All Kato N-scale double-track curves have super-elevation, including (somewhat mistakenly called "easement") pieces to transition between normal and super-elevated track. The "easement" pieces have constant radii, but different radii pieces are compatible with others. I'm not particularly interested in it, since it can be detrimental on curves on grades for longish trains (string-lining). All of my layouts have been on Hollow Core Doors (36x80), and except for an oval, almost any layout necessitates elevation and grades. The only way to create non-super-elevated double track curves is to use two single-track curves (which have more variety in radii and angular span/subtended angle). A functional N scale layout on a piece of plywood (not a full sheet) can also slide easily under a child's twin bed when not in use, and can be slid out easily to use as wanted. Except for a linear, switching layout, HO cannot practically do that. I learned that the hard way as a kid... My first fling with model railroading did not last long. As an adult, I tried N scale, and fell it love with it (once I had replaced the track and locomotive from my Bachman N scale train set, with Kato, Life Like and Atlas).