One oddly endearing thing I always forget about when I go to Rochester, until I see it again, is the Inner Loop. This is an expressway that runs tightly around the city's downtown core, presumably built for easy commuter access to downtown. I've done a bit of Googling, and I find that like many such expressways, it's seen as a barrier between the downtown and the outlying neighborhoods, creating an artificial barrier to development or whatnot.
Parts of the Inner Loop are below the normal street level (I'm not sure what the actual term for this is), but if we're worried about the barrier to neighborhoods and streetscapes posed by their crossings of expressways, I'm reminded of a unique solution they did in Columbus, Ohio.
Expressways can be dividers in cities. But there's nothing that says they have to be.
UPDATE: More photos of the Columbus I-670 cap here, from the streetscape level. You literally never know you're crossing an expressway.