During the urban highway craze, things that even today we would have thought to be insane, were done. Neighborhoods were destroyed or divided from the rest of the city. Waterfronts were cut off. Projects which just barely didn't happen - such as the destruction of the French Quarter in New Orleans - should serve to remind us of the projects which did happen.
Still the presumption is that urban highways are necessary, even if we try to consider kindler gentler ones. But they aren't necessary. London doesn't have them, and it hasn't vanished from the map yet.
