I read this article in Wired a few weeks ago, but I keep thining about it whenver I'm walking somewhere:
a central premise guiding American road design was that driving and walking were utterly incompatible modes of transport, and that the two should be segregated as much as possible. ... The psychology of driver behavior was largely unknown. Traffic engineers viewed vehicle movement the same way a hydraulics engineer approaches water moving through a pipe - to increase the flow, all you have to do is make the pipe fatter. Roads became wider and more "forgiving" - roadside trees were cut down and other landscape elements removed in an effort to decrease fatalities. Road signs, rather than road architecture, became the chief way to enforce behavior. Pedestrians, meanwhile, were kept out of the traffic network entirely or limited to defined crossing points. [wired]
The major part of the story is about Hans Monderman, a traffic engineer who favors making roads seem more dangerous so that they'll actually be safer. Pretty cool, and probably a long way off.