If you want to see why traffic lights are necessary, wait until hurricane season in the US and come visit whatever city gets smacked hard this year. Trying to get through intersections of major multi-lane streets with no working traffic lights is no fun at all. In fact, in the aftermath of our recent experience with Hurricane Ivan, several local people were killed by drivers who decided to ignore the "treat an intersection with non-working lights as an all-way stop" rule.

On the other hand, roundabouts are mercifully rare here in the States, but judging from my limited experience with them, I can see how traffic signals could just exacerbate problems associated with them. Weren't roundabouts developed as a means of easing traffic-flow in pre-traffic-signal days? Installing traffic lights at some roundabouts would amount to an unnecessary level of traffic regulation when just using the roundabout as originally designed would work just fine.