Roundabouts work by kind of giving priority to the road with the busiest traffic. Once someone goes straight across, the person opposite can also go, and so it continues. Until eventually someone turns left or right, and then the other lanes get a chance to go and establish themselves. It does all work out in the end, trust me. :-) And space-wise, they don't have to take up any more room than a typical US/Canadian intersection, plus there's the bonus of having a pretty flowerbed in the middle of the larger ones - what more could you ask for? ;-)

Traffic lights have the disadvantage that even if there's no-one coming from the other direction, the traffic is still stopped. Plus there's a huge bias against turning across the traffic, which can create serious tailbacks - it's just as easy to go in any direction at a roundabout.

Now 4-way stops, that's a lousy idea...

Graham.