From a traffic engineer in the US
- Roundabouts are safer than either signals or stop signs, UNLESS you're a bicyclist or pedestrian.
- Roundabouts work best when traffic volumes are distributed evenly among the approaches.
- Roundabouts can only be used on relatively flat terrain.
- Roundabouts can't handle as many cars as a signal. When a roundabout gets congested, it acts as a de facto four-way stop.
I'd say that roundabouts are generally preferable to four-way stops, but there are several conditions that would interdict their use. They're also excellent for traffic calming (slowing people down), acting as a transition between a freeway and a local road, and solving accident problems.
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Originally Posted by PonyPotato
Roundabouts are actually practical with different types of traffic, Baraka (and the rest of you). Small roundabouts are ideal for intersections where there is a large flow of traffic on one of the roads, and lighter traffic on the other road.
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This is the opposite of what you want. If the volumes differ greatly, it's more efficient to grade separate the approaches and build an interchange.
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Originally Posted by BadNick
roundabouts...errr, they call them "traffic circles" around here and they are slowly disappearing  |
A traffic circle is not a roundabout! Roundabouts are a very specific type of traffic circle.
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Originally Posted by bagatelle
They've been building them everywhere here in Finland as well. The problem is, in many places they are too small and it causes trouble for long vehicles. Otherwise I like them, they make difficult crossings easier to get through than traffic lights. But our traffic is very modest compared to other countries.
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The circle should have truck aprons, usually made of brick or concrete, for trucks that can't make it completely around.
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Originally Posted by Spiritsoar
The only real roundabout that I've had trouble with is the one around the Arc de Triomphe in Paris. That place is nuts.
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That's because there are no approach or lane markings. Locals tend to have no problem, but if your'e not familiar, don't bother.