
Mythbusters does the 4 Way Stop Vs Roundabout - kposehn
http://www.youtube.com/watch?v=OvoFjirrgYA
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bane
I finally got a chance to visit a couple roundabout heavy countries this past
year and absolutely love them.

Growing up in the U.S. 4-way stops are terrible congestion sources, nobody
follows the rules (right of way), and it's generally an irritating experience
with all the stopping and going. In my local area there are two interesting
stretches of road, on the first there are three close proximity 4-way stops.
Traffic is always messed up on them.

In the other stretch, there used to be an intersection with only a stop on the
access road and then a 4-way lighted stop. In the evenings, traffic heading
towards the intersection would back up for 10 miles or more and take an hour
to cross the intersection. They decided to replace both intersections with
three roundabouts and _poof_ , they haven't had a traffic issue in years
despite more than tripling the number of cars on the same road.

American's still don't do them quite right, they're usually too tight or we
put lights all over them defeating the purpose. In a proper roundabout
country, they're amazing, traffic moves pretty steady, everybody knows what's
going on, they don't really ever feel threatening and if you miss your exit
it's a pretty easy trip round back to it.

I think at some scale level, they start not to work as well as the American
solution though (big highway exits and interchanges). Some of the really large
ones I drove through _were_ more problematic in terms of getting traffic
through, even if navigating was still better. The American method moves more
traffic, but at a loss of driver clarity in many cases.

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dmak
For people who just want to know the results:

385 cars in 15 minutes for the 4-way intersection

460 cars in 15 minutes for the roundabout

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shirro
Roundabouts can be too big or too small. The worst types are the retrofitted
ones in tiny inner suburban streets installed as hazards to slow through
traffic and the huge ones on massive lopsided intersections with more than 4
exits where you can't see the other side. Inbetween on light to moderate
traffic intersections they are absolutely brilliant. They are a floral
centerpiece at the heart of some Aussie country towns.

One problem with them is that the large well functioning ones maximise the
traffic through the intersection and drivers maintain a lot of their speed. It
can be very difficult for a pedestrian to cross at them, particularly with
children, compared with a traffic light.

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jakozaur
Nice show!

Also the research shows that roundabout are much safer:
[http://www.ite.org/traffic/documents/CCA99A33.pdf](http://www.ite.org/traffic/documents/CCA99A33.pdf)

[http://www.ce.udel.edu/dct/publications_files/Rpt.%20199%20R...](http://www.ce.udel.edu/dct/publications_files/Rpt.%20199%20Roundabouts.pdf)

Quote: "In instances where roundabouts have replaced other types of
intersection control, the benefits in terms of safety have been remarkable and
many examples can be found in the literature."

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kt9
Roundabouts also become more efficient when you add additional lanes like they
do in Australia. Stop signs work best only on single lanes of traffic and
things break down if there is more one lane per side.

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chris_wot
Don't Americans have roundabouts?!?

Anyway, curious about which has more accidents.

~~~
Randgalt
Yes, they are called "traffic circles" here.
[http://en.wikipedia.org/wiki/Traffic_circle](http://en.wikipedia.org/wiki/Traffic_circle)

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jacques_chester
So, a few days ago, I drove in the USA for the first time.

Until then I'd never seen a 4-way stop. I never knew such a thing existed.

It took me a while to work out what the heck to do. As an Australian I am used
to one direction having stop signs, meaning that the other direction has right
of way.

But then I come across stop signs in both directions and I've suddenly got
people in other cars looking at me expectantly while I try to work out what
the hell I am meant to do.

We have roundabouts in Australia and yes, they are definitely smoother.

