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Highways & Autobahns All about automobility



View Poll Results: Which do you prefer?
4-Way stops 28 21.21%
Roundabouts 102 77.27%
Neither 10 7.58%
Multiple Choice Poll. Voters: 132. You may not vote on this poll

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Old June 11th, 2007, 07:48 AM   #1
Alex Von Königsberg
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Roundabout vs. 4-way STOP

Let's talk about the advantages and disadvantages of modern roundabouts compared to 4-way STOP intersections.

Here is an example of a modern roundabout:



How it works:
  • Traffic already on the circle always has the right of way
  • Entering traffic should stop only to yield to drivers already on roundabout, otherwise they must not stop
  • Pedestrian crosswalk can only cross the path of entering/exiting traffic, but not roundabout itself
  • Parking within roundabout is prohibited

Here is an example of a typical American 4-way STOP intersection:



How it works:
  • Traffic from every direction must come to a full stop (even if the intersection is empty)
  • First come - first go basis
  • If two vehicles get to intersection at the same time, the one on the right should go first

Here is how a 4-way STOP intersection compares to the roundabout in terms of conflict points for vehicles:



Conflict points for bicycles:



A typical capacity for roundabouts (vehicles per hour):
  • One-lane: 2500-2800
  • Two-lane: 3500-4000
  • Three-lane: 5,800+

Maximum capacity for 4-way STOP intersection is 1,300 vehicles per hour (need confirmation).

Which alternative would you prefer: all-way stop or roundabout? What is your justification?
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Old June 11th, 2007, 09:04 AM   #2
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Stop signs would provide a society like the US with more arbitrary rules, and it seems like people would follow it better than a constantly moving roundabout.

Accounting for speed variations, less "skilled" drivers might find it hard to enter a roundabout under heavy traffic.

As a tool of traffic, I think stop signs are more useful in preventing accidents, etc. And provide more order by making everyone stop.

Personally, I prefer roundabouts. Sorry if my analysis is flawed, i am tired!
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Old June 11th, 2007, 09:40 AM   #3
Alex Von Königsberg
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However, the statistique shows a noticeable reduction in accidents with introduction of roundabouts. I don't have the numbers with me, but two years ago Sacramento municipal department of road safety provided me with the statistique showing almost 50% reduction of injury-related accidents.

I drove through one that was built nearly 5 years ago and noticed that all drivers feel quite comfortable navigating it. They did not fail to yield nor made unnecessary stops either.
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Old June 11th, 2007, 02:32 PM   #4
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Roundabouts are generally a much better solution, but only if there's not too many of them, especially on main roads; except if 2 (or more) main roads intersect.
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Old June 11th, 2007, 02:45 PM   #5
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in shown occasions - roundabout is better. but at large intersections with roads with more lanes roundabouts are not good because they start to be very confusing. so, for not large crossroads - roundabouts, for large crossroads - traffic lights.
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Old June 11th, 2007, 06:07 PM   #6
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I hate those polls!
Always depends on the kind of road. Available space, amount of traffic (if there's too much traffic, 4-way STOP will be better then a roundabout),...
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Old June 11th, 2007, 07:59 PM   #7
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Here in Wisconsin, WisDOT (the state agency responsible for building/maintaining the state's highways) has a policy to require the study of a roundabout option for ANY intersection on a road under its control if it is due for either reconstruction or new construction and traffic and other indications call for signals. It obviously does not mean that the intersection will become a roundabout, but it is studied. In the instances where they have been installed, including several here in the Appleton area, they have worked VERY WELL and many more are expected in the next few years.

I do like that they offer a free flow of traffic, are self-regulating and cost far less than installing and maintaining signals.

There is a complex intersection here in the City of Appleton (east end of the College Av bridge over the Fox River) where WisDOT engineers studied a two-lane roundabout vs. a redesigned conventional signalized intersection when the bridge is replaced starting next year and they found that the roundabout would cost over a half-million dollars less than the conventional intersection and take 5 or 6 fewer houses.

Amazing.

Are they perfect for every situation? Not in the least, but they most certainly do have a place in the list of options.

Mike
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Old June 11th, 2007, 08:09 PM   #8
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Quote:
Originally Posted by x-type View Post
in shown occasions - roundabout is better. but at large intersections with roads with more lanes roundabouts are not good because they start to be very confusing. so, for not large crossroads - roundabouts, for large crossroads - traffic lights.
true, i prefer roundabouts on two lame roads always over normal junctions but for motorways they are IMO not suitable, in Austria there are roundabouts on motorway junctions, i don´t find that very good.
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Old June 11th, 2007, 08:12 PM   #9
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Is roundabout something new in US? I don't remember seeing a picture of one from US nor Canada.
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Old June 11th, 2007, 09:02 PM   #10
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Quote:
Originally Posted by keber View Post
Is roundabout something new in US? I don't remember seeing a picture of one from US nor Canada.
A "roundabout" per se is relatively new. Those designed with modern features have only been around for 10 years or so here. Antiquated traffic circles are fairly common in the Northeast, though.
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Old June 11th, 2007, 09:15 PM   #11
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Quote:
Originally Posted by radi6404 View Post
true, i prefer roundabouts on two lame roads always over normal junctions but for motorways they are IMO not suitable, in Austria there are roundabouts on motorway junctions, i don´t find that very good.
in Zagreb we have 2 quite large roundabouts, each has 3 lanes and all roads that come there are 6 laned. those places are known as real fear-factor in Zagreb!
also, roundabout at Pesnica, Slovenia is quite messy in that way, or one in Graz near bypass motorway
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Old June 11th, 2007, 09:23 PM   #12
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Roundabouts are much better for numerous of reasons.

-Save energy from traffic lights
-Slow the traffics down
-Reduce pollution
-Safer for cyclers
-More pedestrians friendly
-Traffics can keep going without stopping.
-Almost no accidents

Bend, Oregon has numerous of roundabouts and more new roundabouts are under construction or planned. I believe that Bend is the nations's only city that has more than 14 roundabouts so far. Please correct me if I am wrong. I have pictures of some roundabouts in Bend. I can show here if you guys want to.
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Old June 11th, 2007, 09:24 PM   #13
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Quote:
Originally Posted by x-type
in Zagreb we have 2 quite large roundabouts, each has 3 lanes and all roads that come there are 6 laned. those places are known as real fear-factor in Zagreb!
also, roundabout at Pesnica, Slovenia is quite messy in that way, or one in Graz near bypass motorway
Yes, however the interchange in Pesnica is only half-built, the roundabout was never meant for transit traffic. When fully built, a flyover will be added for the new motorway going past Maribor. But I agree with you, yes, the current situation is very messy, not to mention it serves both local traffic and expressway traffic!

I generally prefer roundabouts, however for a junction with a lot of traffic an intersection with traffic lights or a grade-separated junction would be better.
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Old June 11th, 2007, 09:28 PM   #14
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Quote:
Originally Posted by CrazyAboutCities View Post
-Traffics can keep going without stopping.
-Almost no accidents
ain't no true. at least in Europe.
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Old June 11th, 2007, 09:59 PM   #15
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Quote:
Originally Posted by CrazyAboutCities View Post
I have pictures of some roundabouts in Bend. I can show here if you guys want to.
Post them, please...
I heard Oregon was on the forefront of this here in the US along with Utah and Maryland.
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Old June 11th, 2007, 10:39 PM   #16
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Cool roundabout in Guadalajara (Spain)

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Old June 11th, 2007, 11:49 PM   #17
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Quote:
Originally Posted by x-type View Post
ain't no true. at least in Europe.
That's funny... Before City of Bend installed roundabouts... Bend had numerous of automobile accidents... After they changed it to roundabouts, its reduced the number of accidents dramatically. It only reported two accidents on roundabouts in the last few years... Only two of them are drunk drivers. Bend still have many intersections and still have some accidents but not on roundabouts. Soon all busy intersections in Bend will be replaced with roundabouts within few years from now.
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Old June 12th, 2007, 12:01 AM   #18
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Bend, Oregon Roundabouts with Public Artworks















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Old June 12th, 2007, 12:12 AM   #19
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^ Very nice roundabout! There's a roundabout in my city with accident almost every day.
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Old June 12th, 2007, 12:19 AM   #20
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Thanks. Sounds like they're bad drivers.
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