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Old 03-17-09, 04:15 PM   #1
David13
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Roundabout/TrafficCirle

Somebody posted a definition of a traffic circle and a roundabout that seemed to me to be a distinction without a difference.
I guess there is no difference.
http://www.dot.ca.gov/dist07/travel/...ts/roundabout/
http://www.pe.com/localnews/rivcount...1.46d763e.html
My thought is that they cause more problems than they solve. Namely accidents.
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Old 03-17-09, 04:22 PM   #2
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they're amazing if people know the rules on them - they don't in the USA from what people have told me

and the big ones are not so safe because they're even more dangerous when people have no clue

edit: that roundabout in the picture is pretty safe, we have four lane ones here. I ride on them, but I take the lane and make sure people don't pass me from the right etc.
You should definately only do this if you are comfortable looking around, otherwise it's unmanageable
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Old 03-17-09, 04:29 PM   #3
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Actually, studies have shown that roundabouts are typically safer than other sorts of intersections, and have the added advantage of keeping all traffic moving while calming it at the same time. The one exception, unfortunately, is that they are more hazardous to cyclists. I am guessing that it's because cyclists are generally (1) somewhat unexpected, and (2) harder to notice in a roundabout. In a car, I would always scan the other sides of the roundabout before entering to make sure I am yielding to anyone who's currently in it. A bicycle is smaller and less noticeable. The best thing that can be done is (1) take the lane at a roundabout, and (2) invest big-time in visibility aids such as a headlight/taillight/vests, etc. FWIW, side visibility, talked about on other threads, may be most valuable at a roundabout since people are scanning in all directions. A roundabout that was constructed as a solution to backed-up traffic in town here (Northshore Dr and Concord Rd) has earned high marks after initially drawing much opposition.

A traffic circle is different from a roundabout. IIRC they're typically larger, and have opportunities for people to weave and so forth, and different yielding rules. I'm fairly sure they've been deprecated.
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Old 03-17-09, 04:31 PM   #4
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What gets me is the magic roundabouts.... or a roundabout of roundabouts:



Still, I've driven in England and I agree that they are very, very, very effective at sorting out traffic at intersections that, in the U.S., could only be sorted out with traffic lights. But with roundabouts, when traffic is light, you never have to stop and wait for the light to cycle through.

In England, some roundabouts are supplemented with traffic lights for rush hour traffic in areas where when it is busy it gives all directions a chance at getting through.
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Originally Posted by bragi "However, it's never a good idea to overgeneralize."
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Old 03-17-09, 07:05 PM   #5
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I think yield signs and all-way-stops (possibly all way yield?) would be a great solution - They have way more give way signs than roundabouts in England, and you don't need nearly as much land. We have two all-way-stops between relatively busy rural roads around where I live, and I never have to wait more than 2-3 seconds to get through (even in a car).

Another thing is to get rid of the left turn light at signalized intersections - I don't get why 1 person waiting to turn left gets to go before 20+ people waiting to go straight, when he could just wait for the 20 to pass and then turn.

Also, there should be way more flashing reds on weekends. Traffic lights tend to annoy me incredibly when I'm in my cage...(probably cuz I don't typically obey them on a bike)
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Old 03-17-09, 10:34 PM   #6
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There is a difference in how I interpret them..... I think of traffic circles as small, neighborhood planter circle type of traffic calming device placed in the middle of existing low ADT intersections, and roundabouts as much larger traffic sorting and queing devices built onto arterials and higher ADT thoroughfares- even state highways.

I had a hick in a pickup yell at me to yield to him in a newly minted state highway roundabout out in the sticks despite me having entered it ahead of him. They've been implementing in in the Northwest with some regularity, even the heinously disorienting (in a car) multiple sets of roundabouts in rural-burbia.

Last edited by Bekologist; 03-17-09 at 10:41 PM.
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Old 03-18-09, 08:24 AM   #7
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The rules are the same, whether it's a roundabout or traffic circle. If you are inside the circle, you have the right of way, and those wanting to enter the circle have to yield. The problem is, at least here in Miami, Florida, the drivers don't understand the rules.

It happens all the time that as I am approaching the circle, that cars inside the circle stop to let me in.

Also, it frequently happens that cars that are approaching the circle on multilane, fast-moving roads, think that they have the right-of-way and don't have to yield to traffic inside the circle.

Those are the rules, but unfortunately few who know them or follow them, so be prepared.
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Old 03-18-09, 10:23 AM   #8
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They put one outside my city recently but never gave anyone the rules for it so no one knows what to do.
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Old 03-18-09, 10:47 AM   #9
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Modern Roundabouts

More
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Old 03-18-09, 12:01 PM   #10
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I wish they had done something like that here, people stop going into it, etc.
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Old 03-18-09, 12:04 PM   #11
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http://www.azdot.gov/CCpartnerships/...uts/L202_8.asp
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Old 03-18-09, 12:49 PM   #12
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I'd like it if they replaced arterial street intersections with roundabouts and dropped the speed limit to 25 mph.
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Old 03-18-09, 01:14 PM   #13
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traffic circle vs. roundabout

http://www.camrose.com/engineer/roun...roundabout.htm
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Old 03-18-09, 02:14 PM   #14
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Old 03-18-09, 02:44 PM   #15
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We have them in New England, it is called a Rotary. Easy to use, just put down the cell phone first.
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Old 03-18-09, 08:58 PM   #16
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VDOT is big on roundabouts these days. We're getting a big one in Blacksburg to replace the signal at one of our major intersections. They installed one on the VT campus a couple of years ago, and we'll be getting a few more around town too.

* The biggest safety benefit is that everyone is moving in the same direction, so no deadly head-on or T-bone accidents

* Everyone's going slower so reaction times are adequate

* Traffic keeps moving unless it's really heavy, and it almost always flows better than with a signal

* It's much better for air quality and noise -- vehicles don't sit idling, and they burn less fuel when they don't have to accelerate from a complete stop

The main problem with roundabouts is that they may need more real estate.
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Old 03-18-09, 09:09 PM   #17
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Oh by the way they don't need electricity.
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Old 03-19-09, 01:54 PM   #18
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I like the smaller ones with single lane feeders and one central circular "lane". These slow traffic down enough so it's easy to take the lane and flow through with everyone else.
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Old 03-19-09, 08:08 PM   #19
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Quote:
Originally Posted by mattotoole View Post
The main problem with roundabouts is that they may need more real estate.
Back in my hometown of Omaha, NE, they put in a roundabout/rotary/traffic circle with some, uh, adjustments so that they wouldn't have to take out a gas station and a few houses:

http://maps.google.com/maps?f=q&sour...04565&t=h&z=18

Pic attached.

It used to be that there were three "intersections" -- Happy Hollow and 50th, N Saddle Creek - 50th - Seward, and Country Club-Happy Hollow-Saddle Creek. However, there was only one stop sign in any direction, so, for example, someone driving westbound on Happy Hollow would only stop at 50th before crossing there and the big intersection with Saddle Creek and Happy Hollow. The trouble was, not everybody could figure out where the other stop signs were and how to yield to each other, so you'd have people advancing out of turn or stopping for no reason at all just halfway across.

"The Peanut", as it's been nicknamed, is much better. It also has a lot of signage saying to yield to traffic coming from the left around the nut.

I can think of a similarly large intersection in my neighborhood that would benefit from changing to a traffic circle (or even a "peanut"). Not totally sure how it would affect other intersections nearby, but it would eliminate people having to idle for no cross traffic. Pedestrian crossings would be a puzzle, though.
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Old 03-19-09, 08:11 PM   #20
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And, I agree, not enough people know how to handle roundabouts here. There are a lot in DC that are crippled with traffic signals, nearly defeating the purpose of their existence.
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Old 03-20-09, 11:54 AM   #21
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Quote:
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And, I agree, not enough people know how to handle roundabouts here. There are a lot in DC that are crippled with traffic signals, nearly defeating the purpose of their existence.
no doubt some government official trying to fix a non problem...
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Old 03-20-09, 12:36 PM   #22
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We have three relatively new traffic circles in my neighborhood, and I generally like them because they have very tight radii of curvature, 15mph/25kph design speeds, only one lane within the circle, and yield signs at all four entrances. I strongly oppose multi-lane high-speed roundabouts, because they are deathtraps for bicyclists and pedestrians.
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Old 03-20-09, 03:20 PM   #23
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As a cyclist, the central thing to remember about them is to take the inner lane until you get to your exit, or else you are going to be merging at every entrance and exit you pass. And if you don't get a chance to merge out to your exit, you can just go around again!

Unfortunately, I've heard of some traffic circles where some genius has placed a sidepath for bikes around the outside of the circle, which is exactly where you don't want to be! You'll be in potential conflict at every leg.
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Old 03-20-09, 04:47 PM   #24
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All roundabouts are traffic circles but not all traffic circles are roundabouts.

Quote:
Originally Posted by BarracksSi View Post
And, I agree, not enough people know how to handle roundabouts here. There are a lot in DC that are crippled with traffic signals, nearly defeating the purpose of their existence.
If it has traffic signals or stop signs, it's not a roundabout.
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Old 03-20-09, 09:44 PM   #25
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Roundabouts rock. On my bike I rarely have to even slow down, even at busy intersections. In my car I never have much of a wait.
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