Roundabouts on NPR

[US71]

http://www.npr.org/2011/09/28/140877823/going-round-in-circles-over-traffic-fix

Over the past decade, the number of roundabouts in the U.S. has increased dramatically, from the low hundreds up to the thousands. Modern traffic circles can cut down on commute time and pollution. Studies have shown that they even reduce accidents. And many American cities are planning to put in more. But there are still a few roadblocks in the way of a true roundabout revolution.

(Of course, one of those roadblocks is people knowing how to use them  )

[realjd]

"Blood Circle"? Roundabout accidents are so low speed the chance of injury is almost zero. And people's confusion only makes them safer since that makes them timid, defensive, and careful when maneuvering through the circle.

[OCGuy81]

Ha ha.  So true about the people learning to use them.  A few years ago, on my renewal notice, there was a section on the back that was a brief overview on how to navigate traffic circles.  Really?

[corco]

And people's confusion only makes them safer since that makes them timid, defensive, and careful when maneuvering through the circle.

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I have a professor who is pretty high up on the Transportation Research Board and she's 100% convinced that this is why roundabouts are safer

[realjd]

I just made the mistake of reading through the comments on the NPR article. It's full of people from the NE who don't understand that they're NOT the same as a traffic circle or "rotary". That's the biggest hurdle to adoption in the US IMO is people who can't grasp that roundabouts != traffic circle.

[1995hoo]

One of the big problems, at least here in the DC area, is that people think "roundabout" and "traffic circle" are the same thing, and they automatically equate "traffic circle" with the monstrosities in the District of Columbia, which are nothing like modern roundabouts. In fact once when I said "roundabout" someone said, "Oh, you mean TRAFFIC CIRCLES." 

I have some friends who claim to be anti-roundabout and who think four-way stops are better. But they also complain about the price of gas. When I say, "A four-way stop makes everyone stop even if there's no need to do so. You get zero mpg when you're stopped. A roundabout makes you stop only when there's another car coming and you have to yield. How is a four-way stop better?" Usually their answer involves "don't trust other people."

As with many of us, I first encountered roundabouts on a large scale in the UK, and one of the things I picked up is the British convention for using your turn signals in the roundabout. It contains one crucial difference from what American highway departments–or, at the very least, the Virginia DOT–preach. Assuming a single-lane roundabout:

(1) If you're going left (this would be going right in the USA), i.e. taking the first exit, signal left (right in the USA) as you approach the roundabout, yield if needed, and keep your blinker on until after you've exited the roundabout. Americans teach the same method.

(2) If you're going straight, i.e., going beyond the first exit but no more than halfway 'round, don't signal on approach, yield if needed, then put your left (right in USA) blinker on before the exit you want and keep it on as you exit. Americans teach this too.

(3) If you're turning right (left in the USA), i.e., going more than halfway around, signal right (left in the USA) as you approach the roundabout, yield if needed, keep the left blinker on as you go around the roundabout, then signal right as you approach your exit.

Americans don't teach #3. In driving in the UK I found it extremely useful that people did this because it removes ambiguity. In the British system you should see one of three things and they all have distinct meanings: (a) Left signal means "I'm using the first exit"; (b) no signal means "I'm going halfway around"; (c) right signal means "I'm staying on the roundabout." If you omit #3, you're forcing the people waiting at the second entrance to guess as the vehicle approaches as to the driver's intentions–that is, "He's not signaling. Is he taking this exit and just forgot to signal, or is he staying on the roundabout so I have to yield?"

Roundabouts work best when nobody has to guess at what other drivers are doing. I know a lot of American drivers don't like to signal, no doubt sparked in part by rude people who speed up on the highway to keep you from merging. This is the type of thing where a publicity campaign that explains the BENEFIT of using the signal properly in a roundabout might do some good. If I'm waiting at a roundabout and I see you signal right (driving in the USA), then I go because you're telling me you're leaving the roundabout and I need not yield to you.


The thing that amuses me the most is how the 'fraidy-cats bleat endlessly about how roundabouts will bring a parade of horrors and then after they're in place most people say how wonderful they are. VDOT replaced a traffic light at Gilberts Corner with a system of four roundabouts and everyone out there says how much faster it is getting through that intersection now.

To me part of the appeal of a roundabout is that it's the opposite of the traditional American philosophy. I think a lot of American traffic law is based on the idea of "in some situations, you might have to do X, so we'll make you do X all the time." A four-way stop is like that. Some traffic lights that don't use traffic sensors and instead just use a fixed cycle are also like that, at least when they're outside of urban areas. The roundabout says, "You can go unless you're required to stop and yield." The driver is trusted to know the rules and to know when he has to stop and yield. That scares the crap out of a lot of people because Americans are used to always being told exactly what to do in all situations. One of the first things I noticed driving in the UK is how they have FAR fewer regulatory signs than we do, and then I noticed how they have far more "Give Way" ("Yield") signs compared to stop signs whereas we do just the opposite. Of course I also know they have far stricter driver's ed and licensing requirements, and that's a whole different debate, but as someone who's always taken such things seriously I found it very refreshing.

[Michael in Philly]

I just made the mistake of reading through the comments on the NPR article. It's full of people from the NE who don't understand that they're NOT the same as a traffic circle or "rotary". That's the biggest hurdle to adoption in the US IMO is people who can't grasp that roundabouts != traffic circle.

So explain the difference, please.  (I know there is one; there's a lengthy thread on it on skyscrapercity.  But damned if I know what it is....)

[1995hoo]

I just made the mistake of reading through the comments on the NPR article. It's full of people from the NE who don't understand that they're NOT the same as a traffic circle or "rotary". That's the biggest hurdle to adoption in the US IMO is people who can't grasp that roundabouts != traffic circle.

So explain the difference, please.  (I know there is one; there's a lengthy thread on it on skyscrapercity.  But damned if I know what it is....)

You could say that roundabouts are a subset of a larger category of circles. All roundabouts are traffic circles, but not all traffic circles (or "rotaries") are roundabouts. The following isn't intended to be exhaustive, but rather a bit of an overview.

The primary difference has to do with the design and the speeds of traffic. "Traffic circles" generally have approaches that run tangent to the circle and are designed for entry and exit at full speed. Traffic entering the circle often has to merge (think of how the loop-around ramps on a cloverleaf require a weave area–a traffic circle's tangent approaches work similarly in terms of entering and exiting traffic having to cross paths). In a multi-lane traffic circle, entering traffic may have to yield only to traffic in the outer lane (although I know of at least one circle where traffic already on the circle has to yield to any entering traffic), whereas on a roundabout entering traffic has to yield to everyone. Generally to exit a traffic circle you have to change lanes to the outer lane, whereas on a roundabout you can usually exit from any lane. Roundabouts are generally smaller than traffic circles and are designed to be navigated at slower speeds.

The roundabout uses yield-on-entry and expects you to position yourself in the correct lane before you enter (in the case of a multi-lane roundabout) because you're not supposed to change lanes on the roundabout, whereas traffic circles may require you to change lanes several times (try driving through Washington Circle in DC if you're brave). Pedestrians are not allowed on the central island. Many "traffic circles" in DC use stop signs and traffic lights and also allow pedestrians to cross to the island. I've seen a very few traffic-light controlled roundabouts in the UK (one big one in Bristol that I drove through can be seen in the Wikipedia article on roundabouts).

[Michael in Philly]

^^I grew up in New Jersey, which has had "Circles" since the dawn of time.  Roundabouts, until recently, were (to me) just the British word for that.  I have noticed roundabouts/small traffic circles proliferating in exurban areas of Maryland and Virginia recently (on Sunday, I got off the Baltimore Beltway at Reisterstown Road, needing gas, and decided it would be more interesting to continue up to Hanover and York, then take US 30 home than to get back on the Beltway...  Which brought me through Manchester and Hampstead for the first time in a couple of years... there's a new bypass of one of those towns - forget which - with roundabouts at both ends).  When I'm a pedestrian in DC I hate Dupont Circle, because unless you're walking along Connecticut - and can thus cut through the circle - you've got two lights at every little intersection and they seem to be timed against pedestrians, so it can take what feels like ten minutes but is probably three or four to get from one segment of New Hampshire Avenue to the other.

The one in Bristol:  are you thinking of the infamous "Magic Roundabout" in Swindon, which is a bit east of there?  http://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

Anyhow, as far as I can tell, you can't go wrong by yielding on entry so whether it's a roundabout or a circle doesn't actually matter.  But I shall now dutifully educate myself by reading said lengthy thread on skyscrapercity:  http://www.skyscrapercity.com/showthread.php?t=254301

[realjd]

I just made the mistake of reading through the comments on the NPR article. It's full of people from the NE who don't understand that they're NOT the same as a traffic circle or "rotary". That's the biggest hurdle to adoption in the US IMO is people who can't grasp that roundabouts != traffic circle.

So explain the difference, please.  (I know there is one; there's a lengthy thread on it on skyscrapercity.  But damned if I know what it is....)

Traffic Circle / Rotary - Large, high-speed, merge in and out to exit, sometimes circulating traffic yields to entering traffic depending on the design.

Roundabout - Small, entering traffic yields, low speed.

http://www.dot.ca.gov/dist3/projects/yolo16_kentucky/documents/RndTrafficCircle.pdf
http://www.alaskaroundabouts.com/mythfact1.html
https://www.nysdot.gov/main/roundabouts/background

[formulanone]

I'm all for them, but the only danger (and this usually from old folks) is when people come to a complete stop for them, even though there's nobody coming in any direction. We don't have the rotary thing in Florida (or probably much of anywhere in the South). They're also lots of fun if the road has light to no traffic on it (sorry, we don't have mountain roads around here).

Dangerous? I've never seen anything more than a mere fender-bender at a roundabout; never seen any serious accidents at all in or around one.

[1995hoo]

....

The one in Bristol:  are you thinking of the infamous "Magic Roundabout" in Swindon, which is a bit east of there?  http://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

No, definitely not. I've driven through the Magic Roundabout as well (on the same trip, actually; en route from Heathrow to Bristol I detoured into Swindon specifically to see the Magic Roundabout, then headed south to see Stonehenge). The Magic Roundabout does not have any stop signs nor traffic signals. The one I'm thinking of in Bristol is east of the river and is shown below. In fact when I drove up to it I suddenly said, "Hey, this is the one on Wikipedia."




BTW, I did indeed use the inner anti-clockwise circulation on the Magic Roundabout. I quite enjoyed driving through it as a traffic solution, but I'm not naive enough to think it would ever work in Washington DC in place of Dupont or Washington Circles. If they ever DID try it, though, I'd be the first person to get myself down there (via the subway!!!!) with a video camera to watch the carnage.

Anyhow, as far as I can tell, you can't go wrong by yielding on entry so whether it's a roundabout or a circle doesn't actually matter.  But I shall now dutifully educate myself by reading said lengthy thread on skyscrapercity:  http://www.skyscrapercity.com/showthread.php?t=254301

Actually, you can. Memorial Circle in DC (at the west end of Memorial Bridge) requires traffic already on the circle to yield to traffic entering. That's because the highest volume of traffic just passes through two "corners" of the circle (if that makes sense–basically most of the traffic is making two 90-degree turns that briefly touch the circle). The speed limit is 25 mph but a lot of people are approaching at 45 to 50 mph. If you stop to yield on entry, the least that will happen is a massive amount of horn-honking and middle-finger gestures. I might well be one of the people honking and giving the finger!

Satellite view here. You can drag the Street View man to see where the yields are if it's not apparent from the satellite view.

http://maps.google.com/?ll=38.885588,-77.05943&spn=0.001597,0.004128&t=k&z=19&vpsrc=6

[Michael in Philly]

....

The one in Bristol:  are you thinking of the infamous "Magic Roundabout" in Swindon, which is a bit east of there?  http://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

No, definitely not. I've driven through the Magic Roundabout as well (on the same trip, actually; en route from Heathrow to Bristol I detoured into Swindon specifically to see the Magic Roundabout, then headed south to see Stonehenge). The Magic Roundabout does not have any stop signs nor traffic signals. The one I'm thinking of in Bristol is east of the river and is shown below. In fact when I drove up to it I suddenly said, "Hey, this is the one on Wikipedia."




BTW, I did indeed use the inner anti-clockwise circulation on the Magic Roundabout. I quite enjoyed driving through it as a traffic solution, but I'm not naive enough to think it would ever work in Washington DC in place of Dupont or Washington Circles. If they ever DID try it, though, I'd be the first person to get myself down there (via the subway!!!!) with a video camera to watch the carnage.

Anyhow, as far as I can tell, you can't go wrong by yielding on entry so whether it's a roundabout or a circle doesn't actually matter.  But I shall now dutifully educate myself by reading said lengthy thread on skyscrapercity:  http://www.skyscrapercity.com/showthread.php?t=254301

Actually, you can. Memorial Circle in DC (at the west end of Memorial Bridge) requires traffic already on the circle to yield to traffic entering. That's because the highest volume of traffic just passes through two "corners" of the circle (if that makes sense—basically most of the traffic is making two 90-degree turns that briefly touch the circle). The speed limit is 25 mph but a lot of people are approaching at 45 to 50 mph. If you stop to yield on entry, the least that will happen is a massive amount of horn-honking and middle-finger gestures. I might well be one of the people honking and giving the finger!

Satellite view here. You can drag the Street View man to see where the yields are if it's not apparent from the satellite view.

http://maps.google.com/?ll=38.885588,-77.05943&spn=0.001597,0.004128&t=k&z=19&vpsrc=6

That picture from Bristol is actually a good illustration of the problem with saying that the difference between a roundabout and a circle is that one's small and the other's large:  it's subjective.  That looks "large" to me.

Few people know that the west end of Memorial Bridge is actually in DC!

Is there signage for traffic at that Memorial Bridge circle to tell entering traffic that they have the right of way?

[NE2]

'Roundabout' is a marketing term, like 'light rail'.

The one issue I see with roundabouts is if drivers refuse to yield to crossing pedestrians.

[1995hoo]

....

Is there signage for traffic at that Memorial Bridge circle to tell entering traffic that they have the right of way?

You mean something like "Traffic on circle must yield" or "No yield required at circle"? No. The traffic on the circle has large yield signs in addition to the rows of triangles on the pavement, and the usual advance signs that say "Yield to traffic on circle" are not present as you approach from the south or over Memorial Bridge. I suppose I could see why someone might assume there would be a yield, but on the other hand, if you're driving through there, especially if you're coming over the bridge, the design is such that it doesn't promote yielding by entering traffic.

While it's unconventional to set up the yield in the fashion used there, this is one circle where it makes sense because the VAST majority of the cars don't go around to the west side of the circle, which primarily serves Arlington Cemetery. There are a couple of ramps from the GW Parkway and VA-110 that connect to Memorial Drive and that as such require people to pass through the circle, but the volume of traffic is considerably lower. I think what it really boils down to is that the spot was designed as more of a park and wasn't originally intended to become the massive commuter route that it is now.

[NE2]

There are some in New Jersey (e.g. NJ 34 at CR 524) that are like that as well, with the main route getting right-of-way.

[jjakucyk]

Many older traffic circles/rotaries have been modernized to some extent over the years.  The main thing is changing the right-of-way rules so that entering traffic yields to traffic already in the circle.  This prevents the circle itself from ever locking up, but there's usually still other geometry problems.  Some of the circles in Washington DC, ad well as many of the older rotaries in the northeast are simply too large.  No matter what else you do, that makes traffic going around the circle move too fast, so you need much larger gaps for waiting traffic to merge in.  This significantly reduces capacity and causes backups on the approach roads.  Truly modern roundabouts can in many cases be built, including much of the approach aprons and pedestrian crossings, entirely inside the island of an existing traffic circle/rotary.  That shows just how big of a disconnect there is between the existing and the ideal situation.

[mgk920]

Wasn't the circle on I-587 (Kingston, NY) recently replaced with a modern roundabout?

Mike

[1995hoo]

Wasn't the circle on I-587 (Kingston, NY) recently replaced with a modern roundabout?

Mike

You are correct. That one also has "bypass" lanes that allow someone turning right to pass by without actually entering the roundabout (except at the southeast corner). I've seen that design a number of times and I like it, where there's space of course.

[jjakucyk]

Right turn bypasses are really only viable if there's no pedestrians.  Roundabouts are a bit of a mixed bag for pedestrians (and cyclists) to begin with, but the bypass lane is always discouraged when people who aren't driving cars need to be accommodated. 

[1995hoo]

Right turn bypasses are really only viable if there's no pedestrians.  Roundabouts are a bit of a mixed bag for pedestrians (and cyclists) to begin with, but the bypass lane is always discouraged when people who aren't driving cars need to be accommodated. 

I don't believe I suggested it should always be included even if space exists. I simply said I like the design when there's space.

[J N Winkler]

Worth linking here since some of the same issues were previously discussed:

https://www.aaroads.com/forum/index.php?topic=5177.25

[Brandon]

"Blood Circle"? Roundabout accidents are so low speed the chance of injury is almost zero. And people's confusion only makes them safer since that makes them timid, defensive, and careful when maneuvering through the circle.

Low speed?  I usually try to take them at full speed (depending on the speed of the road).  My only problem is with idiot public works departments that fail to understand that stop signs and roundabouts don't mix.

[Bryant5493]

Low speed?  I usually try to take them at full speed (depending on the speed of the road).  My only problem is with idiot public works departments that fail to understand that stop signs and roundabouts don't mix.

Here's a great case in point:

Redwine Parkway SW @ Tinsley Way SW - Atlanta, Georgia


Be well,

Bryant

[on_wisconsin]

What about something like this:

WIS 124/ WIS 178 Intersection in Chippewa Falls, WI
http://www.bing.com/maps/?v=2&cp=44.921140617899745~-91.38043081760392&lvl=17&dir=0&sty=a&where1=Chippewa%20Falls%2C%20WI&form=LMLTCC

There is a south bound thru lane that totally bypasses the intersection.
(Pre-2009, the junction was an old 60's style trumpet interchange. BTW)