Talk:Traffic circle

first in the US

First traffic circle in the US: "Mass. drives to remove rotaries" and Columbus Circle - --Costoa 23:42, 20 March 2006 (UTC)

merge

Maybe not necessarily merge them-but keep a link at the top for 'see also 'traffic cirlce' Mcode 15 June 2006

Canberra

you cant realy say that canberra has traffic circles per-say, because looking at vernon circle from above, you can see that is is closer to being connected chicanes. also, there is the fact that most of the roads in canberra are designed in a way that you can circle around. I also believe that there are probably much more well known traffic circles. --Alphamone 05:20, 12 June 2007 (UTC)

Oldest Circle?

I'm not exactly sure the listing for oldest circle is entirely acurate. There are plenty of older traffic circles around. Among others, Pierre L'Enfant's original street plan for Washington, D.C. has several circles designed and built in the 1800's —Preceding unsigned comment added by 69.251.87.52 (talk) 00:46, 26 October 2007 (UTC)

Indeed. The circle in Tallmadge, Ohio was apparently built in 1807, "modeled after New England designs of the time period" according to this source found at the above-linked article: History of Tallmadge, Ohio -- JeffBillman (talk) 17:13, 4 May 2008 (UTC)

Restrict definition of "traffic circle"?

Some people consider that all roundabouts are traffic circles, but not all traffic circles are roundabouts. Maybe some people do informally use the term "traffic circle" for modern roundabouts in the US, but the term isn't used like that in any official publication that I can find. I believe that the term "traffic circle" is not officially used for modern roundabouts because "traffic circles" have such a bad reputation. So... I've deleted this sentence from the intro: "In some traffic circles, entering roads are controlled by stop signs or traffic signals. In other cases, traffic enters the circulatory roadway by merging, sometimes at relatively high speeds." Anyway, the subsequent sentence covers the same territory better sice the term "traditionally" does not mean "always": "Traditionally, traffic entering a circle has the right-of-way, although some circles give right-of-way to the primary roads."--Farry 13:30, 31 October 2007 (UTC)

Sort-of reply here: Talk:Roundabout#Merge revisit. —DragonHawk (talk|hist) 03:17, 25 November 2007 (UTC)

Merge material

Rotary is being merged here; for the time being I will drop some of that content here:

MakeBelieveMonster (talk) 04:06, 21 February 2010 (UTC)

Merged back into the article. -- Beland (talk) 18:49, 10 July 2010 (UTC)

Urban traffic circles versus highway traffic circles

Currently, there are two types of traffic circle included in this article, but the opening paragraph only defines one of them. It mentions large diameters (over 100m) and small deflections, so that a high driving speed (over 50 kph) can be maintained. But the first picture (Columbus Circle) and at least the first five examples given later on are of a very different type of circle, still with a large diameter, but within a dense urban setting and with 90 degree deflections, requiring entering traffic to come nearly to a stop before entering the circle. For this reason, and also with traffic lights at many of these urban circles, it is too sweeping a statement to say that traffic in a circle usually has to yield to traffic entering. I replaced that statement with a more nuanced one, but I realize that it is still lacking. I think the opening paragraph needs to state more clearly the two types of circles counted in this article (neither of them being roundabouts) and then state in some manner that rules of right-of-way vary between and within the two types. Any suggestions? --Ken Gallager (talk) 12:47, 25 August 2010 (UTC)

Merge with roundabout

What is the point of separating them? I'd pick Roundabout as the article title. Lfstevens (talk) 02:24, 13 December 2011 (UTC)

There is no clear difference between a roundabout and this term 'traffic circle' which I have never encountered in the UK --130.88.99.220 (talk) 16:45, 17 October 2012 (UTC)

On the contrary there are clear differences between traffic circles, roundabouts and rotaries although the definitions of each do vary depending on jurisdiction. Check out the new references I added in my recent edit. 24.19.89.134 (talk) 23:32, 14 June 2014 (UTC)

Merging is very controversial. See Talk:Rotary (intersection). --Iloilo Wanderer (talk) 01:56, 12 August 2014 (UTC)

However, I am in favor of the merge. I think the only major difference between the word "roundabout" and "traffic circle" is preference.LakeKayak (talk) 19:19, 6 January 2017 (UTC)

Mention the worlds largest traffic circle

Mention the worlds largest traffic circle, preferably in its own section. If there is no undisputed one, mention that fact instead. Jidanni (talk) 12:45, 16 November 2012 (UTC)

I think it's Copeland Circle in Revere, Mass. 6/10 of a mile in circumference. https://maps.google.com/maps?hl=en&ll=42.430089,-71.017814&spn=0.003338,0.006968&sll=42.430695,-71.015625&sspn=0.006676,0.013937&oq=240+beach+st&t=h&mra=mr&z=18 Bellczar (talk) 05:00, 28 November 2013 (UTC)

(Rotary intersection) Merge

From what I understand on this subject, a Rotary is just another name for a traffic circle and roundabout. It does not make any sense to have this article, as it is a duplicate. 117Avenue (talk) 03:44, 6 July 2009 (UTC)

Undecided Per the references, there are subtitle yet important differences. However, in common usage, the terms are so intermingled that one long article may make more sense. CSZero (talk) 07:34, 6 July 2009 (UTC)

Recommend Strongly Against It's true that in common usage, the terms are used somewhat interchangably, particularly depending on the region. However, the operations are fundamentally different between the three types. The only commonality is that there is a circular central island. I agree the three articles could use some streamlining and cleanup. However, roundabouts, traffic circles, and rotaries are definitely not the same thing, and this article is definitely not a duplicate.Bigfitz79 (talk) 18:46, 17 August 2009 (UTC)

If you know the difference between a rotary, traffic circle, and roundabout, could you please edit these three articles to give better clarification on what they are, and how they differ. Thanks 117Avenue (talk) 23:29, 17 August 2009 (UTC)

There is already a section within each of these three articles that explains the differences from the other two types. There is always room for improvement with any article, but what about these explanations did you find confusing or unsatisfactory? The wording of your first post on this thread suggests that you had not yet read any of them.Bigfitz79 (talk) 23:03, 19 August 2009 (UTC)

The article Roundabout interchange continues to confuse these terms and either needs to be clarified or is proof that these should all be the same article on "circular interchanges." CSZero (talk) 14:41, 20 August 2009 (UTC)

Ahhhh... I had never seen the roundabout interchange article. You are correct, it could use quite a bit of cleanup and correction. I'll try to tackle that one in the next week or so.Bigfitz79 (talk) 13:52, 21 August 2009 (UTC)

An interchange is different than an intersection, in that it has grade separation. I have a problem with the three different types of circular intersections. However, if you are going to work on the roundabout interchange article, I suggest that it be clear a dumbbell interchange is more like a diamond interchange, not a roundabout interchange. 117Avenue (talk) 00:28, 22 August 2009 (UTC)

Agreed and done. Also modified diamond interchange article to better incorporate dumbell interchanges. There is no "rotary interchange" article, so I moved the examples that were rotary interchanges to the rotary intersection article. I'd like to do some more work on this article, but does this address the concerns/questions you had?Bigfitz79 (talk) 03:24, 24 August 2009 (UTC)

Support merge - They are merely different names for the same thing. Any minor differences can be explained in subsections of the main article. EuroSong ^talk 18:13, 4 December 2009 (UTC)

Merge Rotary (intersection) with Traffic circle; keep Roundabout separate. The fundamental distinction is whether the right of way is given to traffic in the circle or traffic entering the circle. For roundabouts, the entering traffic must yield; for a rotary/traffic circle the traffic in the circle yields. (Source: [1] pg 5. There are also numerous examples of "traffic circle" and "rotary" being used interchangeably.) This is a common source of confusion that these articles don't explain well. MakeBelieveMonster (talk) 20:23, 17 January 2010 (UTC)

Also, I am noticing a good deal of material that incorrectly uses the term "rotary" for intersection where entering traffic has a yield sign. I still think we should use the correct engineering terminology, but the distinctions need to be heavily emphasized. MakeBelieveMonster (talk) 21:08, 17 January 2010 (UTC)

Hearing no objections, I'm executing the merge. The article was enormously inaccurate, and the only source even using the term "rotary" was the Massachusetts Driver's Manual. (Even it acknowledged the more common term "circle.") R.I.P. MakeBelieveMonster (talk) 04:14, 21 February 2010 (UTC)

Thanks for getting this done, I haven't had the time. 117Avenue (talk) 07:42, 21 February 2010 (UTC)

Hold on Sorry, I missed this merge request discussion. Now we have a huge issue. A rotary, as was described in the Rotary article that no longer exists, now says a traffic circle gives priority to those entering the circle. Throughout the entire New England area where the term "Rotary" is usually used, this is exactly the opposite of how they work. You yield to traffic already in the circle. So, now how do we rectify this? I agree that the differences between traffic circles and rotaries are often small, and the terms are often interchangable. But, this has to be cleared up because the "enormously inaccurate" article, now being gone, has left another article enormously inaccurate. CSZero (talk) 06:19, 22 February 2010 (UTC)

Actually, I know what the solution is. We do what the cited source here says (http://www.tfhrc.gov/safety/00068.pdf) and just strip out any references to who has the right of way. We do the same thing for the Roundabout article. If traffic circles and rotaries are the same thing, then traffic circles, as the citation provided states, can work either way. CSZero (talk) 06:30, 22 February 2010 (UTC)

I'm sorry, I'm obsessing but I want this to be right. In addition to this article not being correct about yielding to entering vehicls, only the outermost lane being able to exit from a traffic circle is also false. I can list (and did somewhere in the past) numerous rotaries in the Greater Boston area where two lanes exit. I drove on one just this weekend: http://maps.google.com/maps?ie=UTF8&q=alewife+brook+parkway+cambridge+ma&fb=1&gl=us&hq=Alewife+Brook+Parkway&hnear=Alewife+Brook+Parkway&cid=0,0,8262774192789487595&ei=IiaCS8_6LoO3lAeoi9WCBw&ved=0CAcQnwIwAA&ll=42.38835,-71.143263&spn=0.001561,0.002411&t=k&z=19 CSZero (talk) 06:40, 22 February 2010 (UTC)

What you're describing (entering drivers yield to those in the circle) is a roundabout, at least by engineering definitions. The problem, it seems, is that in common language the terms circle/roundabout/rotary get thrown around interchangeably. But (as you said) the right-of-way distinction is really important. I'll try to add something to the article addressing this. MakeBelieveMonster (talk) 02:20, 23 February 2010 (UTC)

Well, it's already there in the end of the lead... MakeBelieveMonster (talk) 02:42, 23 February 2010 (UTC)

But it still isn't that simple. If it was, the section on why roundabouts are superior to traffic circles no longer holds water, because we are talking about roundabouts of a much larger size, and the articles state that speed and deflection is the issue. Per your own US government citation (the entire paper is here: http://www.tfhrc.gov/safety/00-067.pdf) [emphasis mine]:

Rotaries are old-style circular intersections common to the United States prior to the 1960’s. Rotaries are characterized by a large diameter, often in excess of 100 m (300 ft). This large diameter typically results in travel speeds within the circulatory roadway that exceed 50 km/h (30 mph). They typically provide little or no horizontal deflection of the paths of through traffic and may even operate according to the traditional “yield-to-the-right” rule, i.e., circulating traffic yields to entering traffic.

Section 1.5 continues:

Some traffic circles require circulating traffic to yield to entering traffic.

and the glossary:

rotary—a term used particularly in the Eastern U.S. to describe an older-style circular intersection that does not have one or more of the characteristics of a roundabout. They often have large diameters, often in excess of 100 m (300 ft), allowing high travel speeds on the circulatory roadway. Also known as a traffic circle.

roundabout—a circular intersection with yield control of all entering traffic, channelized approaches, counter-clockwise circulation, and appropriate geometric curvature to ensure that travel speeds on the circulatory roadway are typically less than 50 km/h (30 mph).

So yes, you are correct on the merge, but the citation does not support the claims that traffic circles cannot have yield signs for entering traffic, or that there can only be one lane exiting.

Per this definition, from a reliable source, a roundabout is ONLY an intersection that meets these criteria:

• Yield control for all entrances
• Channelized approaches
• Counter-clockwise circulation
• Appropriate curvature, keeping speed below 30 MPH.

Let's go back to the areal photo I put in earlier: http://maps.google.com/maps?ie=UTF8&q=alewife+brook+parkway+cambridge+ma&fb=1&gl=us&hq=Alewife+Brook+Parkway&hnear=Alewife+Brook+Parkway&cid=0,0,8262774192789487595&ei=IiaCS8_6LoO3lAeoi9WCBw&ved=0CAcQnwIwAA&ll=42.38835,-71.143263&spn=0.001561,0.002411&t=k&z=19

• Yield control for all entrances? Yes
• Channelized approaches? Yes
• Counter-clockwise circulation? Yes
• Appropriate curvature, keeping speed below 30MPH? Well, the intersection is barely 100 feet wide, well below the mentioned "often above 300 feet in diameter" traffic circle description. But - there is almost zero deflection around the circle the way the ramps enter and exit (plus the circle's diameter is not so steep as to force you to drive slowly), so this one is a No, making this a Rotary or Traffic Circle. It's close to a roundabout though it seems.

Another that was put in recently:

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=main+street+and+daniel+wester+highway,+nashua+nh&sll=42.738975,-71.458216&sspn=0.006209,0.009645&gl=us&ie=UTF8&hq=main+street+and+daniel+wester+highway,&hnear=Nashua,+NH&ll=42.738855,-71.45823&spn=0.001511,0.002411&t=k&z=19

Barely 50 feet wide, has raised pavement to accommodate large trucks. Better deflection, slower speeds. Roundabout.

Last one:

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Roosevelt+circle,+medford,+ma&sll=42.738855,-71.45823&sspn=0.001511,0.002411&gl=us&ie=UTF8&hq=&hnear=Roosevelt+Rd,+Medford,+Middlesex,+Massachusetts+02155&ll=42.429143,-71.103119&spn=0.00312,0.004823&t=k&z=18

Here is your classic monster death-rotary. 300 feet across (oblong), zero deflection - not a roundabout, therefore a rotary/traffic circle. Multiple lanes on, multiple lanes off. Traffic entering yields to traffic in the circle.

My suggestion is that we remove these claims about entry/exit requirements and stick to the citation's claims about it being all about speed differentials and geometry.

Thanks for reading all that! CSZero (talk) 04:30, 23 February 2010 (UTC)

Okay, I added some of this detail to the article. The description of yield rules was also modified with "typically." Feel free to add more detail to the article if you think it's needed.

I should add that while I think Roundabouts: An Informational Guide is a great source, its definition of traffic circles as "circular intersections that aren't roundabouts" isn't very useful. (The report is mainly dismissing them, and rightfully so.) But I haven't seen any sources that actually focus on describing rotaries / circles themselves. MakeBelieveMonster (talk) 06:25, 23 February 2010 (UTC)

OK, I made a series of changes to both Traffic Circle and Roundabout. I'm happy now. What do you think? CSZero (talk) 15:36, 23 February 2010 (UTC)

Looks good! MakeBelieveMonster (talk) 23:49, 23 February 2010 (UTC)

(Rotary intersection)"unpopular"

Given that there is no discussion of what it means for a rotary to be "unpopular," and given the NPOV policy, I will remove the discussion of the "unpopularity" of rotaries unless someone can produce some statistics from opinion research. (My own impression is that, like driving on the highway, people dislike rotaries when they first learn to drive and later adore them.) 134.174.140.216 (talk) 21:18, 9 July 2009 (UTC)

I'm not sure what research can be found (and you are correct to be looking for it) but rotaries being converted to different styles of interchanges are certainly commonplace today, and I believe there is a PDF attached to this article from a state civil engineering board that bashes them. It should probably say "unpopular with planners" either way. Thanks, CSZero (talk) 21:56, 9 July 2009 (UTC)

CSZERO - the linked study is only an evaluation of the benefit of "modern roundabouts" (i.e., that angle traffic to slow it down). Little about rotaries, doesn't even include the word "unpopular". I take it you approve, although it may be that some professional association of engineers or urban planners has a stance, maybe we could put that instead. 134.174.140.216 (talk) 05:05, 10 July 2009 (UTC)

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