Editing Roundabout (section)

==History==

=== Origins and demise of traffic circles ===
Circular junctions existed before roundabouts, including:
* 1768 [[United Kingdom]]: The [[Circus (Bath)|Circus]] in the city of [[Bath, Somerset]] was completed. This was constructed based on architectural considerations and not for traffic purposes.
* 1780 (ca.) [[France]]: The [[Place de l'Étoile]] around the [[Arc de Triomphe]] in Paris.
* 1791 [[US]]: [[Pierre Charles L'Enfant]] (who came to America in 1776) designed a [[L'Enfant_Plan|plan of Washington, D.C.]], which was then being planned. This design contained several large places/street crossings. Many of them had a rectangular outer outline, but within each was a place, around which the streets should be built, thus reducing the number of arms/legs of each crossing.
* 1821 US: The Governor's Circle (later renamed [[Soldiers' and Sailors' Monument (Indianapolis)#Monument Circle|Monument Circle]]) of [[Indianapolis]], Indiana (which gave the city the nickname "The Circle City");
* 1877 France: The French architect [[Eugène Hénard]] was designing one-way circular intersections.<ref>P. M. Wolf, ''Eugene Henard and the Beginning of Urbanism in Paris, 1900–1914'', International Federation for Housing and Planning, The Hague, 1969, cited by Ben Hamilton-Baillie and Phil Jones, ''Improving traffic behaviour and safety through urban design'', Proceedings of ICE – Civil Engineering| volume=158 Issue 5 May 2005 p. 41 {{cite web|url=http://www.hamilton-baillie.co.uk/papers/ICE_paper_April05.pdf |title=Archived copy |access-date=10 October 2006 |url-status=dead |archive-url=https://web.archive.org/web/20070730130826/http://www.hamilton-baillie.co.uk/papers/ICE_paper_April05.pdf |archive-date=30 July 2007 }}</ref>
* 1879 [[Netherlands]]: The Keizer Karelplein in [[Nijmegen]].<ref name="Verhoeven">{{Cite book |last=Verhoeven |first=Dolly (red.) |date=2009 |title=De Canon van Nijmegen |location=Nijmegen |publisher=Uitgeverij Vantilt |page=131 |isbn=9789460040351}}</ref>
* 1899 [[Germany]]: Brautwiesenplatz in [[Görlitz]].<ref>{{Cite web|url=http://www.alles-lausitz.de/was-alles-in-goerlitz-erfunden-wurde.html|title=Was alles in Görlitz erfunden wurde – Alles-Lausitz.de|website=Alles-Lausitz.de|language=de|access-date=5 June 2017|archive-url=https://web.archive.org/web/20170807120730/http://www.alles-lausitz.de/was-alles-in-goerlitz-erfunden-wurde.html|archive-date=7 August 2017|url-status=dead}}</ref>
* 1904 US: [[Columbus Circle]] in [[Manhattan]], New York.
* 1905 US: American architect [[William Phelps Eno]] favoured small traffic circles.<br>He re-designed New York City's famous Columbus Circle, which was finished in 1905.
* 1907 US: Architect John McLaren designed one of the first American traffic circles for both autos and streetcars (trams) in the [[Shasta/Hanchett Park, San Jose, California|Hanchett Residence Park]] in what is now [[San Jose, California]].<ref>http://twofeet.weebly.com/walking-blog/the-five-circles-of-hanchett-park The Five Circles of Hanchett Park, 7 June 2014</ref>
* 1909 United Kingdom: The first British circular junction was built in [[Letchworth Garden City]].<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/magazine/3972979.stm|author=BBC News|title=Roundabout Magic|access-date=13 May 2007 | date=2 November 2004}}</ref><ref>{{cite web |url=http://www.letchworthgc.com/cgi-bin/news_fullstory.cgi?newsid=72 |author=Letchworth Garden City Heritage Foundation |title=Sign of the Times |access-date=14 December 2006 |archive-url=https://web.archive.org/web/20061016113507/http://www.letchworthgc.com/cgi-bin/news_fullstory.cgi?newsid=72 |archive-date=16 October 2006 |url-status=usurped}}</ref>

Although some may still be referred to as ''roundabouts'', the operating and entry characteristics of these traffic circles differed considerably from modern roundabouts.<ref name="NAP"/>

Circular intersections were built in the United States, though many were large-diameter 'rotaries' that enabled high-speed merge and weave manoeuvres. Older-style traffic circles may control entering traffic by stop signs or traffic lights. Many allow entry at higher speeds without deflection, or require a stop and a 90-degree turn to enter. Because these circumstances caused a lot of vehicle collisions, construction of traffic circles and rotaries ceased in the 1950s, and some were removed.<ref name="Beldon">{{Cite web |url=https://www.youtube.com/watch?v=AqcyRxZJCXc|archive-url=https://ghostarchive.org/varchive/youtube/20211211/AqcyRxZJCXc| archive-date=11 December 2021 |url-status=live|title=Why The U.S. Hates Roundabouts |author=Christine Beldon |work=[[Cheddar (TV channel)|Cheddar]] |date=17 December 2019 |access-date=18 April 2021}}{{cbignore}}</ref>{{rp|at=3:02}}
<gallery widths="200" heights="160" class="center">
File:South-Yarmouth-MA-US rotary plaque.JPG|[[National Register of Historic Places]] plaque on the first traffic circle in the United States, at the intersection of River and Pleasant streets in [[Yarmouth, Massachusetts]]
File:Thomas-Circle Washington-DC 1922.jpg|Thomas Circle in Washington, D.C., 1922
File:Place Charles-de-Gaulle from the Arc de Triomphe, July 2001.jpg|Traffic ten abreast traverses the ''[[Place de l'Étoile]]''. This traffic circle surrounds the ''[[Arc de Triomphe]]'' at the intersection of ten two-way and two one-way streets. It has no lane markings.
</gallery>

=== 1960s development of modern roundabouts ===
[[File:Letchworth Roundabout 1909.jpg|thumb|The United Kingdom's first roundabout (1909) in [[Letchworth Garden City]]]]
Widespread use of the modern roundabout began when the UK's [[Transport Research Laboratory]] engineers re-engineered and standardised circular intersections during the 1960s. [[Frank Blackmore (traffic engineer)|Frank Blackmore]] led the development of the "priority rule" and subsequently invented the mini-roundabout<ref>{{cite news |title= Frank Blackmore: traffic engineer and inventor of the mini-roundabout |url=http://www.timesonline.co.uk/tol/comment/obituaries/article4131930.ece |archive-url=https://web.archive.org/web/20100524152615/http://www.timesonline.co.uk/tol/comment/obituaries/article4131930.ece |url-status=dead |archive-date=24 May 2010 |work=The Times |date=14 June 2008 |access-date=15 June 2008 | location=London}}</ref><ref name="ourston.com">{{cite news | url=http://www.ourston.com/updates-archive/114.html | title=Leif Ourston receives Frank Blackmore Award | work=[[Ourston.com]] | date=13 January 2010 | access-date=7 October 2013 | author=Ourston Roundabout Engineering, Inc | url-status=dead | archive-url=https://web.archive.org/web/20131029230042/http://www.ourston.com/updates-archive/114.html | archive-date=29 October 2013 | df=dmy-all }}</ref> to overcome capacity and safety limitations. The priority rule was found to improve traffic flow by up to 10%.<ref>Clint Pumphrey. [https://science.howstuffworks.com/engineering/civil/roundabouts1.htm "How Roundabouts Work"]. howstuffworks.com</ref> In 1966, the United Kingdom adopted a rule at all circular junctions that required entering traffic to give way to circulating traffic. A [[Transportation Research Board]] guide reports that the modern roundabout represents a significant improvement, in terms of both operations and safety, when compared with older rotaries and traffic circles.<ref name="NAP">{{Cite book |last=National Academies of Sciences |first=Engineering |url=https://www.nap.edu/catalog/22914/roundabouts-an-informational-guide-second-edition |title=Roundabouts: An Informational Guide |edition=2nd |date=4 December 2010 |doi=10.17226/22914 |isbn=978-0-309-15511-3 |language=en}}</ref> The design became mandatory in the United Kingdom for all new roundabouts in November 1966.<ref>{{Cite web |title=Roundabouts: A Direct Way to Safer Highways {{!}} FHWA |url=https://highways.dot.gov/public-roads/autumn-1995/roundabouts-direct-way-safer-highways |access-date=15 September 2023 |website=highways.dot.gov}}</ref> Australia and other British-influenced countries were the first outside the UK to build modern roundabouts.<ref name="Ourston1995"/>

=== Spread in Europe and North America since 1970s ===
* In 1951, Cyprus, British Crown colony back then, adopted the roundabout in the main cities.
* In the 1970s, [[France]] and [[Norway]] adopted the modern roundabout.<ref name="Kooman"/>
* In 1973, the U.S. city of [[Seattle]] began installing small traffic circles within existing intersections to calm traffic.<ref>{{cite news |last=Hadley |first=Jane |date=22 November 2004 |title=Getting There: Perks for drivers of hybrid cars? Sorry, and here's why not |page=B1 |url=http://seattlepi.nwsource.com/transportation/200597_get22.html |work=[[Seattle Post-Intelligencer]] |url-status=dead |archive-url=https://web.archive.org/web/20041122203835/http://seattlepi.nwsource.com/transportation/200597_get22.html |archive-date=22 November 2004 |accessdate=29 February 2024}}</ref> {{As of|2021}}, the city has installed over 1,200 traffic circles, primarily in residential neighborhoods.<ref>{{cite news |last=Dahl |first=Doug |date=18 January 2021 |title=With a wink and a nod, a quick left often is drivers' go-to move at calming circles |url=https://www.bellinghamherald.com/news/traffic/rules-of-the-road/article248506375.html |work=[[The Bellingham Herald]] |accessdate=29 February 2024}}</ref>
* In 1980, [[Switzerland]] had 19 roundabouts.<ref name="Ourston1995"/>
* In 1980, Norway had 15 roundabouts.<ref name="Ourston1995"/>
*In the early 1980s, single-lane roundabouts (or mini-roundabouts) were also introduced in the [[Netherlands]].<ref name="Kooman"/> It began in the relatively sparsely populated northern and eastern Netherlands because of fears that the roundabouts would not be able to cope with the traffic density of the [[Randstad]]; however, when it appeared the single-lane roundabouts had an even higher capacity than signalised intersections, they were constructed en masse in the western Netherlands as well.<ref name="Kooman"/>
* In 1983, France adopted the yield-at-entry rule on national routes; since then the country's roundabouts have proliferated.<ref name="Ourston1995"/>
* In 1985, Norway put up yield signs at the entries to all its roundabouts. After this, safety and traffic flow rapidly improved,<ref name="Ourston1995"/> and Norwegian roundabouts increased from 15 in 1980, to 350 in 1990, to 500 in 1992.<ref name="Ourston1995"/>
* In 1987, Switzerland introduced the yield-at-entry rule; since then its roundabouts increased from 19 in 1980 to 220 in early 1992, while 500 more were being considered.<ref name="Ourston1995"/>
* In the late 1980s, the Netherlands saw significant growth with about 400 roundabouts constructed in just 6 years.<ref name="Ourston1995"/> Construction accelerated in the 1990s, and by 2001, there were an estimated 1,500 to 1,800 roundabouts in the Netherlands, more than half of which were located within built-up areas.<ref name="Kooman">{{Cite journal |last1=Kooman |first1=Bas |date=March 2001 |url=https://books.google.com/books?id=gJFsyiHOUXIC&pg=PT65 |title=De rotonde. Veilig rondjes rijden? |journal=[[Kampioen]] |volume=116 |issue=3 |pages=65–66 |language=nl}}</ref>
* In 1990, the US constructed its first modern roundabout, although older roundabouts have been somewhat common in parts of the Northeast (called rotaries or traffic circles).
* In 1991, France was building 1,000 roundabouts every year.<ref name="Ourston1995"/>
* As modern roundabouts rose in popularity in the 1980s, the old traffic circles fell out of favour and many were converted into modern roundabouts or other types of intersections.<ref name="Ourston1995"/>
* In 1999, Canada built its first modern roundabout.<ref name="Tollazzi"/>
* As of the beginning of the 21st century, roundabouts were in widespread use in Europe. For instance:
** In 2010, France had more than 30,000 roundabouts.<ref name="Keh 2010">{{cite news |last=Keh |first=Andreh |title=European Import Has Cars Spinning. Heads, Too |url=https://www.nytimes.com/2010/11/19/us/19roundabouts.html |access-date=19 November 2010 |work=[[The New York Times]] |date=18 November 2010 }}</ref>
** There were around 25,000 in the United Kingdom in 2015.<ref>{{cite news | url=https://www.theguardian.com/cities/2015/oct/19/traffic-lights-roundabouts-way-out | title='Traffic lights are so dictatorial' ... but are roundabouts on the way out? | work=[[The Guardian]] | date=19 October 2015 | access-date=13 February 2020 | author=Wylie, Ian}}</ref>

<gallery widths="200" heights="160" class="center">
File:Aangekocht in 1991 van United Photos de Boer bv. - Negatiefnummer 32989 k 6 a. - Gepubliceerd in het Haarlems Dagblad van 15.09.1990.JPG|Roundabout, [[Haarlem]], Netherlands, 1990. Cyclists may also be users of a roundabout.
File:Pacionfi.JPG|Small roundabout in [[Barzio]], Italy
File:Straßwalchen kreisverkehr 2.jpg|Roundabout in [[Straßwalchen]], Austria
File:Colombo Galle Face Roundabout.JPG|Roundabout in the centre of [[Colombo]], Sri Lanka
File:Зеница 20180730 175900.jpg|Double-lane Raindrop Fountain Roundabout in [[Zenica]], Bosnia and Herzegovina, where roundabouts replaced all traffic lights since 2011.
File:Rydsrondellen.JPG|Roundabout signs in [[Linköping]], Sweden
File:British Direction Sign 1.svg|A roundabout sign example used in the UK
</gallery>

=== North American introduction since 1990s ===
{{multiple image
| align             = right
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| image1            = 2020-05-23 11 54 16 View east along Maryland State Route 231 (Prince Frederick Road) from the overpass for Maryland State Route 5 (Leonardtown Road) in Hughesville, Charles County, Maryland.jpg
| width1            = 200
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| caption1          = Modern roundabout in Hughesville, Maryland in 2020
| image2            = Murrayville 01 roundabout.jpg
| width2            = 211
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| caption2          = Modern roundabout intersection in Murrayville, Langley, British Columbia
| caption3          = Roundabout sign in Ontario, Canada
| image3            = Ontario Roundabout Sign.png
| width3            = 145
}}

In the United States modern roundabouts emerged in the 1990s after years of planning and educational campaigning by Frank Blackmore and [[Leif Ourston]], who sought to bring the by then well-established increased safety and traffic flow in other countries to America.<ref name="Beldon"/>{{rp|at=5:03}} The first was constructed in [[Summerlin, Nevada]], in 1990 and was followed by another the following year.<ref name="Ourston1995"/><ref name="roundaboutsusa.com">{{Cite news |last=Wright |first=Lucas |date=18 September 2019 |title=Highlighting the first modern roundabouts in the country during National Roundabout Week |url=https://www.8newsnow.com/news/local-news/highlighting-the-first-modern-roundabouts-in-the-country-during-national-roundabout-week/ |publisher=[[KLAS-TV|KLAS]] |accessdate=29 February 2024}}</ref> This roundabout occasioned dismay from residents, and a local news program said about it, "Even police agree, [roundabouts] can be confusing at times."<ref>{{cite news | first=Dayna | last=Roselli | title=Roundabouts | url=http://blogs.lasvegasnow.com/traffic/2007/04/18/roundabouts/8 | publisher=lasvegasnow.com | date=18 April 2007 |archive-url=https://web.archive.org/web/20120326150503/http://blogs.lasvegasnow.com/traffic/2007/04/18/roundabouts/8/ | archive-date=26 March 2012 | access-date=14 October 2014}}</ref> Between 1990 and 1995, numerous modern roundabouts were built in California, Colorado, Florida, Maryland, Nevada, and Vermont.<ref name="Ourston1995"/>
[[File:Holmen round about.jpg|thumb|Roundabout built in 2023 in [[Holmen, Wisconsin]]]]
Municipalities introducing new roundabouts often were met with some degree of public resistance, just as in the United Kingdom in the 1960s.
* American confusion at how to enter and especially how to exit a roundabout was the subject of mockery such as featured in the film ''[[National Lampoon's European Vacation|European Vacation]]'' (1985).<ref name="Keh 2010"/><ref name=BBC2011/><ref name="Beldon"/>{{rp|at=6:45}}
* A 1998 survey of municipalities found public opinion 68% opposed prior to construction, changing thereafter to 73% in favour.<ref>{{Cite web|url=http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_264.pdf|title=Modern Roundabout Practice in the United States}}</ref>
* A 2007 survey found public support ranging from 22% to 44% prior to construction, and several years after construction was 57% to 87%.<ref>{{cite journal |last1=Retting |first1=Richard A. |first2=Sergey Y. |last2=Kyrychenko |first3=Anne T. |last3=McCartt |title=Long-Term Trends in Public Opinion Following Construction of Roundabouts |journal=Journal of the Transportation Research Board |volume=2019 |year=2007 |pages=219–224 |doi=10.3141/2019-26 |s2cid=110914100 }}</ref>
* By 2011, however, some 3,000 roundabouts had been established, with that number growing steadily.<ref name="Keh 2010"/><ref name=BBC2011>{{cite news|url=https://www.bbc.co.uk/news/magazine-13863498 |title=Is the British roundabout conquering the US?|author=Tom Geoghegan |date=1 July 2011 |work=BBC website|access-date=1 July 2011}}</ref><ref name="Beldon"/>{{rp|at=6:45}}

In the mid-2010s, about 3% of the then circa 4,000 U.S. modern roundabouts were located in [[Carmel, Indiana]], whose mayor [[James Brainard]] had been actively promoting their construction; because of increased safety, injuries caused by car accidents in the city dropped by 80% after 1996.<ref name="Beldon"/>{{rp|at=0:02}} {{As of|December 2015}} there were about 4,800 modern roundabouts in the United States.{{citation needed|date=July 2021}} As an example, [[Washington (state)|Washington state]] contained about 120 roundabouts {{as of|October 2016|lc=y}}, all having been built since 1997, with more planned.<ref>{{cite web |url=http://www.wsdot.wa.gov/safety/roundabouts/washingtons.htm |title=WSDOT – Washington's Roundabouts |date=11 October 2016 |archive-url=https://web.archive.org/web/20161011143946/http://www.wsdot.wa.gov/safety/roundabouts/washingtons.htm |archive-date=11 October 2016 |url-status=dead |access-date=17 October 2018}}</ref>

The first Canadian traffic circles were in Edmonton. There were 7 such by 1954. However, they didn't gain popularity in the rest of the country until the 1990s. They became increasingly popular amongst traffic planners and civil engineers in the 15 years thereafter due to their success in Europe. By 2014 there were about 400 roundabouts in Canada at the time (most in Quebec, Alberta, British Columbia and Ontario), or one per 90,000 inhabitants (compared to one per 84,000 inhabitants in the United States that year).<ref name="Tollazzi">{{Cite book |last=Tollazzi |first=Tomaž |date=2014 |title=Alternative Types of Roundabouts: An Informational Guide |url=https://books.google.com/books?id=qf85BQAAQBAJ&pg=PA110 |location=Cham |publisher=Springer |page=110 |isbn=9783319090849 |access-date=18 April 2021}}</ref>