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#REDIRECT [[Roundabout]]
{{redirect|Rotary (intersection)|other uses of Rotary|Rotary (disambiguation)}}
{{Distinguish|Roundabout}}
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[[Image:ColumbusCirclefromTimeWarnerCenterNYC20050807.jpg|thumb|300px|[[Columbus Circle]] in [[New York City]]. Unlike a modern roundabout, the circle is quite large and pedestrians have access to the center island. Access is controlled by [[traffic light]]s.]]
A '''rotary''', sometimes nicknamed a '''traffic circle''', is a type of [[junction (road)|intersection]] that directs both turning and through traffic onto a one-way circular roadway, usually built for the purposes of traffic calming or aesthetics.<ref>{{cite web|url=http://www.vtpi.org/tdm/tdm4.htm|title=Online TDM Encyclopedia - Traffic Calming|publisher=}}</ref> Contrary to a [[roundabout]], where entering traffic always yields to traffic already in the circle and merges in directly, the entrances to traffic circles are 3-way intersections either controlled by stop signs, traffic signals, or not formally controlled.<ref>[http://www.fhwa.dot.gov/publications/research/safety/00067/000671.pdf U.S. Department of Transportation: ''Roundabouts: an Informational Guide'' para 1.5]</ref> Colloquially, however, roundabouts are sometimes referred to as circles.<ref>{{cite news |title=Salem Four Corners traffic circle to start rounding into shape |last=Johnson |first=Jeffrey A. |url=http://www.theday.com/article/20120806/NWS01/308069969/1044 |date=6 August 2012 |newspaper=[[The Day (New London)|The Day]]}}</ref>


{{Redirect category shell|
In the [[United States]], traffic engineers typically use the term '''rotary''' for large scale circular junctions between [[Limited-access road|expressways]] or [[controlled-access highway]]s. Rotaries typically feature high speeds inside the circle and on the approaches.<ref>[http://safety.fhwa.dot.gov/intersection/roundabouts/presentations/safety_aspects/short.cfm U.S. Department of Transportation: Safety Aspects of Roundabouts presentation]</ref>
{{R from alternative name}}

{{R from merge}}
In [[New England]], traffic circles are generally called rotaries and the traffic that is already driving in the rotary always has the right of way. For examples of where this is specified, in [[Massachusetts]] "Any operator of a vehicle entering a rotary intersection shall yield the right-of-way to any vehicle already in the intersection.".<ref>[https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXIV/Chapter89/Section8 ]</ref> In [[Rhode Island]] entering vehicles "Yield to vehicles in the roundabout." <ref>[http://www.dmv.ri.gov/documents/manuals/Driver_Manual_FINAL.pdf ]</ref>
{{R mentioned in hatnote}}

Distinct from roundabouts, traffic circles and rotaries may also have an interior lane that requires traffic on it to change lanes in order to exit the circle.<ref>[http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa10006/ U.S. Department of Transportation: ''Technical Summary: Roundabouts'']</ref>
{{toclimit|3}}

[[File:DeSoto Fountain in Coral Gables 20100321.jpg|thumb|300px|DeSoto Fountain sits in the center of a traffic circle in the [[Coral Gables, Florida|City of Coral Gables]], [[Florida]]. The arterial, DeSoto Boulevard, has unrestricted right of way, while the intersecting streets are controlled by stop signs.]]

==Design==
Design criteria include:

* Right-of-way&mdash;whether entering or circling vehicles have the right of way. The [[New Jersey]] Driver's Manual recommends that, in the absence of flow control signs, traffic yields based on "historically established traffic flow patterns",<ref>http://www.state.nj.us/mvc/manuals/chap_04_06.html</ref> and there are no set rules.<ref>http://www.state.nj.us/mvc/pdf/Licenses/Driver%20Manual/Chapter_4.pdf</ref> In [[New England]],<ref>{{cite web|url=http://www.mass.gov/rmv/dmanual/index.htm |title=Sharing the Road: A User's Manual for Public Ways |author=Commonwealth of Massachusetts, Registry of Motor Vehicles |accessdate=2009-05-13}}</ref> [[Washington, D.C.]] and [[New York State]],<ref>:http://www.safeny.com/rowa-vt.htm#1145</ref> entering traffic yields, as is the norm in virtually all countries outside of the U.S.
* Angle of entry&mdash; Angles range from glancing ([[tangent]]ial) that allow full-speed entry to 90 degree angles ([[perpendicular]]).<ref name="ModernRoundabouts">{{cite web|url=http://www.fhwa.dot.gov/publications/research/safety/00067/index.cfm|title=Index - Roundabout: An Informational Guide, June 2000 - FHWA-RD-00-067|publisher=}}</ref>
* Traffic speed&mdash;High entry speeds (over 30&nbsp;mph / 50&nbsp;km/h) require circulating vehicles to yield, often stopping, which lowers capacity and increases crash rates compared to [[modern roundabout]]s.<ref>{{cite web|url=http://findarticles.com/p/articles/mi_qa3734/is_200703/ai_n18755716/pg_1 |title=A Comparative Evaluation of the Safety Performance of Roundabouts and Traditional Intersection Controls |author=Shashi S. Nambisan, Venu Parimi |date=March 2007 |work=Institute of Transportation Engineers |accessdate=2007-11-27}}</ref>
* Lane changes&mdash; Allowed or not
* Diameter&mdash;The greater the traffic, the larger the circle.<ref name="ModernRoundabouts"/>
* Island function&mdash;Parking, parks, fountains, etc.<ref name="ModernRoundabouts"/>

[[Image:paris.etoile.arp.750pix.jpg|thumb|300px|Traffic 10-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.]]

==History==
French architect [[Eugène Hénard]] was designing one-way circular intersections as early as 1877.<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 & Phil Jones, ''Improving traffic behaviour and safety through urban design'', Proceedings of ICE – Civil Engineering, volume 158 Issue 5 May 2005 p. 41 http://www.hamilton-baillie.co.uk/papers/ICE_paper_April05.pdf</ref> American architect [[William Phelps Eno]] favored small traffic circles. He designed New York City's famous [[Columbus Circle]], which was built in 1905. Other circular intersections were subsequently built in the United States, though many were large diameter 'rotaries' that enabled high speed merge and weave maneuvers. These designs were doomed to failure for two primary reasons:
*It takes a large diameter circle to provide enough room for merging at speed. Although some of these circles were huge (many were in excess of 100 meters or 300 feet in diameter), they were not large enough for high-speed merging.{{Citation needed|date=March 2011}}
*Giving priority to entering traffic means that more vehicles can enter the circulatory roadway than it can handle. The result is congestion within the circle which could not clear without police intervention.

The experience with traffic circles and rotaries in the US was almost entirely negative,{{Citation needed|date=March 2011}} characterized by high accident rates and congestion problems. By the mid 1950s, construction of traffic circles and rotaries had ceased entirely. The experience with traffic circles in other countries was not much better until the development of the modern [[roundabout]] in the United Kingdom during the 1960s.

==Examples of traffic circles==
[[Image:Rotor Zagreb-crop.jpg|thumb|250px|The [[Western Rotary]] in [[Zagreb]], [[Croatia]] with tram lines passing underneath.]]

===United States===

====Rotaries in parts of New England====
{{main|Rotaries in Massachusetts}}
Traffic circles are referred to as "rotaries" in Massachusetts as well as parts of Connecticut, New Hampshire & Vermont.

====Traffic circles in other parts of the US====
<!-- From Geekdiva, Feb. 2016: Please, someone with the energy to do so, finish standardizing the format and punctuation in this section and throughout the article. Format template: (not all parts need to be used for each location; note the period at the end since if some lines would be awkward without a closing period, all need to end in one):
*[[Location]]: comment on location's circles, including [[Circle 1]] ({{Coord}}), Circle 2; for more see [[List of...]]. -->
*[[Washington, D.C.]]: numerous traffic circles; see [[List of circles in Washington, D.C.]]
*[[New Jersey]]: multiple current and former traffic circles; see [[List of traffic circles in New Jersey]].
*[[Berkeley, California]]: traffic circles (usually paired with stop signs) throughout the city; Marin Fountain Circle, one of few named circles, is the intersection of six streets (<small>{{Coord|37.890202|N|122.272428|W|name=Berkeley, CA|format=dec}}</small>).
*[[Indianapolis|Indianapolis, Indiana]]: Monument Circle, surrounding the [[Soldiers' and Sailors' Monument (Indianapolis)|Soldiers' and Sailors' Monument]] in the downtown area.
*[[New Orleans|New Orleans, Louisiana]]: [[Lee Circle]].
*[[Columbus Circle]], [[Frederick Douglass Circle]], and [[Duke Ellington Circle]] in [[Manhattan]], [[New York City]]
*Park Circle, [[Grand Army Plaza]], and Bartel-Pritchard Square in [[Brooklyn]], New York City
*[[Maryland]] has numerous traffic circles, especially at state highway junctions. Notable ones include: State Circle and Church Circle in [[Annapolis, Maryland|Annapolis]], [[Washington Monument (Baltimore)|Washington Monument Circle]] on Charles Street in [[Baltimore]], and Millenium Park Circle in [[Towson, Maryland|Towson]].
*MacArthur Drive Traffic Circle in [[Alexandria, Louisiana]]
*[[U.S. Highway 1|U.S. Bypass Highway 1]] at [[U.S. Highway 4]]/[[New Hampshire Route 16]], and [[interstate 95]] in [[Portsmouth, New Hampshire]] (Referred to locally as the [[Portsmouth Traffic Circle]])
*Weatherford Circle, [[U.S. Highway 377]] at [[Texas State Highway 183]] in [[Benbrook, Texas]] (Referred to locally as a [[Traffic Circle]])
*[[Shirlington Circle]] ([[Interstate 395 (District of Columbia–Virginia)|Interstate 395]] & [[Virginia State Route 402]]), [[Shirlington, Arlington, Virginia|Shirlington, Virginia]], has off ramps inside the rotary and multiple at-grade streets. <small>{{Coord|38|50|26|N|77|5|6|W|name=Shirlington, Virginia|format=dec}}</small>
*Union Square (aka "the Oval"), [[Milford, New Hampshire]]
*[[Benjamin Franklin Parkway]] in [[Philadelphia]]
*Mecom Fountain Circle, in the [[Houston Museum District]], intersection of Main Street, Montrose Boulevard, and Herman Park Drive, in [[Houston, Texas]].
*[[New Braunfels, Texas]]: Intersection of Seguin Avenue/Texas SH 46 Business and San Antonio Avenue downtown at Main Plaza.
*[[Los Alamitos Circle]] in [[Long Beach, California]]
*Centre Square in [[Easton, Pennsylvania]], where access is controlled by traffic lights.
*[[U.S. Highway 1]] and Maine Highway 236 in [[Kittery, Maine]]
*[[U.S. Highway 302]] and [[U.S. Highway 202]] in [[Windham, Maine]]
*[[U.S. Highway 202]], [[U.S. Highway 201]], and Maine state highway 17 in [[Augusta, Maine]], called Cony Circle
*[[U.S. Highway 202]], Maine state highway 104 and Maine state highway 27 in [[Augusta, Maine]], called Memorial Circle
* At the eastern end of [[Parkways of Louisville, Kentucky#Eastern Parkway|Eastern Parkway]] in [[Louisville, Kentucky]], intersecting with Cherokee Road at an entrance to [[Cherokee Park]]. All accesses are controlled with stop signs.
*R A Long Square in [[Longview, Washington]], where Washington and Olympia Ways meet. <small>{{Coord|46.139306|N|122.938818|W|name=Longview, Washington|format=dec}}
*[[Illinois Route 58]] known as Golf Road, in [[Des Plaines, Illinois]]. Two streets leading to [[U.S. Highway 14]] (Northwest Highway).
*A small, apparently unnamed traffic circle at the intersection of Rancho California Road and Anza Road, just east of [[Temecula, California]]. <small>{{Coord|33.534079|N|117.055919|W}}</small>
*North end of [[Palisades Interstate Parkway]] in [[Fort Montgomery, New York]], at junction with US 9W and US 202.
*The intersection of 41st Street and Avenue B in [[Austin, Texas]]. <small>{{Coord|30.305483|N|97.733975|W}}</small>

===Elsewhere===
*[[Remedios Circle]], [[Malate, Manila|Malate]], [[Manila]]
*[[Philippines–Thailand Friendship Circle]], [[Santa Ana, Manila|Santa Ana]], [[Manila]]
*[[Place Charles de Gaulle]] ([[Arc de Triomphe]]), [[Paris]]
*[[Marquis of Pombal Square|Praça do Marquês de Pombal]], [[Lisbon]], which comprises two concentric traffic-light controlled circles for motor vehicles, separated by a green space with foot and cycle paths

==See also==
{{commons category|Traffic circles}}
{{columns-list|2|
*[[Direction of traffic]]
*[[History of road transport]]
*[[History of urban planning]]
*[[History of street lighting in the United States]]
*[[History of roads in Ireland]]
*[[Public works]]
*[[Roundabout]]
*[[Traffic collision]]
*[[Traffic congestion]]
*[[Travel]]
*[[Urban planner]]
*[[Urban planning]]
}}
}}

==References==
{{reflist|2}}

{{Road junction types}}
{{Use dmy dates|date=March 2011}}

[[Category:Roundabouts and traffic circles| ]]
[[Category:Road junction types]]

Latest revision as of 21:02, 7 March 2023

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