Editing Roundabout (section)

=== 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"/>