Editing Roundabout (section)

== Safety ==
{{See also|Traffic calming}}
[[File:Roundabout intersection diagram.svg|thumb|A comparison of possible collision points on a roundabout versus a traditional intersection]]
[[File:2008 03 12 - UMD - Roundabout viewed from Art Soc Bldg 4.JPG|thumb|Small modern roundabout in the United States, where vehicles are driven on the right]]
[[File:DiamondRoundabout.jpg|thumb|Roundabout in the United States with separated side lanes. Vehicles entering the roundabout give way to vehicles in the roundabout.]]
[[File:CarlandCrossRoundaboutA30Cornwall.jpg|thumb|A typical [[trunk road#United Kingdom|trunk road]] roundabout in the UK at [[Carland Cross]] on the [[A30 road|A30]] in [[Cornwall]], United Kingdom. There is a free-flow lane for the A30 towards [[Bodmin]] (nearest the camera).]]

Statistically, modern roundabouts are safer for drivers and pedestrians than both older-style traffic circles and traditional intersections.<ref>{{cite journal |title=A Comparative Evaluation of the Safety Performance of Roundabouts and Traditional Intersection Controls |first1=Shashi S. |last1=Nambisan |first2=Venu |last2=Parimi |date=March 2007 |journal=Institute of Transportation Engineers }}</ref> Compared with these other forms of intersections, modern roundabouts experience 39% fewer vehicle collisions, 76% fewer injuries and 90% fewer serious injuries and fatalities (according to a study of a sampling of roundabouts in the United States, when compared with the junctions they replaced).<ref>{{Cite web |url=https://www.k-state.edu/roundabouts/news/sr3505.pdf |title=Status Report |access-date=9 June 2014 |archive-url=https://web.archive.org/web/20140714142530/https://www.k-state.edu/roundabouts/news/sr3505.pdf |archive-date=14 July 2014 |url-status=dead }}</ref> At junctions with stop signs or traffic lights, the most serious accidents are right-angle, left-turn or head-on collisions where vehicles move fast and collide at high impact angles, e.g. head-on. Roundabouts virtually eliminate those types of crashes. Instead, most crashes are glancing blows at low angles of impact.<ref name="Richtmeyer">{{cite news | first=Richard | last=Richtmeyer | title=Safer Roundabouts Sprouting Up All Over New York, Nation | publisher=Associated Press | url=https://www.boston.com/news/local/connecticut/articles/2008/01/06/safer_roundabouts_sprouting_up_all_over_new_york_nation/ | archive-url=https://archive.today/20121215020745/http://www.boston.com/news/local/connecticut/articles/2008/01/06/safer_roundabouts_sprouting_up_all_over_new_york_nation/ | url-status=dead | archive-date=15 December 2012 | date=6 January 2008 | access-date=10 January 2008 }}</ref><ref>{{cite web|url=http://www.iihs.org/iihs/topics/t/roundabouts/topicoverview|title=Roundabouts - Topic overview|publisher=Insurance Institute for Highway Safety}}</ref> Further, a study based on satellite imagery of all intersections in Australia observed consistently low speeds on roundabouts compared to other intersection types, contributing to reduced injury severity in case of a crash.<ref>{{cite journal |last1=Wijnands |first1=J.S. |last2=Zhao |first2=H. |last3=Nice |first3=K.A. |last4=Thompson |first4=J. |last5=Scully |first5=K. |last6=Guo |first6=J. |last7=Stevenson |first7=M. |title=Identifying safe intersection design through unsupervised feature extraction from satellite imagery |journal=Computer-Aided Civil and Infrastructure Engineering |year=2020 |volume=36 |issue=3 |pages=346–361 |doi=10.1111/mice.12623|arxiv=2010.15343 |s2cid=225103031 }} [https://onlinelibrary.wiley.com/doi/epdf/10.1111/mice.12623 PDF]</ref>

Some larger roundabouts take foot and bicycle traffic through [[underpass]]es or alternate routes. However, an analysis<ref>Wilke, A. and Koorey, G. (2001). ''How Safe are Roundabouts for Cyclists?'' In TranSafe Issue 5, April 2001. Wellington, NZ. [http://viastrada.co.nz/sites/viastrada/files/Transafe_05.pdf PDF] {{webarchive|url=https://web.archive.org/web/20081015101010/http://viastrada.co.nz/sites/viastrada/files/Transafe_05.pdf |date=15 October 2008 }}</ref> of the New Zealand national crash database<ref>{{cite web|url=http://www.landtransport.govt.nz/research/cas/|title=Crash analysis system|access-date=29 November 2007}}</ref> for the period 1996–2000 shows that 26% of cyclists reported injury crashes happened at roundabouts, compared to 6% at traffic signals and 13% at priority controlled junctions. The New Zealand researchers propose that low vehicle speeds, circulatory lane markings and mountable centre aprons for trucks can reduce the problem.<ref>Campbell, D., Jurisich, I., Dunn, R. 2006. ''Improved multi-lane roundabout designs for cyclists.'' Land Transport New Zealand Research Report 287. 140 pp. [http://www.landtransport.govt.nz/research/reports/287.pdf PDF]</ref> The most common roundabout crash type for cyclists, according to the New Zealand study, involves a motor vehicle entering the roundabout and colliding with a cyclist who already is travelling around the roundabout (more than half of cyclist/roundabout crashes in New Zealand fall into this category). The next most common crash type involves motorists leaving the roundabout colliding with cyclists who are continuing farther around the perimeter.

=== Vision-impaired pedestrians ===
Poorly designed walkways increase risks for the vision-impaired, because it is more difficult than at a signalised intersection to audibly detect whether there is a sufficient gap in traffic to cross safely. At a signalised intersection, traffic comes to a stop, and an audible sound can be generated to indicate that it is time to cross.<ref>Pedestrian Access to Modern Roundabouts: Design and Operational Issues for Pedestrians who are Blind [http://www.access-board.gov/research/roundabouts/bulletin.htm, retrieved 6/26/2010 access-board.gov] {{webarchive |url=https://web.archive.org/web/20120331234233/http://www.access-board.gov/research/roundabouts/bulletin.htm |date=31 March 2012 }}</ref>

This issue has led to a conflict in the United States between the vision-impaired and [[civil engineering]] communities. One solution is to provide manually-operated pedestrian crossing signals at each entry. This increases construction and operation costs, and requires some way to disrupt traffic long enough for the pedestrian to cross (such as a [[HAWK beacon]]) that defeats the purpose of the roundabout. Signalisation also increases delays for most pedestrians during periods of light traffic, since pedestrians need to wait for a signal to change before (legally) crossing.<ref>Bill Baranowski, P.E., [http://www.teachamerica.com/roundabouts/RA057A_ppr_Baranowski.pdf Pedestrian Crosswalk Signals at Roundabouts: Where are they Applicable?]</ref>

Signalised pedestrian crossings are normally used on large-diameter roundabout interchanges rather than small-diameter modern roundabouts.