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Roundabouts


Roundabouts are currently gaining popularity in the United States as an effective way to manage traffic flow and improve safety at intersections.  There are at least 20 existing roundabouts in Southeast Michigan with more planned or proposed. 

What is a roundabout?
A roundabout is a type of circular intersection, but not all circular intersections are roundabouts. A modern roundabout differs from traffic circles, many of which were built in the first half of the 20th century in the United States.  Traffic circles are often wider allowing for high traffic speeds and give priority to entering vehicles.  Traffic circles fell out of favor in the 1950s because of their inability to handle high volumes of traffic and poor safety records.  In the 1960s a "modern roundabout" was developed in the United Kingdom to rectify the problems associated with the traffic circle. 

Features of a Modern Roundabout
A modern roundabout gives the right of way to circulating vehicles in the roundabout.  Cars wishing to enter the roundabout must yield to circulating traffic before entering the circle.  All traffic moves counter-clockwise, pedestrian access is only on the approach legs of the roundabout behind the yield line (i.e. not within the circulating traffic area) and there is no parking allowed anywhere in the roundabout. 

Typical Single Lane Roundabout Design

Modern Roundabout Diagram 

Safety
Roundabouts have been shown to reduce crashes at intersections

CrashReductions 
Source: Insurance Institute for Highway Safety 2001

With more roundabouts being installed in Michigan, drivers must also know how to navigate them during an emergency. The Emergency Vehicle Law requires that vehicles get out of a roundabout quickly when an emergency vehicle approaches. 

Icon of paper page with plus signAdditional materials on Roundabouts