Imagine a world without stoplights; IIHS says roundabouts may be safer than intersections

Roundabouts, traffic circles, rotaries, whatever they’re called, the IIHS has delivered good news: they may create safer roads for drivers.

A new study from the insurance industry-funded safety group found roundabouts not only helped reduce crashes in areas that would typically employ a traditional intersection but also they nearly eliminate the most severe kinds of crashes. These are right-angle, left-turn, and head-on collisions. Since drivers need to yield and slow significantly to maneuver through a roundabout, they are inherently safer and less prone to extreme crashes.

The study looked at Washington state, specifically, which has more than 300 roundabouts. The traffic circles were constructed between 2009-2015 and the safety group looked at crash data for the first full year after an area completed a new roundabout. Traffic volumes, unemployment, and miles driven were all factored in to produce meaningful results. Finally, the IIHS separated findings between two types of roundabouts: single-lane and two-lane. For this study, the IIHS looked at 98 single-lane and 29 two-lane roundabouts.


Each year, crashes at two-lane roundabouts dropped by 9 percent. At single-lane roundabouts, they decreased 7 percent per year. The results likely factor in that drivers become more used to roundabouts and how they flow with time. The IIHS said it’s not uncommon for crashes to initially spike. A 2012 study found crashes increased at two-lane roundabouts after they replaced traditional intersections. Overall, the Washington State Department of Transportation, which worked with the IIHS, found an overall 37 percent decrease in crashes.

The types of crashes that fell the most may be the most important takeaway. Fatal crashes dropped 90 percent, while crashes where a driver or passenger was injured sunk 75 percent. Pedestrian collisions also dropped 40 percent.

The IIHS offered advice to help drivers better understand how roundabouts work, rather than let motorists hash things out on their own. The safety group called for clearer markings, appropriate curves, and even landscaping to reduce a driver’s desire to speed through the curve.

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