Why no American roundabouts?
Traffic circles, or roundabouts, are known for their safety benefits, especially when compared to traditional traffic lights. Studies from both Europe and the U.S. show that roundabouts significantly reduce crash rates, particularly those involving fatalities or serious injuries. For example, intersections in Europe that were converted to roundabouts saw reductions in injury crashes by as much as 87% and overall crashes by up to 61%. In the U.S., implementing roundabouts in just 10% of signalized intersections could have prevented over 47,000 crashes in 2022, including nearly 300 fatalities.
One reason roundabouts are safer is their design, which forces drivers to slow down and eliminates the risk of high-speed, right-angle collisions common at intersections with traffic signals. They also simplify decision-making by having vehicles move in one direction, reducing the likelihood of accidents at multiple conflict points. In addition to fewer crashes, roundabouts are associated with improved pedestrian safety, as walkers only need to cross one direction of traffic at a time and benefit from shorter crossing distances.
Another key benefit is that roundabouts remain functional during power outages. Traffic signals depend on electricity, and an outage can lead to confusion and potential crashes at busy intersections. By contrast, roundabouts rely on simple right-of-way rules, keeping traffic moving smoothly even without power.
Despite these advantages, the U.S. has been slow to adopt roundabouts, with only 7,900 across the country compared to much higher numbers in Europe. However, as states like Indiana show, the trend is changing. Indiana, for example, saw a 90% reduction in fatalities and 76% fewer injuries after installing over 250 roundabouts since 2016.
World Economic Forum, IIHS, Kittelson & Associates, Federal Highway Administration.
