Installing roundabouts can make roads safer, lead to a reduction in traffic accidents

Ever notice how many popular trends got their start in Europe before making their way to the U.S.? Think music like The Beatles and punk rock (United Kingdom), fashion (Paris), compact cars (Germany and the Volkswagen Beetle). They all got their start in Europe.

Unfortunately, one of the roadway standards embraced throughout Europe but still being largely absent in the U.S—despite an enviable track record for safety, reduced congestion and environmental benefits—is the roundabout. According to Statista, France holds the title for most roundabouts in the world, with approximately 50,000 or 967 for every million residents. Spain is second with 591 roundabouts per million residents or some 30,000, followed by the U.K. with 25,000 or 489 per million.

The U.S., by comparison, currently has only about 10,000 roundabouts, despite adding 500-700 per year since 2008. Some states—notably New York and Virginia—now have roundabout-first policies in place, while cities such as Carmel, Ind., have converted one in every 17 road junctions into a roundabout. Still, the U.S. lags significantly behind its European counterparts due in large part, according to the U.S. Department of Transportation, to historical factors, roundabouts’ overcomplicated designs and the dominance of traffic signals.

Prompted by repeated studies that support the safety advantages of roundabouts, though, the U.S. seems to be more open to adopting roundabouts than ever before. While challenges such as high traffic capacities and bike and pedestrian safety persist, research conducted by the Insurance Institute for Highway Safety (IIHS) indicates that roundabouts are responsible for a 62-67 percent reduction in total traffic accidents and an 85-87 percent reduction in injury cases.

In marked contrast, 24 percent of all U.S. crash deaths in 2021—10,445 people—occurred at traditional intersections. That same year, an estimated 127,000 people were injured in accidents that occurred from running red lights. Those horrendous numbers, coupled with the fact that speeding is responsible for one-third of all motor vehicle fatalities in the U.S., has more jurisdictions nationwide considering roundabouts as a feasible replacement for traditional intersections.

The case for roundabouts
Like them or hate them, one of the things roundabouts do is reduce travel speed. That lower speed combined with the angle of collision caused by the roundabout design ultimately results in less severe traffic accidents and less damage to vehicles, their occupants, and nearby pedestrians and bicyclists.

Unfortunately, local departments of transportation often find themselves confronted with complaints about excessive traffic congestion and demands to allocate limited road improvement budgets to modifications that will increase speeds, enabling vehicles to move more rapidly from Point A to Point B. To counter such arguments, agencies should consider seven key points that make the case for roundabouts and why they represent a safer alternative to signalized intersections.

Roundabouts are not without their downside
All of that is not to say roundabouts are a perfect solution or that they should be used at every intersection. Single-lane roundabouts, for example, have a difficult time accommodating a throughput of more than 25,000 vehicles per day.

While an obvious solution to that issue may be multilane roundabouts, that design presents several problems. According to the Federal Highway Administration (FHWA), because such roundabouts have a significant gap between entry and exit points, vehicles entering may find themselves driving parallel to those already circulating the roundabout. This can cause drivers on the outer lane to mistakenly think those on the inner lane must shift to the outer lane before exiting.

To counter such problems, the FHWA has advanced turbo roundabouts, which feature second lanes opposite entry points and barriers to prevent mid-roundabout lane changes, ensuring a smoother traffic flow and lessening driver confusion. Turbo roundabouts’ design also forces vehicles to slow down while strategically blocking the views of incoming vehicles and providing added space for larger vehicles—all of which makes drivers choose their planned exit lanes before even entering the roundabout.

Roundabouts have also been criticized for being dangerous to bicyclists. Researchers in Belgium, for example, found that single-lane roundabouts increased crashes with bicyclists by 93 percent. That number can be dramatically reduced, however, by providing a protected, bicycle-only lane. Danish researchers found that roundabouts with separated lanes experienced an 84 percent drop in crashes.

Safety depends on design
Bottom line, proper planning, design and education are crucial to ensure the safety benefits of roundabouts are fully realized. Clear signage in the right places in advance of the roundabout, the addition of bike lanes and pedestrian crosswalks, and the proper geometry of entry and exit lanes and sight distances can all be employed to slow drivers down and improve safety. It is up to today’s urban planners to determine how best to utilize such features so that roundabouts can be integrated into current roadway designs, slowing traffic, reducing collisions and keeping everyone safe.

Paul Dorr is director of engineering design at The Traffic Group, a Service-Disabled Veteran-Owned Small Business (SDVOSB), Maryland-based traffic engineering and transportation planning firm. For more information, visit www.trafficgroup.com or follow them on LinkedIn.