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Roundabouts Explained

Confusing for the uninitiated, roundabouts are actually the safest and most efficient form of traffic intersection.

A Better Way Round

Aerial view of a roundabout
Aerial view of a roundabout

For many American drivers, approaching a roundabout can be the cause of anxiety, fear, and even anger. People complain at local planning meetings when one of them is proposed: They’re confusing! They’re dangerous! They’re useless! But, while most of us are used to four-way intersections controlled by traffic lights, the roundabout is actually the safer and more efficient intersection by a wide margin. Here’s how to navigate a roundabout and why your city needs more of them.

No, It’s Not a Traffic Circle

Arc De Triomphe in Paris
Arc De Triomphe in Paris

People often conflate the problematic traffic circle with the innovative roundabout. You may recall Chevy Chase getting stuck in the traffic circle around the Arc De Triomphe in Paris or Homer Simpson getting caught in one in London. Other famous traffic circles include Columbus Circle in New York City and the Angle of Independence in Mexico City. Unfortunately, these confusing traffic circles have given us Americans the wrong impression of roundabouts.

So, here’s what a roundabout is and is not. It is a three- or four-way intersection where traffic moves around a central island using the “give-way” or yield principle to control the flow of traffic. Developed by Englishman Frank Blackmore, the roundabout is a reimagining of the classic traffic circle. A traffic circle, in contrast, controls the flow of traffic using traffic lights and requires drivers in the circle to yield to traffic entering the circle.

Columbus Circle in New York City
Columbus Circle in New York City

Used in the early days of the automobile, the traffic circle fell out of favor with civil engineers as it proved to be confusing for motorists, caused more congestion rather than less, and increased accident rates. Blackmore’s solution was to eliminate signaling and reverse the “give-way” or yield so that incoming traffic yielded to vehicles already in the roundabout. The result was a vastly safer and more efficient intersection.

How to Use a Roundabout

Roundabout yield sign
Roundabout yield sign

Though much more common in the rest of the world, roundabouts are seeing greater adoption throughout the US. That they are still on the rare side means many motorists never learned much, if anything, about them in traffic school. Therefore, encountering one for the first time can be a bit nerve wracking for drivers. But, as you’ll see, they are actually intuitive and simple to navigate.

The first thing you should do when approaching a roundabout is slow down. Remember, it operates based on yielding to traffic, not simply merging with traffic. Here’s how to navigate a roundabout:

  • As you approach you should notice signage and road markings that indicate which lane you need to be in for your desired direction.
  • Nearing the roundabout, watch for pedestrians and cyclists.
  • Then, once you’ve reached the yield point, watch for a gap in traffic before safely entering.
Roundabout lanes
Roundabout lanes
  • Make sure to stay in your chosen lane and don’t stop once you’re in the roundabout.
  • If there is an emergency vehicle also in the roundabout it is recommended that you exit before pulling safely to the side of the road.
  • Remember to avoid larger vehicles while in the roundabout. Their wider turning radius means trucks and buses often need to take up more than a single lane. (In fact, you’ll notice a large skirt/apron of concrete around the central island of a roundabout designed to accommodate the rear wheels of large vehicles.)
  • To exit, simply take a right turn out of the roundabout and toward your desired direction.

The Argument for Roundabouts

Roundabout with traffic
Roundabout with traffic

The simple fact is, your city, my city, they need more roundabouts. Here’s why. First, as noted above, they are safer. One study by the IIHS (Insurance Institute for Highway Safety) found that roundabouts reduced accident rates by 35%, injurious accidents by 76%, and fatal crashes by 89%. Consider too, that up to half of all traffic accidents in the US occur at intersections. The boon to traffic safety from roundabout adoption is clear.

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So why are they so much safer? First, they slow down traffic. Reduced speed leaves more time for drivers to react and reduces the force of impact in the case of a crash. Second, the roundabout’s circular nature creates gentle crossing angles. This means that when vehicles collide, they tend to side-swipe each other as opposed to the head-on or side-on collisions common at traditional intersections. A roundabout also separates the flow of traffic. In a roundabout, there’s no crossing other lanes, no confusing double left turn lanes and the like, instead just a simple, counter-clockwork flow of traffic.

Angel of Independence in Mexico City
Angel of Independence in Mexico City

Perhaps the greatest reason they are safer is because they force drivers to pay closer attention. Part of why intersections controlled by traffic lights can be dangerous is because we, as drivers, have farmed out our responsibility to pay attention, mentally if not legally, to the traffic light. Because it is based on yielding, roundabouts force drivers to pay close attention to pedestrians, cyclists, and other vehicles.

Safety isn’t even the sole benefit of roundabouts, either. They’re also cheaper to maintain and operate than intersections with lights. Though the intersections themselves are a little bit larger, roundabouts don’t require the mess of turning lane approaches of traditional intersections, meaning a smaller overall footprint. And lastly, roundabouts are prettier. The central island of most of them feature a touch of green space, often including sculptural art or floral display.

Hopefully we’ve been able to alleviate any of you nagging anxiety and convinced you that the roundabout isn’t just a great song by the band Yes.

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Chris Kaiser

Chris’ greatest passions include topiary, spelunking, and pushing aging compact cars well past 200,000 miles on cross-country road trips. His taste in cars runs from the classic and esoteric to the deeply practical with an abiding affection for VW Things, old Studebakers, and all things hybrid-crossover.

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