Roundabout vs. intersection: Which is more efficient?


Fact Box

  • One-way circular intersections (also called roundabouts) were first thought to have been invented by French architect, Eugene Henard, in 1877. Around this era, American architect, William Eno, was developing a similar circular intersection in New York City.
  • France is the leading country in roundabouts per one million inhabitants at 967.
  • In 2021, it is estimated that there are about 8,800 roundabouts in the entirety of the United States. 
  • Carmel, Indiana has the most roundabouts of any US city, totaling 138.
  • The US Department of Transportation estimates each year that “roughly one–quarter of traffic fatalities and about one–half of all traffic injuries in the United States are attributed to intersections.” Federal data reports total traffic fatalities to total 38,824 in 2020, with 10,626 of those being intersection-related.

Curtice (Intersection)

The first roundabout built for the automotive age is believed to be in 1905 for New York City's Columbus Circle. Yet, roundabouts haven’t gained as popular of a foothold in the US as it has in Europe. While roundabouts are extremely common in many European cities and have been for several decades now, drivers in the US almost universally hate them, and for good reason.

American drivers are often confused by roundabouts—when or how to get off, sometimes getting caught in a perpetual loop. They require an understanding of when to enter and exit and when and how to allow other drivers to continue with the flow of traffic. Traffic in roundabouts is notably much slower, forcing traffic to reduce their speed significantly overall. They are, by design, slow. Further, roundabouts require much more public space to operate than a standard light-controlled intersection and can cost millions to construct in some states.

In instances where there are busy main roads, cars entering a roundabout from a minor road usually have to wait much longer for a safe and acceptable gap to enter than it would take if there were a traffic light. Conversely, intersections with traffic lights are simple and easy to understand—red means stop, green means go, with the yellow light serving as a warning the light is about to change from green to red. Americans even have a child’s game dedicated to traffic lights! 

When comparing roundabouts and intersections, concern for pedestrians or bicyclists can often be overlooked. For those, a standard intersection can be safer and more predictable than crossing a roundabout. Intersections are the more efficient and obvious design approach to vehicular travel across short and long distances and should remain in place everywhere.

Mark (Roundabout)

Roundabouts are inherently safer and more practical than intersections, as the US Department of Transportation reports that 'more than 50 percent of the combined total of fatal and injury crashes occur at or near intersections.' Roundabouts are safer, allowing drivers to yield to oncoming traffic, as opposed to intersections that require all parties to either fully stop for long waits or allow drivers to soar through the roads despite the intersection light shining yellow or red. Intersections are often approached at dangerously high speeds, catastrophic for cars and pedestrians entering at the wrong time and colliding with a vehicle moving at speeds over 35 mph. Roundabouts allow for traffic to maintain a consistent and manageable flow. Intersections often bring traffic to a complete halt, creating potential scenarios for various impediments.

Roundabouts are also more pedestrian-friendly. They allow shorter crossing times that are safer for both pedestrians and drivers. The entire concept of a roundabout is to allow vehicles a broader spectrum of visibility and control. Intersections are rife with what are known as 'conflict points”—accidents waiting to happen. However, roundabouts decrease the number of conflict points by about 75%, which is an astoundingly reassuring statistic.

Not only are roundabouts safer, but they are also better for the environment. By bringing traffic to a more navigable speed, roundabouts allow for fewer vehicle emissions and fuel consumption. This is especially pivotal in high-traffic areas, such as major cities. Intersections are dangerous in both design and execution. Roundabouts all but nullify the dreaded left turn that is responsible for a high volume of car accidents. Even the most seasoned drivers have to exercise extreme caution when approaching certain intersections. There is no debate; roundabouts are a safer and more efficient alternative to intersections.

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