A modern roundabout is an unsignalized circular intersection engineered to maximize safety and minimize traffic delay. Over the last few decades, thousands of roundabouts have been installed in Europe, Australia and other parts of the world. Recently, they have gained support in the United States with states such as Maryland, Colorado, Florida, Washington, and more recently, New York, getting experience with their use and design. Drivers in those states also are becoming comfortable with their use. In the cities and towns where roundabouts have been built, and even where the public has been hesitant about accepting them initially, roundabouts ultimately have been accepted enthusiastically because of the increased safety they provide, along with traffic calming, and aesthetic benefits.
Research shows roundabouts reduce crashes, clear up congestion and can save cities money. But America has a fraction of the roundabouts that far smaller countries like France, Spain and the United Kingdom have. Some states are adopting them, and the small town of Carmel, Indiana, now leads European cities. The mayor credits them with helping revitalize his city. So why haven't more U.S. cities done this? Why do some people resist them? Are they are all they are cracked up to be?
A Citizen’s Guide To Roundabouts (PDF)