How do roundabouts affect safety?
Several features of roundabouts promote safety. At traditional intersections with stop signs or traffic signals, some of the most common types of crashes are right-angle, left-turn, and head-on collisions. These types of collisions can be severe because vehicles may be traveling through the intersection at high speeds. With roundabouts, these types of potentially serious crashes essentially are eliminated because vehicles travel in the same direction. Installing roundabouts in place of traffic signals can also reduce the likelihood of rear-end crashes and their severity by removing the incentive for drivers to speed up as they approach green lights and by reducing abrupt stops at red lights. The vehicle-to-vehicle conflicts that occur at roundabouts generally involve a vehicle merging into the circular roadway, with both vehicles traveling at low speeds — generally less than 20 mph in urban areas and less than 30-35 mph in rural areas.

A 2001 Institute study of 23 intersections in the United States reported that converting intersections from traffic signals or stop signs to roundabouts reduced injury crashes by 80 percent and all crashes by 40 percent.1 Similar results were reported by Eisenman et al.: a 75 percent decrease in injury crashes and a 37 percent decrease in total crashes at 35 intersections that were converted from traffic signals to roundabouts.2 Studies of intersections in Europe and Australia that were converted to roundabouts have reported 41-61 percent reductions in injury crashes and 45-75 percent reductions in severe injury crashes.3

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1. What is a roundabout?
2. How do roundabouts differ from older traffic circles and rotaries?
3. How do roundabouts affect safety?
4. What are the features of a good roundabout designs?
5. What are the common types of crashes at roundabouts? What can be done to prevent them?
6. How do roundabouts affect traffic flow?
7. Are there other benefits?
8. Can roundabouts accommodate larger vehicles?
9. How do roundabouts affect older drivers?
10. Are roundabouts safe for pedestrians?
11. Do drivers favor roundabouts?
12. What are the impediments to building roundabouts?
13. How common are roundabouts in the United States?
14. Do roundabouts require more space than traditional intersections?
15. What are appropriate locations for roundabouts?
16. What types of intersections may not be good candidates for roundabouts?