(WTOL/WOIO) - Roundabouts or traffic circles. No matter what you call them, most people have an opinion about them, as they've been popping up more and more around the city and in the country over the last few years.
But do roundabout intersections work? ODOT Traffic Engineer Scott Ockunzzi recently answered some questions about them.
Q: Do roundabouts work?
A: Roundabouts can significantly increase safety and improve operations (reduce delay) at intersections. For safety reasons, roundabouts are effective because they reduce the number of potential conflict points in an intersection, meaning they reduce or eliminate the chance of an angle or left turn crash from occurring. Operationally, roundabouts are easy to navigate if you remember the rule that vehicles inside the roundabout have the right of way, and vehicles entering the roundabout must yield on entry.
The graphic below shows all the potential points of conflict (white dots, crossing traffic) with the potential for accidents in a normal intersection as compared to a roundabout.
Q: Does a roundabout reduce crashes?
A: Some recent data from Federal Highway Administration (FHWA) shows that if a signalized intersection is converted to a roundabout, total crashes are reduced by 48%, with a 78% reduction of fatal and injury crashes in a rural area and 48% reduction of fatal and injury crashes in an urban area. If a two-way (minor road) stop-controlled intersection is converted to a roundabout, there is a 44% reduction in total crashes, with an 87% reduction in fatal and injury crashes in a rural area and, in an urban area 78% reduction in fatal and injury crashes for a single lane roundabout and a 72% reduction in fatal and injury crashes for a two lane roundabout.
Q: When and where are roundabouts used?
A: Roundabouts are especially effective at high crash rate locations, intersections with large delays, intersections with complex geometry (more than four approaches), and locations with high left turn volumes, but they can be effective at most any intersection if designed and implemented properly.
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