All About Roundabouts

Three features separate the modern roundabout from other forms of circular intersections.

(i) Diameter less than 100m, or 330′. A modern roundabout has a typical ICD (Inscribed Circle Diameter) of 90-150′ for a single lane, or 160-240′ for a two lane.

(ii) Yield on entry – vehicles within the roundabout always have the right-of-way. Older traffic circles often forced traffic within the circle to yield to entering vehicles.

(iii) Entry path deflection. Vehicles entering a roundabout must be guided by curbs or other channelization along a path which slows their speed before entering the circle.

Frequently Asked Questions

Will a roundabout work at a location with heavy pedestrian traffic?

Yes, in fact many roundabouts have been installed adjacent to schools and universities.

Will a roundabout work at a location with a railroad crossing?

Several are in operation near light and heavy rail alike.