Tool Box
Neighborhood Traffic Management Program

ROUNDABOUT (SINGLE-LANE)

Like traffic circles, roundabouts require traffic to circulate counterclockwise around a center island. But unlike circles, roundabouts are used on higher volume streets to allocate right-of-way among competing movements. They are found primarily on collector streets, often substituting for traffic signals. They are larger than neighborhood traffic circles, have raised splitter islands to channel approaching traffic to the right, and do not have stop signs. Due to large amount of required right-of-way and construction costs, roundabouts may be most appropriate for new developments.

Roundabouts have an insignificant affect in reducing traffic speeds, but serve to allocate right-of-way at an intersection similar to a traffic signal. On average roundabouts can reduce the average number of accidents up to 33% when compared to a signalized intersection.

Advantages

• Enhanced safety compared to a traffic signal or stop sign
• Minimizes queuing at approaches to the intersection
• Less expensive to operate than traffic signals
• Can have positive aesthetic value
• Shorter pedestrian crossing distance

Disadvantages

• May require major reconstruction of an existing intersection
• Loss of on-street parking
• Continuous flow of traffic limits opportunity for pedestrians to cross (compared to signal)

For additional information please contact:

Tracy Whitley
Project Engineer
Sacramento County Department of Transportation
whitleyt@SacCounty.net