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TRAFFIC CIRCLES (ROUNDABOUTS)
Traffic circles are intersections with central circular islands and a circular one-way roadway around the island Drivers yield to vehicles already circulating within the intersection.
They are self-enforcing and can improve safety due to the replacement of vehicular crossing movements with merging movements. Design standards are strict and primarily originate from the UK and Australia. They can help beautification projects if the central island is planted.
Temporary Installation
Culver City, CA
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Permanent Installation
Alhambra, CA |
PROS
1. Speed reduction possible.
2. Self-enforcing.
3. Provides opportunity for roadway beautification.
4. Reduces accidents in many cases.
5. Creates less delays.
6. Can accommodate all vehicles if correctly designed.
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CONS
1. Difficult for cyclists to use.
2. Can be difficult for pedestrians.
3. Needs to be properly designed.
4. Needs to be well illuminated.
5. Uneven entry volumes can reduce effectiveness.
6. May cause initial confusion for drivers.
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Summary of Effectiveness
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Volume Reduction
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Possible
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Speed Reduction
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Yes
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Safety Improvement
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Yes (Cars)
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-
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-
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Streets to Use On Collector, Local
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Any
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Use on Bus Route
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Yes
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Use with Curbs and Gutters
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Yes
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Spot or Area-wide Use
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Spot
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-
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-
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Emergency Service Access Issues
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No
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Impacts on Arterials
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N/A
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Change in % Trucks
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Unknown
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Environmental Changes
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Unknown
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-
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-
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Dependence on Enforcement
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No
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Level of Violation
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N/A
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-
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-
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Aesthetics and Landscaping
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Landscaping
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