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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
|
Yes
|
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Safety
Improvement
|
Yes
(Cars)
|
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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
|
Yes
|
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Spot
or Area-wide Use
|
Spot
|
|
-
|
-
|
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Emergency
Service Access Issues
|
No
|
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Impacts
on Arterials
|
N/A
|
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Change
in % Trucks
|
Unknown
|
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Environmental
Changes
|
Unknown
|
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-
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-
|
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Dependence
on Enforcement
|
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
|
Landscaping
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