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Traffic Calming Devices →
Horizontal Speed Control Devices |
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| Traffic Circles |
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What are Traffic Circles?
- Raised islands usually placed in the center of intersections.
- Typically circular in shape and can be landscaped, painted, or left
unfinished as long as they are easily noticed.
- Designed so that all traffic must yield to traffic within the circle.
A YIELD sign usually controls traffic on all approaches.
- Effective by impeding the straight-through movement of an intersection
causing drivers to slow their vehicles as they proceed counter-clockwise
around.
- Ideal for residential applications.
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How are Traffic Circles designed?
- The design can vary significantly depending on the design purpose.
- The circles can be designed to be partially or fully mountable by
larger vehicles. This means that larger vehicles can ride over the whole
circle or part of the circle while making a tight turn or negotiating the
intersection.
- It is suggested that on-street parking be prohibited 10 meters from
the intersection.
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Where are Traffic Circles placed and how much are they?
- Traffic circles are typically used at non-signalized intersections
with average daily traffic volumes of less than 3,500 vehicles.
- Used primarily in residential neighbourhoods.
- Installation costs of simple traffic circles that requires no
modification to the existing curbs, gutters, and drains usually are
between $4,000 and $8,000.
- If the installation is more complex and requires modification to the
right-of-way and other road features, the cost could exceed $20,000.
- Landscaping the neighborhood traffic circle adds to the ongoing
maintenance costs.
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Advantages
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Disadvantages
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- Effective in reducing vehicle speed.
- Can significantly reduce serious motor vehicle collisions by
reducing right-angle conflicts.
- "The Insurance Corporation of British Columbia, summarizing 43
international studies, reported that circles reduce collisions by 82
percent."
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- May make left turn maneuvers difficult for emergency vehicles
and larger trucks.
- The potential exists for an increase in vehicle/bicycle
accidents and vehicle/pedestrian accidents as vehicles may not yield
properly or be deflected by the circle into a bicycle's or
pedestrian's path.
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Traffic Circle Issues & Comments
- Proper signage and possibly lighting are necessary to ensure that
drivers understand how to properly navigate the traffic circle.
- The center island doesn't necessarily need to be a circle; it an be
designed to fit the intersection configuration.
- Traffic circles work well when installed in conjunction with other
devices such as:
chokers and
medians.
- When designing a neighborhood traffic circle, considerable attention
should be given to aesthetics.
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