Design
Design criteria include:
- Right-of-way—whether entering or circling vehicles have the right of way. The New Jersey Driver's Manual recommends that, in the absence of flow control signs, traffic yields based on "historically established traffic flow patterns", and there are no set rules. In New England, Washington, D.C. and New York State, entering traffic yields, as is the norm in virtually all countries outside of the U.S.
- Angle of entry— Angles range from glancing (tangential) that allow full-speed entry to 90 degree angles (perpendicular).
- Traffic speed—High entry speeds (over 30 mph / 50 km/h) require circulating vehicles to yield, often stopping, which lowers capacity and increases crash rates than modern roundabouts.
- Lane changes— Allowed or not
- Diameter—The greater the traffic, the larger the circle.
- Island function—Parking, parks, fountains, etc.
Read more about this topic: Traffic Circle
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