Roundabouts and Traffic Circles

Car Care All About Roundabouts - and why they are not traffic circles roundabout is a circular intersection that moves traffic counterclockwise around a central island. CIRCULATORY ROADWAY The roundabout's design promotes safety by lowering driving speeds and reducing the number of conflict points. There are only eight conflict points in a roundabout, compared with 32 in a typical four-way intersection. COUNTERCLOCKWISE CIRCULATION SIDEWALK Having fewer conflict points lessens the likelihood of an accident. A roundabout also allows pedestrians to cross streets more safely by crossing one lane at a time. CENTRAL ISLAND This type of intersection requires no traffic signals because left turns across traffic are eliminated. SPLITTER ISLAND YIELD LINE Differences Between Modern Roundabouts APRON and Traffic Circles, or Rotaries ACCESSIBLE PEDESTRIAN CROSSING (aids larger vehicles) Source: Wisconsin Department of Transportation Feature Modern Roundabout Traffic Circle, or Rotary Control at Entry Yield at entry Roundabout Stop sign, traffic signal or giving priority to entering vehicle. Operational Characteristics Vehicles are sorted by destination at the approach. Weaving within the circulatory provided to accommodate roadway is minimized. Weaving is unavoidable, and weaving sections are conflicting movements. WEAVING PERMITTED TRAFFIC SIGNAL OR STOP SIGN Large entry angle helps to create entry deflection to control speed through the roundabout. Deflection Entry angle can be more extreme, ranging from nea right angle to reduced angle allowing higher entry speed. Maintain relatively low speeds (< 25 mph) Higher speeds allowed (> 25 mph) Speed LARGE DIAMETER Larger diameters allowed. Small-diameter circle sometimes used for traffic calming. Circle Diameter Smaller diameters improve safety. No pedestrian activity on central island. Some large traffic circles allow pedestrian crossing to and from the central island. Pedestrian Crossing Splitter Island Required Optional EXTREME ANGLE OF ENTRY On large traffic circles, occasionally parking is permitted within circulating roadway. Parking No parking on the circulatory roadway or in close proximity of the yield line. Traffic Circle (Rotary) Source: North Carolina Department of Transportation creators.com / Frank Mariani