Most of the streets that are being looked at for traffic calming treatments are not running at capacity. Treatments made to these streets increase capacity but reduce speed. Traffic circles are very different from roundabouts. Traffic circles are approximately 300 ft. in diameter. Drivers can drive 30 to 40 mph around them.
People are scared of the speed and the merging that occur in traffic circles.
Roundabouts are usually designed as small as possible. The smallest roundabout built by Mr. Wallwork was 5 feet in diameter, and the biggest was about 120 feet in diameter. With roundabouts, one can see every entry and exit point. One cannot get lost in a roundabout. Most people usually drive through a roundabout at speeds between 10 and 20 mph.