Design the center island so that, in conjunction with well-designed approach and departure lanes, it can control vehicle speeds through deflection. Maximize opportunities to landscape the intersection.
Rather than a large multi-lane roundabout, construct a smaller, multi-lane roundabout with metering signals that is adequate during the non-commute hours of the day. Use the metering signal for the short peak period when congestion can occur.
Use multi-lane/two-lane roundabouts sparingly, and only when single-lane roundabouts prove to be inadequate for the traffic volume, such as at freeway interchanges.
Size roundabouts with central diameters from 12 feet to 90 feet to fit a wide range of intersections and accommodate through movements and different turn movements by various design vehicles.
In urban areas and at locations with many crossing pedestrians, time the pedestrian phase to be on automatic recall, so pedestrians do not have to seek and push a pushbutton. Where push buttons are necessary, locate them at convenient locations.
