Also, in my experience, roundabouts work best if traffic at all entrances/exits are roughly equal (within an order of magnitude or two) If traffic flow becomes

Also, in my experience, roundabouts work best if traffic at all entrances/exits are roughly equal (within an order of magnitude or two) If traffic flow becomes highly unbalanced, a constant flow of cars from the primary entrance to the primary exit can block all cars from entering the roundabout at secondary entrances. They have to wait for a car to enter at the primary entrance then take the secondary exit so before they can enter. I was once stuck at a roundabout for 5min due to a sports event in a nearby town creating a constant flow of south to north traffic, when I wanted to go from west to east. The roundabout useally worked perfectly fine, but was broken by the abnormal traffic. If that intersection had traffic lights, the impact on non south-north traffic would have been minimal.