Under light to medium loads, roundabouts are preferable to junctions with stop lights, as you rarely need to wait long to enter the roundabout. But under high

Under light to medium loads, roundabouts are preferable to junctions with stop lights, as you rarely need to wait long to enter the roundabout. But under high loads, they can cause starvation when there are no breaks in traffic along the more major road, so traffic cannot enter from the side road. When that happens, you need to add traffic lights to allow traffic to enter from the side road. But the traffic lights can be set up to only operate at busy times, so then you get the best of both worlds. Traffic lights on a roundabout at quiet times - yes, that's just stupid.