Couple of things that go wrong with roundabouts: 2 lane roundabouts where the inner lane needs to give priority to then outer lane. The Netherlands does it a l

Couple of things that go wrong with roundabouts: 2 lane roundabouts where the inner lane needs to give priority to then outer lane. The Netherlands does it a lot better with lanes that 'tear off', and you migrate naturally to the outside line. Roundabouts on roads with lots of North/South traffic can cause people who come from East/West to have to wait forever as they can't just jump on the roundabout. As long as traffic is coming and can enter the roundabout they don't have to allow anybody else on it.