Hilton Head converted their two land roundabouts so that the outer lane is always exit-only (does not continue straight) and the inner circle functions as a traditional single lane rab. Works really well, even withs scads of tourists navigating the unknown pattern. I.e. The Villages
Hilton Head
Raleigh did something similar with a much smaller circle. It looks a bit crazy from above, and works because there is substantial signage before the circle to make sure you are in the correct lane.
