The biggest obstacle for roundabouts can be public acceptance, at least initially, experts say.
Drivers are conditioned that drivers on the right have the right of way, but in a roundabout, it's the other way around," Khattak says.
That's one of the big differences between what traffic engineers call the "modern" roundabout and the much-maligned traffic circles in New Jersey.
Altevogt says traditional traffic circles are large, high-speed interchanges where vehicles in the circle must yield to those entering the circle, which makes them prone to congestion. Roundabouts, on the other hand, are smaller, have slower speeds and make entering vehicles yield to those already in the roundabout, he says.