Having grown up and learned to drive in the UK, roundabouts were normal, even back in the 1950s. The big problem I have with US ones is the tendency to try to go round the wrong way!.
We have half a dozen in this part of Washington, including two in Anacortes. One of the two in town has had a significant impact on the accident rate. It's at the entry to downtown from the State Route from I-5 to the San Juan Ferry terminal at the west end of town. It replaced a very confusing T-junction where the traffic on the "top" of the T was second to that doing the 90-degree turn. I understand that the accident rate there has been reduced by almost 70% since the roundabout was finished.. The second one is too new for anyone to assess its impact yet.
