This 2020 report by the Federal Highway Administration compares what the transportation industry calls modern roundabouts to newer turbo roundabouts that originated in the Netherlands.
FHWA studies have indicated that converting a traditional at-grade signalized intersection to a modern roundabout is expected to reduce the number of injury crashes by 78 percent.
The FHWA does recognize that there is a tendency for some 2 x 2 multilane roundabouts to experience higher frequencies of sideswipe. Some European countries have experienced good results by implementing a modified version of a multilane roundabout, known as a turbo roundabout. The turbo roundabout generally has the same characteristics as modern roundabouts but it uses different geometry and traffic control devices.
This FHWA report describes the characteristics of turbo roundabouts, highlights the design and traffic control features, their operational capabilities, and their potential safety benefits.