Roundabout interchanges are extremely common in the United Kingdom and Ireland with hundreds on the motorway network alone.
Roundabout interchanges are much less common in North America but have been built more frequently since 1995, to improve safety, and to reduce traffic delays and bridge widening costs.
A divided diamond, in which the minor road is separated into four intersections, rather than two, also acts like a roundabout interchange, but it is more square in shape and, typically, has traffic light control.
[1] Three-level stacked roundabouts are quite common in Britain because they use less land than other four-way junctions where both roads are grade separated.
However, they have lower capacity for turning movements – some have had direct-linking slip roads added later in an attempt to solve this problem.