Utah has one.  I think they are more common when the non freeway road has very high levels of traffic.<p>An even more efficient interchange is the roundabout interchange <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Roundabout_interchange" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Roundabout_interchange</a><p>The only problems with the roundabout interchange are that you need two different bridges spaced a distance apart which can add construction costs and they require more area than a standard interchange, although about the same as a clover leaf.