For National Roundabouts Week, here are sample of some traffic circles. True roundabouts have significant horizontal deflection to slow motor vehicles, and do not have any traffic control devices such as stop signs. I do not consider multi-lane roundabout-like structures to be roundabouts, but unfortunately have not come up with a term to distinguish them.

Traffic circles are not roundabouts, at least not as implemented here in the Sacramento region. They are sometimes called mini-roundabouts, which is OK, but they should never be called roundabouts without a modifier. The eight photos below of traffic circles in the Sacramento region, most in the northeast portion of the central city, show some of the settings, and the wide variation in diameter. If the traffic circle is large enough, occupying a significant portion of the intersection, they do cause significant horizontal deflection and therefore slow traffic. Some of the traffic circles are too small, and do not force horizontal deflection and slowing. All of these examples have stop signs on one of the cross streets, so they do not meet the criteria of a true roundabout.

The safety of these structures is somewhere between a true roundabout (high safety) and a regular perpendicular intersection (low safety). Regular intersections are the location of most crashes, whether they are controlled by 2-way stops, 4-way stops, or signals.

See traffic calming measures for additional information on roundabouts and other traffic calming devices.

I have many. fewer photos of true roundabouts, in part because there are many fewer in the region, but I will post on those shortly.