The modern roundabout is a circular intersection with design features that promote safe and efficient traffic flow. It was developed in the United Kingdom in the 1960s and now is widely used in many countries, including the United States, where its use is growing.
At traditional intersections with stop signs or traffic signals, some of the most common types of crashes are right-angle, left-turn, and head-on collisions. With roundabouts, these types of potentially serious crashes are essentially eliminated because vehicles travel in the same direction and at low speeds.
Several studies conducted by Insurance Institute for Highway Safety (IIHS) and others have reported significant improvements in traffic flow following conversion of traditional intersections to roundabouts. Because roundabouts improve the efficiency of traffic flow, they also reduce vehicle emissions and fuel consumption.
Read the article at IIHS.