Roundabouts are safer than any other at-grade intersection form because roundabouts have fewer conflict points, slower speeds, and easier decision making. Data from Europe, the United Kingdom, Australia, and the United States of America demonstrate improved safety over all other at-grade intersection forms in two distinct ways: 1) reductions in the total number of collisions, and 2) even greater reductions in injury producing collisions. Collision frequency and severity will decline for pedestrians, and motor vehicles.
The Insurance Institute for Highway Safety conducted a study published in the American Journal of Public Health. The study analyzed actual and expected crashes at stop and signal controlled intersections in rural and urban environments. Findings applicable to multilane roundabouts vs. signals include a reduction in all crashes of 32% and injury causing crashes of 68%. Injury crash reduction is greater than all crash reduction due to the elimination of most head-on, left turning across oncoming traffic, and right angle crashes. Head-on, left turning, and right angle crashes generate the highest energy and thus the highest number of injuries compared to rear-end and sideswipe crashes. Data for single and multi-lane roundabouts from other countries confirms the USA experience. Reductions in overall crashes range from 36% to 61%, and injury crash reduction ranges from 25% to 87%. (Roundabouts: An Informational Guide. Federal Highway Administration)
Pedestrian safety is also improved at roundabouts over traffic signals. Pedestrians using roundabouts are able to cross a much smaller roadway, consider traffic traveling only one direction at a time, and are exposed to traffic that is traveling at much slower speeds. Pedestrian crashes at British intersections occurred at the following rates: 0.33 crashes per million trips at flared roundabouts, and 0.67 crashes per million trips at signalized intersections. (Roundabouts: An Informational Guide. Federal Highway Administration) Clearly, signals are inferior to roundabouts for pedestrian safety.