Going in circles can be a good thing! According to a road safety study conducted by Nicolas Saunier, a professor at Polytechnique Montréal, roundabouts are far safer than intersections with traffic lights. The circular design enhances traffic fluidity by reducing speed without stopping it completely. High-speed lateral collisions are impossible, and the risk of accidents between vehicles is much lower. Added benefits include reduced brake noise, fuel consumption and pollution!
The circular design enhances traffic fluidity by reducing speed without stopping it completely.
But beware: not all roundabouts are created equal. For example, the more lanes there are and the larger the diameter, the greater the speed and the higher the potential for accidents. In addition, the conversion of traffic circles—the ancestor of the modern roundabout—can cause problems. Many traffic circles have been converted into roundabouts with no modification other than giving the right of way to traffic already in the circle rather than to entering traffic. The tangential approach of roads entering the circle encourages traffic to enter at higher speeds, resulting in more accidents and more dangerous interactions between vehicles.
This scientific study into the safety impacts of roundabout design is the first of its kind in Canada. Nicolas Saunier and his team studied some sixty roundabouts across Québec. The characteristics of the roundabouts were measured in the field or using Google Maps. The researchers also analyzed accident reports and processed more than 400 hours of video footage of roundabout driving. In fact, the team ended up developing video analysis software for identifying the impact of intersection characteristics. Nicolas Saunier’s work will help the Québec government to establish standards for the construction of safer roundabouts.