TOOLBOX ON INTERSECTION SAFETY AND DESIGN: DESIGNING AND OPERATING SAFER ROUNDABOUTS

This article on designing and operating safer roundabouts is from a set of conference proceedings on Intersection Safety: Achieving Solutions Through Partnerships (held in March 2004, Irvine, California). An introductory section discusses today's status of roundabouts in the U.S. and worldwide, and explains the historical evolution of the roundabouts. The author then explains the basic principles of roundabouts, their key design elements and safety aspects. The author covers the most critical elements of roundabouts, performance methodologies, and those aspects of roundabouts that are seen as issues or have been the subject of controversy. Specific topics covered include delays and capacities of roundabouts, signage and markings, and designing the roundabout for pedestrians, bicyclists and visually impaired users. Planners and engineers are encouraged to include roundabouts in their toolbox for intersection improvements, to perform preliminary engineering work to assess roundabout feasibility, and to compare their performance with other types of intersections whenever investments are considered for an intersection. The author emphasizes that well designed roundabouts can bring substantial benefits to our transportation infrastructure.