This course presents methods for analyzing the operation of an existing or planned roundabout. The methods allow a transportation analyst to assess the operational performance of a facility, given information about the usage of the facility and its geometric design elements. An operational analysis produces two kinds of estimates: (1) the capacity of a facility, i.e., the ability of the facility to accommodate various streams of users, and (2) the level of performance, often measured in terms of one or more measures of effectiveness, such as delay and queues.
Roundabouts may improve the safety of intersections by eliminating or altering conflict types, by reducing speed differentials at intersections, and by forcing drivers to decrease speeds as they proceed into and through the intersection. Though roundabout crash records in the United States are limited, the experiences of other countries can be used to help design roundabouts in this country. Understanding the sensitivity of geometric element parameters, along with the crash experience, will assist the designer in optimizing the safety of all vehicle occupants, pedestrians, and bicyclists.
Professional Development Hours: 3