Appropriate deceleration on approaches to roundabouts is primarily accomplished through the use of applicable geometric design principles. However, traffic control devices (specifically signing and makings on approach) also serve a vital role in communicating to the approaching driver what speed profile should be anticipated. This report provides a resource for engineers to identify and select appropriate speed-reduction treatments for high- speed approaches to roundabouts. The research examines best practices and techniques that are the most effective at lowering approach speed.
