Moderator: 

Session Description
While full-sized roundabouts are a proven solution for addressing safety and mobility at intersections, they have become increasingly expensive relative to other intersection control types. An overarching theme of NCHRP Domestic Scan 23-01 was to increase the consideration of lower-cost roundabout solutions including mini and modular roundabouts. The Scan Team met with nine agencies to discuss their experiences with mini and modular roundabout planning, design, installation, and to gather lessons learned. Among the highlights were that mini roundabouts are increasingly being considered as viable alternatives on higher-speed, more rural roadways. Another important theme from the Scan was the high number of mini roundabout installations near schools—in addition to traffic calming, mini roundabouts can process the sharp peaks of school ingress and egress traffic more efficiently than some other forms of traffic control. In addition, the Scan documented that modular roundabouts are much less common than permanent mini roundabouts, with fewer than 10 known installations in the United States. Modular roundabouts have been installed quickly by a couple agencies at intersections with a large footprint, existing angle crash issues, multiple stop-controlled approach lanes, and traffic volumes well below the capacity of a signalized intersection. Both mini and modular roundabouts have information gaps slowing installation, including the lack of a proven capacity model for mini roundabouts and issues with project bid advertisement or even intellectual property for modular roundabouts. During this workshop, the Scan Team will pass along those findings to the audience and engage in a discussion with the audience on why, or why not, their agencies are using mini and modular roundabouts.