Innovative Smart and Self-Regulating Roundabouts

This paper presents two innovative smart roundabouts: the SSF-Roundabout (Smart Self-Regulating Roundabout) and the COM-Roundabout (Commutable Roundabout), designed for mixed traffic conditions involving Human-Driven Vehicles (HDVs) and Connected Autonomous Vehicles (CAVs). These novel road intersections employ adaptive control mechanisms that can dynamically adjust their configuration in response to varying traffic flow levels. SSF-Roundabout employs LOS (Level of Service) threshold-based adaptive flexible right-turn bypass lane activation, while COM-Roundabout adaptively adjusts the number of entry and circulating lanes to maximize capacity and minimize delays. The simulations confirm that both configurations provide substantial performance improvement compared with the conventional roundabout, as shown in particular by the results of the COM-Roundabout, described in detail, albeit at the expense of capacity/safety trade-offs. Finally, it is inferred that smart and self-regulating roundabouts are scalable solutions for future urban mobility systems.