Traffic adaptive signal control at roundabouts

Modern roundabouts are designed to provide safe and efficient movement of competing traffic through roadway junctions. Under light-to-moderate demand and balanced traffic conditions, these roundabouts operate as designed. However, certain combinations of geometric and traffic conditions may compromise both safety and efficiency of a roundabout, requiring signalization to regulate traffic flow. Because signalization increases delay and stops at roundabout approaches, signal control should be activated only when needed and deactivated otherwise. This paper describes the conceptual framework of an adaptive system, which switches between signalized and unsignalized control based on prevalent traffic conditions. The paper also provides the results of computer-based traffic simulation used to verify this idea.