Signal metering roundabout evaluation using fuzzy logic

Traffic congestion is the worst social problem in urban areas particularly at intersections. Intersections are used in typical traffic congestion areas for interrupted flow conditions. A roundabout is one of the intersection devices appropriate for low traffic volumes on collector roads and local streets. In recent decades, roundabouts have been used for local streets and roads which are carrying higher traffic volumes. They provide several advantages over signalized intersections including capacity enhancement, safety improvement and the prevention of environmental pollution. Roundabouts, however, are experiencing traffic congestion under unbalanced traffic conditions. When one approach has dominant traffic volumes compared to other approaches, entering vehicles on the dominant approach cannot enter the roundabout. This is because drivers cannot obtain enough gap acceptance value for entering. As a result, delays on the dominant approach can be longer. Therefore, this research will evaluate capacity, delay times and level of service at roundabouts comparing normal roundabouts, metering roundabouts and signal roundabouts using fuzzy logic.