Researching a Capacity Model for Multilane Roundabouts with Negotiation of the Right-of-Way between Antagonist Traffic Flows.

摘要

This article summarizes a research program designed to assess operating conditions through capacity estimation\udat not-conventional roundabouts characterized by a central island with a large diameter and by two (or more)\udentering and circulating lanes. Although giving priority to vehicles on circulatory roadway is the nominal\udoperating rule, on-field observations highlighted that in some infrastructural schemes of the type considered in\udthis research drivers negotiate the right-of-way according to a consensus pattern that alternates between\udantagonist traffic flows, similarly to that observed at all-way-stop-controlled intersections. Considering the\udpeculiarity of the way of working at roundabout schemes being examined, as well as difficulties faced in the\udapplication of models based on gap-acceptance theory to evaluate performances, an analytical capacity model\udderived from field observations was proposed for multilane not conventional roundabouts.\udDrawing inspiration from the iterative procedure proposed for capacity estimates at all-way-stop-controlled\udintersections, a calculation algorithm organized in 5 subsequent computational steps was developed in order to\udevaluate capacity at each entering/circulating lane for the type of roundabouts examined in this research. Results\udcompared to those calculated by models for modern roundabouts show the effect on estimates of capacity raised\udby a more realistic operating pattern and indicate that the capacity model may be able to estimate parameters\uduseful for planning and design purposes