Title: Modeling Queue Spillback and Nearby Signal Effects in a Ro undabout Corridor
Abstract: ABSTRACT This paper will discuss two aspects of modeling roundabout corridors: (i) a lane-based model of queue spillback, i.e. blockage of upstream lanes by queues formed in downstream lanes and the resulting capacity reduction in those lanes, and (ii) a model of the effect of upstream signals on the capacity and performance of a roundabout located downstream of a signalized intersection. A roundabout corridor example will be provided to discuss both aspects. When capacity reduction of upstream lanes due to queue spillback results in oversaturated conditions, it is necessary to apply capacity constraint in determining exit flow rates of oversaturated upstream lanes, thus limiting the flows entering downstream lanes. These two elements are highly interactive with opposing effects. Establishing the relationship between upstream and downstream lane flow rates and identifying lane change implications are also important aspects of the model. Estimation of lane capacities, lane flows and lane queues for downstream and upstream approaches (including modeling of unequal lane use) is essential for reliable modeling of roundabout corridor (network) performance since these parameters are highly interdependent. The paper also discusses potential effects of nearby signalized intersections on a roundabout corridor. These include lane blockage by queues formed at downstream signals and bunching of vehicles arriving from upstream signals.
Publication Year: 2014
Publication Date: 2014-01-01
Language: en
Type: article
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