Toward the systematic diagnosis of freeway bottleneck activation

An active freeway bottleneck is a point characterized by the presence of queued traffic immediately upstream and unqueued (freely-flowing) traffic immediately downstream. It is shown that a freeway bottleneck's activation can be diagnosed definitively using archived inductive loop detector data. Once the bottleneck's location and time of activation were determined, potential signals of its activation were explored. It is shown that certain potential signals are evident immediately before upstream queue formation. As a result, it is suggested that these signals be used for systematic investigation of bottleneck behavior in either real time or in retrospect, on a more widespread basis.