Field Evaluation of Lane Selection Strategies at Signalized Intersections

A critical element in assessing traffic performance at the individual lane level at signalized intersections is the knowledge of traffic volumes in each lane. Typically, turning movement volumes are available only for the entire approach, not for each individual lane. Collecting turning movement volumes by lane is costly and, for future year analyses, is unattainable. This paper summarizes the results of an empirical study of lane volume data that were collected at three intersections and provides an evaluation of six lane selection strategies used to estimate lane flows. The lane selection strategies are used as part of the subgroup approach for estimating saturation flow. This limited evaluation indicates that a lane selection strategy based on equal back of queue or cycle-average queue provides the best prediction of individual lane volumes in the field. This result is intriguing, given that at least three international capacity guides currently use an equal flow ratio or degree of saturation strategy for estimating lane flow and indicates a need for a larger data collection effort to confirm the results of this study.