An Empirical and Theoretical Study of Freeway Weave Bottlenecks

This report describes research which examined freeway weaving sections and the mechanisms that cause bottlenecks and trigger changes in the discharge flows. Changes in the spatial distributions of mandatory lane changes, particularly for Freeway-to-Ramp (F-R) maneuvers, were found to result in variations in bottleneck discharge flows. F-R maneuvers concentrated near on-ramp were found to be disruptive and led to bottleneck activations with discharge flow reductions. Traffic conditions in the auxiliary lane were found to dictate the spatial distributions of the lane changes. F-R drivers were motivated to perform their maneuvers nearer the on-ramp as a result of on-ramp flow reductions increasing the attractiveness of the auxiliary lanes. A micro-simulation model based on the observed lane-changing behaviors was developed and was able to reproduce the mechanisms of weaving bottleneck flows.