Evaluating the Capacity of Freeway Weaving Sections

Abstract

The research described in this paper employed simulation modeling and empirical observations in an effort to (1) Identify the traffic flow phenomena that characterize freeway weaving section capacity; and (2) determine appropriate traffic flow rate values that reflect weaving section capacity. The INTRAS microscopic simulation model was calibrated and validated using empirical data collected at a weaving site. Increasing traffic demands were then sequentially input into repeated simulation runs to identify the boundary between uncongested and congested operation. Where a weaving section exhibits a typical level of both merging and diverging traffic movements, capacity is defined as a function of flows and lane-changing rates occurring in the vicinity of the weaving area’s merge gore. Where a weaving section operates with a relatively low total weaving demand, capacity is defined as a maximum rate of vehicles per lane. Validation experiments described in this paper suggest that the derived values of capacity apply to any one-sided freeway weaving section.