Capacity Estimations for Type B Weaving Areas Based on Gap Acceptance

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Abstract
Although weaving areas are one of the major types of highway facilities that have long been investigated by many researchers, the estimation of capacity along weaving areas has not been well researched or validated. Most of the literature concentrates on methods for the estimation of the speeds of weaving and nonweaving vehicles and of level of service (LOS). The 2000 Highway Capacity Manual (HCM) weaving methodology includes methods for the estimation of capacities for weaving segments, which are based on the assumption that the density at capacity is the boundary of LOS E–LOS F, 27 passenger cars/km/lane. The objective was to develop a method for the estimation of the capacities of Type B weaving areas based on gap acceptance and linear optimization. In addition, traffic data were obtained from a site located on the Queen Elizabeth Way in Toronto, Ontario, Canada, and were analyzed to identify capacity. Field estimates of capacity were compared with those resulting from the new methodology and from the 2000 HCM methodology. It was concluded that the proposed methodology provides better estimates of the capacity of the study site than the 2000 HCM methodology does when the results obtained by both methodologies were compared with field observations. The collection of additional data is required to validate the proposed model for a variety of Type B weaving segments and for various traffic and highway design conditions.