Analytical Procedures for Estimating Capacity of Freeway Weaving, Merge, and Diverge Sections

Abstract

The paper identifies a total of 34 different weaving section configurations that are modeled while operating at capacity using the INTEGRATION software for a wide range of weaving section lengths and travel demand distributions. Subsequently, the simulation results are utilized to develop analytical procedures for estimating the capacity of Type A, B, and C weaving sections. The proposed procedures overcome the shortcomings of the 2000 Highway Capacity Manual (HCM) procedures by considering short (less than 150m) in addition to long weaving section lengths, by accounting for the source and distribution of weaving flow, and by ensuring that the capacity of a weaving section reverts to basic freeway capacity when the volume ratio is zero (no weaving flows) regardless of the weaving section length. The model can also estimate the capacity of merge and diverge sections at the appropriate boundary conditions. The paper demonstrates that the proposed model capacity estimates are consistent with field data while the HCM procedures tend to overestimate weaving section capacities significantly (exceeding 100%).