Generic Freeway Weaving Section Capacity Estimation Through Microsimulation

Freeway weaving sections are an effective and efficient manner to merge large traffic flows on the freeway road network. However the presence of disturbances caused by interacting traffic flows means that the weaving section capacities are limited in comparison to general theoretical capacities. This is a known effect which has been researched in the past decades with some success and has led to various models and assumptions for weaving section capacities. The determination of a generically applicable variable value of the capacity for application in a macroscopic model however is not as widely considered. Many macroscopic traffic models make use of a set capacity value. This value, when considering weaving sections, must be adjusted from the nominal freeway capacity value. In this paper research is presented into a methodology yielding a set of explicitly simple equations to determine weaving section capacity for application in such macroscopic traffic models. A deliberate effort is made to derive generic equations while considering the main influencing factors which affect the capacity of a weaving section. The results are validated with readily available empirical capacity estimations and are shown to give a good general estimation of the capacity of weaving sections. Also a comparison is made with the method applied in the Highway Capacity Manual 2010.