| Freeway areas in the vicinity of entrance and exit ramps are characterised by concentrated turbulence to the traffic stream on the mainline due to intensive vehicular interactions. Therefore, these areas, which include ramp-freeway merge, diverge, and weaving sections, are typically viewed as potential bottlenecks in freeway operations. The knowledge of capacity and operational performance at these critical areas is of utmost importance to various transportation applications including planning, design, operations and management. The current state-of-practice provides adequate procedures for performing capacity analysis at basic freeway sections. However, the procedures for freeway weaving sections and ramp-freeway junctions have been shown to be severely limited. At present, there are no adequate procedures that can be used to consider the impacts of traffic conditions or geometric features on freeway capacity and traffic performance.; Given this lack of guidance in the current practice, the research presented in this thesis is an attempt to develop a thorough understanding of freeway capacity and operational performance behaviour at those critical areas. Specifically, capacity and operational performance were investigated in terms of their interaction with key traffic and geometric variables that are believed to affect freeway operations. This understanding, while of particular importance to design and analysis applications, is not available within the current state-of-the-art.; Microscopic traffic simulation was the main analytical tool that was used to explore capacity and operational performance behaviour at those critical freeway areas. The traffic simulation model INTEGRATION was selected to perform the experiments involved in this research. Traffic behaviour from computer simulation was successfully validated against empirical data as well as against the well-accepted traffic stream models and theories. Exhaustive sensitivity analyses were then performed to establish the trends and patterns of capacity and operational performance behaviour at ramp-freeway merge, diverge, and weaving sections. These analyses involved the investigation of the impact of different traffic and geometric variables on capacity and performance within a full range of values established for each of these variables.; The research included in this thesis provides an extensive body of knowledge on freeway capacity and operational performance at ramp-freeway merge, diverge, and weave areas. This knowledge will have many practical and theoretical implications in traffic engineering and will provide valuable guidance to capacity analysis users particularly highway designers and traffic analysts. |
