Portland State University. Department of Civil & Environmental Engineering
Miguel A. Figliozzi
Date of Award
Master of Science (M.S.) in Civil & Environmental Engineering
Civil and Environmental Engineering
1 online resource (xiii, 139 p.) : ill. (some col.)
Traffic flow, Highway capacity, Express highways
Developments in high resolution traffic sensors over the past decades are providing a wealth of empirical speed-flow data. Travel demand models use speed-flow relationships to assign traffic flows to network links. However, speed-flow relationships have not been revalidated against new detailed traffic sensor data. Therefore, it is necessary to revisit speed-flow relationships based on actual measured conditions on network links rather than assuming constant speed-flow relationships over entire highway network systems. Speed-flow relationships have been particularly difficult to calibrate and estimate when traffic volumes approach capacity, i.e. when the v/c ratio approaches one. This thesis empirically evaluates the speed-flow relationships for v/c < 1 using field data. For congested conditions (v/c > 1) a theoretical approach is taken. A new methodology to determine the distribution of the activation of bottlenecks, bottleneck duration, and bottleneck deactivation is proposed. This thesis is a new contribution to understand the stochastic nature of freeway capacity as well as bottleneck duration, activation, and deactivation. Unlike previous research efforts, this thesis studies speed-flow relationships at the lane level and later presents a method to estimate speed-flow relationships at the link level.
Saberi Kalaee, Meead, "Investigating Freeway Speed-Flow Relationships for Traffic Assignment Applications" (2010). Dissertations and Theses. Paper 33.