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Dissertation/Thesis Abstract

Investigating freeway speed-flow relationships for traffic assignment applications
by Saberi Kalaee, Meead, M.S., Portland State University, 2010, 139; 1482734
Abstract (Summary)

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.

Indexing (document details)
Advisor: Figliozzi, Miguel A.
Commitee: Gliebe, John, Monsere, Christopher M.
School: Portland State University
Department: Civil and Environmental Engineering
School Location: United States -- Oregon
Source: MAI 49/02M, Masters Abstracts International
Subjects: Civil engineering, Transportation planning, Urban planning
Keywords: Flow, Freeway, Planning, Probabilistic, Speed, Travel time
Publication Number: 1482734
ISBN: 978-1-124-29694-4
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