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Venue: Room 115, College of Transport & Communications
Speaker: Dr. Wai Yuen Szeto is an Assistant Professor at the Department of Civil Engineering at The University of Hong Kong. He obtained his PhD at The Hong Kong University of Science and Technology in 2003. He was a Lecturer in Transportation Engineering at the Department of Civil, Structural and Environmental Engineering at Trinity College Dublin from 2004 to 2007. He then worked as an Assistant Professor at the Department of Civil Engineering at The University of Singapore for 2.5 years, and joined The University of Hong Kong in late 2009.
Dr. Szeto is authors of more than 80 refereed journal papers. The papers are related to dynamic traffic assignment, transport network design, public transport, network reliability, game theoretic approaches to transport and logistic problems, modeling land use, transport and environment interaction, and sustainable transport. He has been received the World Conference on Transport Research Prize, the Eastern Asia Society for Transportation Studies Outstanding Paper Award, the Hong Kong Institute of Engineers Outstanding Paper Award for Young Engineers/Researchers, the Hong Kong Society for Transportation Studies Outstanding Dissertation Paper Award and the Gordon Newell Memorial Prize.
Currently, Dr. Szeto is an Editor of Open Engineering, the Editor in Asian Region, International Journal of Transportation, an Area Editor of Networks and Spatial Economics, an Associate Editor of Journal of Intelligent Transportation Systems, Transportmetrica A and Transportmetrica B, Travel Behaviour and Society, and an Editorial Board Member of Transportation Research Part B, Transportation Research Part C, Journal of Advanced Transportation, International Journal of Sustainable Transportation, and International Journal of Traffic and Transportation Engineering. He is also a Guest Editor of 8 journals and reviewers of about 60 international journals. He received Certificate of Excellence in Reviewing from Transportation Research Part B and Part C in 2013.
Abstract: This seminar would propose link-based and approach-based variational inequality (VI) formulations for the stochastic frequency-based transit assignment with soft capacity constraints. An augmented route-section network representation is developed to address the covariance of in-vehicle travel costs between different sections of the same transit line. The augmented route-section network allows us applying the dynamic programming method to compute the mapping function of the VI, even if the correlation of travel times between route sections exists. To solve the problem, an extragradient method that only requires a mild assumption for convergence is proposed. A capacity paradox, a phenomenon in which the network maximum throughput may be reduced after providing new transit lines to a transit network or increasing the frequency of an existing line, is discussed. Numerical examples are provided to illustrate the effects of different parameters on the occurrence of the capacity paradox. Moreover, it is found that the capacity paradox may not occur simultaneously with the Braess-like paradox, a phenomenon in which providing new transit lines to a network may deteriorate the network performance in terms of the total effective travel cost.