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Professor Yue BAO of Vrije University Amsterdam:Leaving the Tub: the Nature and Dynamics of Hypercongestion in aBathtub Model with a Restricted Downstream Exit

Publish Date: 2019/11/04 17:20:22    Hits:

On November 4, 10:00-11:30 am, Dr. Yue BAO from Vrije UniversityAmsterdam was invited to visit our institute and gave an academic reportentitled "Leaving the Tub: the Nature and Dynamics of Hypercongestion in a Bathtub Model with a Restricted Downstream Exit" in the new main building A716.More than 30 professors and students from the School of Economics and Management and the School of Transportation participated in this academic report.

The macroscopic fundamental diagram (MFD) shows thathypercongestion can occur implying that a lower equilibrium travel time couldbe obtained at the same flow level. The bathtub model investigates howhypercongestion in urban areas arises when drivers canchoose their departure times and routes optimally. This paper investigatesequilibrium outcomes and user costs under the realistic assumption that thereis limited capacity to exit the bathtub. When the exit capacity of the bathtubis lower than the equilibrium exit flow from the bathtub, no additionalinefficiencies arise due to hypercongestion, whereas when the exit capacity ishigher than the equilibrium exit flows from the bathtub inefficiencies dooccur. The implication of this result is that with a restricted downstreamcapacity regulating hypercongestion may not be necessary because time gains inthe bathtub are lost in the queue at the exit.  

The purpose of this academic exchange is to carry out in-depthexchanges with relevant researchers on the theoretical basis of MFD and thebottleneck model. The contribution of MFD to traffic system modeling, largedata analysis and road network operation and planning and design is discussedfrom four aspects: the origin of MFD concept, data representation, theoreticalderivation and decision support.

Dr. Bao's logical and in-depth report has benefited us a lot.During the meeting, the teachers and students had an in-depth discussion withDr. Bao on some of the puzzles of the study, and the report was successfullyconcluded in a warm atmosphere.