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Solution to static traffic assignment problem with shock structures on a single origin-destination parallel road network


Speaker:

Prof. Peng Zhang

School of Mechanics and Engineering Sciences

Shanghai University, China

Date:    May 12, 2026 (Tuesday)

Time:   5:00 pm – 6:00 pm

VenueRoom 612B, 6/F Haking Wong Building, The University of Hong Kong

Language: Putonghua


Abstract

It mathematically indicates that shock structures are essential in static traffic assignment (STA) problems. The study is based upon the Lighthill-Witham-Richards (LWR) model or the theory of fundamental diagram, and takes a single origin-destination (OD) parallel road network as an instance, in which the user-equilibrium condition is satisfied.  Taking the total number of users on the network as the independent variable, it shows that there are no classical steady-state solutions to the problem for the number between two critical values, thus shock structures must be introduced to complete the solution in the interval.  Dynamic simulation of the LWR model on two ring networks is implemented to show that casually distributed traffic flow converges to analytical solutions, corresponding to the user number on the ring network. However, extensions of this study to more complex road networks are still challenging. For more details, see Z. Lin, P. Zhang, et al, Transportmetrica B: Transport Dynamics, 2024, vol.12, No.1, 2341012; Lyu, Y.P., Steady-State Solution on a Simple Single Origin-Destination Road Network based on LWR Model and User-Equilibrium Conditions, Dissertation, Shanghai University, 2022.


About the speaker

Professor Peng Zhang has a bachelor's degree in Mathematics from Sichuan University, a PhD and DSc in Mathematics from the University of Science and Technology of China. He is now a full professor at School of Mechanics and Engineering Sciences, Shanghai University, China. Professor Zhang has an educational and research background in the computational theory of hyperbolic conservation laws, and he focuses on traffic flow problems using the theory. His contribution to traffic flow problems mainly involves the mathematical theory, which includes the analytical properties in (1) the higher-order model; (2) the multi-class model; and (3) the models with discontinuous fluxes or inhomogeneous road conditions. Since 2003, he has published more than 50 SCI papers on such reputed Journals as J. Comput. Phys., Euro. J. Appl. Math., Numer. Meth. Partial Diff. Equ., SIAM J. Appl. Math., Appl. Numer. Math., J Comput. Appl. Math., Phys. Rev. E, Trans. Res. Part B, etc.



 
 
 

1st Research Workshop on Safety of AI-Driven Autonomous Systems


The first research workshop on safety of AI-Driven Autonomous Systems will be held at the Centennial Campus of HKU on May 6 morning. This workshop brings together leading experts from HKU, PolyU, Shanghai Jiao Tong University, Sichuan University, and HKPC to discuss topics including:

  • UAV autonomy and control

  • GNSS/SLAM localization

  • Safe motion planning

  • Smart mobility and low-altitude economy

  • Networked AI security and privacy

The event includes invited talks, technical exchange, and a tea break for networking. No registration fee is required. Please consider to register and join the workshop in person or online if you are interested in the topic!


Date: May 6, 2026 (Wednesday)

Time: 9:20 am – 12:20 pm

Location: Centennial Campus, Central Podium Levels - Two (CPD-2, The Jockey Club Tower) CPD-2.58, HKU or Online 


Please see the poster for the full schedule. You can register for the workshop by this link



 
 
 

Title: Air Pollution and Urban Mobility: Two Quasi-experimental Designs

Speaker: Mr. Yuan Liang (Department of Geography, Hong Kong Baptist University)

Date: Apr 28, 2026 (Tueday)

Time: 2:00 pm - 3:00 pm

Venue: Room 1010, CLL, Department of Geography, 10/F, The Jokey Club Tower, The University of Hong Kong

ITS Student Committee will provide a beverage for registered participants.


Abstract: I will share two studies that employ quasi-experimental designs to explore the bidirectional causal link between air pollution and urban mobility in urban China. The first study uses thermal inversion, a meteorological phenomenon, as an instrumental variable for air pollution to estimate the causal effect of air pollution on dockless bike-sharing usage. The second applies a difference-in-differences approach to evaluate the causal impact of fare-free public transport on air quality. The findings offer insights into the societal impacts of air pollution through the lens of urban mobility and hold implications for sustainable urban transport policies.


Bios: Yuan Liang is a Ph.D. candidate in the Department of Geography at Hong Kong Baptist University and a former visiting student in the Transport Studies Unit at the University of Oxford. His current research uses causal evidence to explore the linkages between climate change, air pollution, and urban mobility. His work has been published in Transportation Research Part A/D/E, Transportation, and Environmental Research Letters.




 
 
 
© 2026 by Institute of Transport Studies. The University of Hong Kong.
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