Print Email Facebook Twitter Hysteresis and the Unobserved Congestion Branch in the Macroscopic Fundamental Diagram Title Hysteresis and the Unobserved Congestion Branch in the Macroscopic Fundamental Diagram: Theoretical Considerations and Modeling Author Yuan, K. (Hefei University of Technology) Knoop, V.L. (TU Delft Transport and Planning) Date 2023 Abstract The macroscopic fundamental diagram (MFD) is developed to describe traffic operations aggregated over an area. The MFD is defined by network traffic states as a relationship between the accumulation of vehicles and flow or speed of vehicles. The concept of the MFD has been applied to model traffic dynamics and to design control strategies. For various applications (e.g., routing and departure time choices), the MFD is often assumed to be of a particular shape, consisting of two branches—a free-flow branch and a congestion branch. However, empirical observations show some inconsistencies between the theoretical and the empirical MFD. First, the empirical MFD only presents free-flow branch, i.e., the congestion branch is missing. Second, the MFD presents as hysteresis loop(s). This paper explores these differences, providing insights into urban network traffic dynamics. This work takes the travelers’ departure time choices and user equilibrium (UE) as starting points. We consider demand to be in UE in terms of departure time choices. Using this property of the demand profile, the paper proposes a closed-form expression for average density and outflow. Finally, we show some insights in the urban traffic dynamics: (i) an explanation of the hysteresis phenomenon solely from the perspective of departure time choices and UE and (ii) an explanation of why we hardly observe the MFD congestion branch in real life even in heavily congested networks. Our study shows that, for management purposes, the missing of congestion branch is a result of UE, rather than an indicator of congestion severity. To reference this document use: http://resolver.tudelft.nl/uuid:3ce3b0c7-89a0-4409-ab1c-b7973232810e DOI https://doi.org/10.1155/2023/8797109 ISSN 0197-6729 Source Journal of Advanced Transportation, 2023 Part of collection Institutional Repository Document type journal article Rights © 2023 K. Yuan, V.L. Knoop Files PDF 8797109.pdf 1.06 MB Close viewer /islandora/object/uuid:3ce3b0c7-89a0-4409-ab1c-b7973232810e/datastream/OBJ/view