Version 1
: Received: 27 June 2022 / Approved: 28 June 2022 / Online: 28 June 2022 (05:08:23 CEST)
Version 2
: Received: 25 January 2023 / Approved: 26 January 2023 / Online: 26 January 2023 (03:42:51 CET)
Laval, J.A. Traffic Flow as a Simple Fluid: Toward a Scaling Theory of Urban Congestion. Transportation Research Record: Journal of the Transportation Research Board 2023, 2678, 376–386, doi:10.1177/03611981231179703.
Laval, J.A. Traffic Flow as a Simple Fluid: Toward a Scaling Theory of Urban Congestion. Transportation Research Record: Journal of the Transportation Research Board 2023, 2678, 376–386, doi:10.1177/03611981231179703.
Laval, J.A. Traffic Flow as a Simple Fluid: Toward a Scaling Theory of Urban Congestion. Transportation Research Record: Journal of the Transportation Research Board 2023, 2678, 376–386, doi:10.1177/03611981231179703.
Laval, J.A. Traffic Flow as a Simple Fluid: Toward a Scaling Theory of Urban Congestion. Transportation Research Record: Journal of the Transportation Research Board 2023, 2678, 376–386, doi:10.1177/03611981231179703.
Abstract
The analogy between the theory of phase transitions in simple fluids and vehicular traffic flow has long been suspected, promising a new level of understanding of urban congestion by standing on one of the firmer foundations in physics. The obstacle has been the interpretation of the thermal energy of the gas-particle system, which remains unknown. This paper proposes the flow of cars through the network as a viable interpretation, where the fundamental diagram for traffic flow would be analogous to the coexistence curve in gas-liquid phase transitions. Thanks to the power-law form of the coexistence curve, it was possible to formalize that the resulting network traffic model belongs to the Kardar-Parisi-Zhang universality class. The scaling relationships arising in this universality class are found to be consistent with West's scaling theory for cities. It is shown that congestion costs (delays + fuel consumption) scale superlinearly with city population, possibly and worryingly more so than predicted by West's theory. Implications for sustainability and resiliency are discussed.
Engineering, Transportation Science and Technology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Commenter: Jorge Laval
Commenter's Conflict of Interests: Author