Abstract:

During peak travel times traffic speeds often drop below the level at which flow is maximized. Transportation economists refer to such conditions as “hypercongested”. Hypercongestion has been studied using Macroscopic Fundamental Diagram models but these models typically rely on strong assumptions and abstract from details of the road network. The goal of this work is to examine the spatial and temporal evolution of hypercongestion during the morning peak on individual road links. Analysis is conducted using the traffic simulator METROPOLIS which was developed in the late 1990s to model travel mode, departure-time, and route-choice decisions on large-scale networks. METROPOLIS was recently upgraded to include individual point-to-point trips, trip chains, improved congestion modeling, and different vehicle types.

METROPOLIS is applied to a set of hypothetical road networks and regions of Ile-de-France to study two manifestations of hypercongestion. One is reduced speeds on upstream links that feed into downstream links with lower flow capacities. If prolonged, horizontal queuing on upstream links can lead to spillback that blocks intersections and access to links further upstream. A second manifestation of hypercongestion occurs when the aggregate outflow of vehicles from a study area drops below aggregate exit capacity due to conflicting movements at entrances, exits, and intersections.


Bio

Robin Lindsey is a professor emeritus at the Sauder School of Business, University of British Columbia. From 2010-2024 he held the CN Chair in Transportation and International Logistics. His research interests include traffic congestion, road pricing, urban public transportation, financing transportation infrastructure, and the environmental costs of road transportation. He has also worked on topics related to industrial organization including retail market competition, price discrimination, and predatory pricing.

Lindsey is a founding board member and past president of the International Transportation Economics Association, and an Associate Editor of Transportation Research Part B: Methodological. He is also coauthor with Kenneth Small and Erik Verhoef of the third edition of The Economics of Urban Transportation, published in June 2024 by Routledge.