Downs Law Revisited: How and Why Expanding Roadways Reduces Congestion Despite Induced Travel

Date and time: March 3, 2025 | 12:00 pm – 1:15 pm (CDT)

Speaker: Alex Anas, PhD

Introduction: Chandra Bhat, PhD

Commentary: Steven Polzin, PhD

Archive: Flier

Registration: https://tinyurl.com/bdmb2b7n

About the talk

In 1962, Anthony Downs observed that expressways lowered congested travel times even though the expressways reached their maximum flow capacity. The talk will explain why expanding road capacity results in lower congestion after accounting for the additional travel demand that the lowered congestion induces in the short and long run. New road capacity induces more travel in many ways. These include switching from other travel modes, longer trips, new trips due to better access to opportunities, and new trips due to induced population and job growth. After accounting for the induced demand, vehicle miles traveled and the aggregate cost of travel can increase. Such increases reflect the beneficial effects of the lowered congestion.

Speaker

Alex Anas, PhD, Professor

State University of New York at Buffalo

Dr. Alex Anas is a professor of economics and affiliated with the Steven Still Institute for Sustainable Transportation and Logistics at the State University of New York at Buffalo. He was appointed at Northwestern University (1975-1991); and as a visiting professor at Stanford University (1981-1982) and the University of Illinois (1986-1988) and recently the MIT Center for Real Estate (2024). He is a fellow of the Regional Science Association International since 2006 and an awardee of the Walter Isard Prize in 2016. His research focuses on unified economic modeling of transportation, land use and urban development. He is the developer of RELU-TRAN (the Regional Economy, Land Use and Transportation), an urban general equilibrium model that has been used to study prospective congestion pricing in Chicago and LA and a public transit megaproject for Paris.

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