Explaining Induced Traffic

Eric Jaffe at The Infrastructurist explains the non-intuitive reason why often removing freeways means less traffic.

1 minute read

June 7, 2011, 7:00 AM PDT

By Tim Halbur


Jaffe turns to a study by two economists from the University of Toronto, Gilles Duranton and Matthew Turner:

"Duranton and Turner analyzed loads of data on traffic, infrastructure, and travel behavior from metropolitan regions across the United States and found that 'vehicle-kilometers traveled increases proportionately to roadway lane kilometers for interstate highways.' For those who don't care for either academic abstracts or the metric system, the authors then parse their conclusion in pithier terms: 'roads cause traffic.' The basis for this confusing reality, write Duranton and Turner, is a three-pronged 'fundamental law of highway congestion' that explains why road construction can never keep pace with road congestion..."

Monday, June 6, 2011 in The Infrastructurist

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Wastewater pouring out from a pipe.

Alabama: Trump Terminates Settlements for Black Communities Harmed By Raw Sewage

Trump deemed the landmark civil rights agreement “illegal DEI and environmental justice policy.”

April 13, 2025 - Inside Climate News

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

April 16, 2025 - Diana Ionescu

Black and white photos of camp made up of small 'earthquake shacks' in Dolores Park in 1906 after the San Francisco earthquake.

The 120 Year Old Tiny Home Villages That Sheltered San Francisco’s Earthquake Refugees

More than a century ago, San Francisco mobilized to house thousands of residents displaced by the 1906 earthquake. Could their strategy offer a model for the present?

April 15, 2025 - Charles F. Bloszies

People walking up and down stairs in New York City subway station.

In Both Crashes and Crime, Public Transportation is Far Safer than Driving

Contrary to popular assumptions, public transportation has far lower crash and crime rates than automobile travel. For safer communities, improve and encourage transit travel.

April 18 - Scientific American

White public transit bus with bike on front bike rack in Nashville, Tennessee.

Report: Zoning Reforms Should Complement Nashville’s Ambitious Transit Plan

Without reform, restrictive zoning codes will limit the impact of the city’s planned transit expansion and could exclude some of the residents who depend on transit the most.

April 18 - Bloomberg CityLab

An engineer controlling a quality of water ,aerated activated sludge tank at a waste water treatment plant.

Judge Orders Release of Frozen IRA, IIJA Funding

The decision is a victory for environmental groups who charged that freezing funds for critical infrastructure and disaster response programs caused “real and irreparable harm” to communities.

April 18 - Smart Cities Dive