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

Cover CM Credits, Earn Certificates, Push Your Career Forward

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.

June 11, 2025 - Diana Ionescu

Metrorail train pulling into newly opened subterranean station in Washington, D.C. with crowd on platform taking photos.

Congressman Proposes Bill to Rename DC Metro “Trump Train”

The Make Autorail Great Again Act would withhold federal funding to the system until the Washington Metropolitan Area Transit Authority (WMATA), rebrands as the Washington Metropolitan Authority for Greater Access (WMAGA).

June 2, 2025 - The Hill

Large crowd on street in San Francisco, California during Oktoberfest festival.

The Simple Legislative Tool Transforming Vacant Downtowns

In California, Michigan and Georgia, an easy win is bringing dollars — and delight — back to city centers.

June 2, 2025 - Robbie Silver

Color-coded map of labor & delivery departments and losses in United States.

The States Losing Rural Delivery Rooms at an Alarming Pace

In some states, as few as 9% of rural hospitals still deliver babies. As a result, rising pre-term births, no adequate pre-term care and harrowing close calls are a growing reality.

3 hours ago - Maine Morning Star

Street scene in Kathmandu, Nepal with yellow minibuses and other traffic.

The Small South Asian Republic Going all in on EVs

Thanks to one simple policy change less than five years ago, 65% of new cars in this Himalayan country are now electric.

5 hours ago - Fast Company

Bike lane in Washington D.C. protected by low concrete barriers.

DC Backpedals on Bike Lane Protection, Swaps Barriers for Paint

Citing aesthetic concerns, the city is removing the concrete barriers and flexposts that once separated Arizona Avenue cyclists from motor vehicles.

7 hours ago - The Washington Post