Event Date:
Content Type: News Item
Principal Investigator: Reid Ewing, University of Utah
Learn more about this research by viewing the two-page Project Brief, related presentations, and the full Final Report on the Project Overview page.

A new report from the University of Utah uses data to settle a debate that has been ongoing among transportation researchers since the 1990s: what are the effects of compact development on traffic congestion?

One camp argues that dense, compact development with a mixture of land uses will ultimately relieve congestion by encouraging fewer auto trips. On the opposite side, proponents of highway-induced, sprawling development argue that sprawl decreases congestion by funneling traffic away from dense areas, acting as a "traffic safety valve."

Led by Reid Ewing of the University of Utah and Shima Hamidi of the University of Texas at Arlington, this NITC study sought to address the question through cross sectional data. So which of these forms of urban development is better at reducing area-wide traffic congestion?

Surprisingly, neither.

Ewing and Hamidi arrived at the conclusion that development density—whether...

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Event Date:
Apr 14, 2017
Content Type: Professional Development Event

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Many agencies rely on trip generation estimates to evaluate the transportation impacts of land development in urban and suburban areas alike. Over the past decade, substantial attention has been paid to one national set of guidelines—the Institute of Transportation Engineers (ITE) Trip Generation Handbook (2014) and corresponding Manual (2012)—focusing in particular to improve the use of these data and supplementary methods for urban contexts. 

The purpose of this study is to explore the typical data provided in the Handbook, within the context of these new improved state-of-the-art methods. As ITE’s describes, “an example of poor professional judgment is to rely on rules of thumb without understanding or considering their derivation or initial context” (Institute of Transportation Engineers, 2014, p. 3). This research aims to improve the understanding of these data—still ubiquitously used across the US—to encourage increased engagement with their meaning, and following, to provide the users (e.g., engineering, planners, agencies, and...

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Content Type: News Item

For the first time, researchers have shown that installing light rail on an existing travel corridor not only gets people out of their cars, but reduces congestion and air pollution.

In the study, planners at the University of Utah measured impacts of a new light rail line in Salt Lake City (University Line) on an existing major thoroughfare (400/500 South). Their analysis showed that traffic near the University has fallen to levels not seen since the 1980s, even as the number of students, faculty and staff at the university has increased, and the commercial district along the corridor has expanded.

"This is the first study to document important effects of light rail transit on traffic volumes,” said Reid Ewing, professor of city and metropolitan planning at the University of Utah and lead author on the study. “Since the University TRAX line opened, there has been increased development in the 400/500 South travel corridor, yet traffic on the street has actually declined. Our calculations show that without the University TRAX line, there would be at least 7,300 more cars per day on 400/500 South, and possibly as many as 21,700 additional cars. The line avoids gridlock, as well as saves an additional 13 tons of toxic air pollutants. This is important knowledge for shaping future transportation policies.”

Andrew Gruber, executive director of the...

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