(Dec. 1, 2017) Many people on Twitter were intrigued by the Portland City Council conversation Nov. 30, 2017 about adding variable priced tolls to area roadways. Some wondered why Mayor Ted Wheeler would say the City will not build any new freeways. Others wondered specifically about the statement by Multnomah County Commissioner Jessica Vega Pederson that affluent people drive more than people living on low incomes.

Here's some data and background on both points.

Mayor Ted Wheeler:

“It’s obvious to everybody that we live in a region that’s abundant with natural beauty and resources. We’re seeing that our economy is vibrant and continues to grow. One of the side effects of that good news is that we’re also seeing significant growth in congestion on our roadways. These same factors make Portland such a wonderful place to live, work and recreate but they also attract new residents. That of course includes increased housing and increased pressure on our roadways.

While I am mayor, I want to be clear, we’re not building any more freeways in the City of Portland. Congestion pricing not only funds and maintains our transportation system, but also is a very effective tool for managing the traffic that will continue as Portland grows and changes. We also can’t lose sight of the impact traffic emissions have on our public health and our overall environment. Air quality has been and will continue to be a key issue for me as mayor. We can’t deny that vehicles continue to be a source of pollution in the air we breathe. Today’s resolution is not only a statement of our values – advancing our community’s health, protecting our environment and achieving our equity goals – it is also a path forward to better achieve these goals.”

Wondering why it is that building new freeways or widening them without tolls can increase congestion rather than decrease it?

WIRED Magazine wrote an article, explaining why this happens:

WIRED Magazine, June 17, 2014: What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse

The magazine article is based on academic research, including this article published in a scholarly journal:

Duranton, Gilles, and Matthew A. Turner. 2011. "The Fundamental Law of Road Congestion: Evidence from US Cities." American Economic Review, 101(6): 2616-52.

This article provides an introduction to the concept and the principle arguments and debates, in layman's terms

Demystifying Induced Travel Demand, By Roger Gorham

For case studies on "induced traffic" and implications for climate change, see this national study:

Growing Cooler: The Evidence on Urban Development and Climate Change

Reid Ewing, Keith Bartholomew, Steve Winkelman, Jerry Walters, and Don Chen

with Barbara McCann and David Goldberg

Because we drive less, the Portland area's economy saves $2 billion a year

Portland's Green Dividend, 2007

Multnomah County Commissioner Jessica Vega Pederson:

"Congestion pricing can have benefits for both people who drive and people who use transit. And most importantly for me, it can have benefits for low-income residents as well. While tolls could be regressive, not all low-income people drive. Many low-income people don’t own cars, so tolls may not hurt the most vulnerable and may even help them, if reduced traffic congestion lets buses travel faster, improves frequency and expands bus lines – all of which should be part of a successful congestion pricing plan.

For the many low-income people who do drive, tolls may burden them, but tolls can generate revenue that we can use to offset costs for those low-income drivers.

What we don’t want to do is to assume that the current system of free roads benefits everyone equally. It doesn’t. Driving is expensive. It requires a car, gas, insurance, maintenance, registration fees, the list goes on. That’s why the affluent drive much more than the poor and take more advantage of our current road system.

We have the opportunity now to build a congestion pricing system that’s right for all of our community."

Looking for data on whether low-income people drive less than higher income residents?

Portland-area data from Metro

This table, from Metro’s 2014 Existing Conditions, Findings and Opportunities Report for the Regional Active Transportation Plan is based on the 2011 Oregon Household Activity Survey. It shows the people in lower income households (with incomes below $50,000) represent 46.4% of the overall population but represent only 34.8% of all driving. On the other hand, people in households with more than $75,000 annual income represent 35.2% of the population and 46.8% of all driving. Thus, it is people from the higher income brackets that seem more dependent on automobiles than those at lower wages.

Also from Metro:

People that most need inexpensive transportation options often have the least access to them.

"People with low incomes and people of color depend more on means other than driving alone. Transit is especially important to ensure mobility for these communities, who are twice as likely to be frequent transit riders as higher-income persons or white people."

- From "You are here: A snapshot of how the Portland region gets around."

Census data

An article in Governing Magazine included Census data that showed Portland transit commuters earned 20% less than all workers (excludes non-workers). See chart here where you can select the city.

Governing Magazine, Feb. 25, 2014: Public Transportation’s Demographic Divide





Other, earlier study showing high income drive twice as many miles a year as low-income.

A Purdue University study also found that higher-income people drove roughly twice as many miles a year as low-income residents.

UPDATING PROCEDURES TO ESTIMATE AND FORECAST VEHICLE-MILES TRAVELED

Jon D. Fricker Professor and Raymond K. Kumapley Graduate Research Assistant School of Civil Engineering Purdue University

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The Portland Bureau of Transportation (PBOT) is the steward of the City’s transportation system, and a community partner in shaping a livable city. We plan, build, manage and maintain an effective and safe transportation system that provides access and mobility. Learn more at www.portlandoregon.gov/transportation

(Updated: March 7, 2018)