Pretending that climate change can be solved by widening roads to keep cars from idling in traffic is dishonest and reprehensible, yet that’s exactly what Portland’s regional government is doing.

A new poll in Portland is promoting the discredited myth that cars idling in traffic congestion are a principal cause of climate change.

Portland’s regional government, Metro, is putting together the outlines of a $3 billion transportation funding measure, and hired a survey research firm to conduct a poll, supposedly to assess public attitudes about transportation. But in reality, the poll isn’t so much about assessing attitudes as it is trying to develop, refine and market a false and misleading message about the causes of climate change and what it will take to solve them. The poll repeatedly makes the claim that reducing traffic congestion will lower carbon emissions by reducing idling.

What this amounts to is publicly funded messaging to support climate change denial. It’s cloaking arguments for more road construction with a big lie about the role of traffic idling on carbon emissions, and a disproved theory that wider roads will reduce congestion.

The debunked idling myth

One of the favorite myths of highway advocates is the notion that an important cause of climate change is the carbon emissions from cars idling in traffic. If we could just widen roads so that cars never had to idle (or ideally,even slow down), we’d clearly lessen greenhouse gas emissions, right?

As we’ve reported at City Observatory, that myth has been repeatedly debunked by careful scientific inquiry. Widening roads causes the well known problem of induced demand–greater road capacity produces even more driving, and higher levels of carbon emissions. Induced demand means that highway widening projects don’t reduce traffic congestion, and therefore the imagined emission reductions from less idling never occur. The definitive evidence on this point comes from Metro’s own backyard, from Alex Bigazzi and Miguel Figliozzi, two transportation researchers at Portland State University. Their research shows that savings in emissions from idling can be more than offset by increased driving prompted by lower levels of congestion.  When you reduce congestion by whatever means, people drive more, and the “more driving” more than cancels out any savings from reduced idling. As they conclude:

Induced or suppressed travel demand . . . are critical considerations when assessing the emissions effects of capacity-based congestion mitigation strategies. Capacity expansions that reduce marginal emissions rates by increasing travel speeds are likely to increase total emissions in the long run through induced demand.

And its a problem that grows steadily worse over time–a more car dependent transportation system induces the additional decentralization of jobs, stores and housing, leading to longer trips. The variation in emissions across US metro areas for example, has everything to do with sprawl and car dependence, and nothing whatsoever to do with variations in time spent idling in traffic.

Its therefore simply dishonest to claim that wider roads and greater traffic carrying capacity will lead to greenhouse gas reductions.  Its hardly surprising that die-hard driving advocates would populate social media with this lie. What’s appalling is when a planning professionals propagate this myth.

Yet that’s exactly what Portland’s regional government, Metro, has done in a new poll it fielded in support of a proposed tax levy to support transportation. While it’s nominally pitched as neutral opinion research, its anything but.  It’s more of  a push poll, which systematically repeats the discredited claim that idling is a big contributor to climate pollution.   This thinly disguised “framing” would be bad enough if it were limited only to those who were surveyed, but its being widely disseminated by Metro as proof of public attitudes, and now its driving media coverage.

Willamette Week summarized the poll results as showing Portland residents don’t care much about climate, and want to widen roads.


Willamette Week’s reporting on the poll results perfectly delivers the message that its marketing mavens crafted:  We want to widen roads as a way to reduce greenhouse gas emissions.

Here’s the way that the project’s survey research consultants, FM3 summarized their findings in a presentation for Metro.


Do you favor or oppose “improvements”?

The question is based on an utterly false premise that reducing congestion by expanding capacity will result in lower emissions.  In addition, the choice of options is deeply biased:  one option is framed as “balanced” while the other is limited to “only” transit biking and walking.  One alternative is framed as providing improvements “roadway improvements” while the other alternative specifically rules out support for “improvements.”  (Characterizing one alternative as an “improvement” and the other alternative as ruling out an “improvement” is the very definition of a question bias).  As Charles Denison pointed out on twitter, the survey’s wording is an absurdly loaded choice.

Survey respondents were treated to a steady diet of repetition of this phony point in poll questions clearly designed to help fashion just the right rhetorical flourish to persuade voters.  Here are a couple examples of statements that respondents were presented (emphasis added):

In order to address the growing challenge of climate change and reduce carbon pollution, this measure would improve public transit to make it easier for people to choose not to drive; promote more use of zero-emission vehicles for transit; and reduce traffic and gridlock to cut back on carbon pollution from idling cars

A measure that protects clean air and reduces the pollution caused by idling cars and trucks, particularly along routes where people live and children go to school. Investments would help increase the availability of transportation options that preserve air quality and reduce the risk of lung disease and asthma.

It’s plain that what Metro is doing is market-testing the slogans, talking points and 30-second pitches that will be used to sell their bond measure. So what we’re seeing is just an advanced peek at a calculated plan designed to present this message about “widening roads to save the climate” as a way of convincing people to vote for a tax measure. And as Willamette Week’s coverage makes clear, this survey will serve nicely to propagate this myth to a wider audience.

What makes this especially bankrupt is that responsible analysts know that idling is not a major source of pollution or carbon emissions.  Metro’s 530-page Regional Transportation Plan which describes the region’s strategies for transportation and meeting greenhouse gas emission reduction goals contains no estimates of carbon emissions attributable to idling, no strategies for reducing idling as means to lower greenhouse gases, and in fact mentions the word “idling,” only once.

This kind of deceptive practice would come as no surprise if we were talking about marketing a fat- or sugar- laden snack as a healthy alternative. But in the face of an existential global crisis, the regional government is propagating a discredited myth to justify what are likely to be counterproductive investments in road widening. The first duty that any official owes the public is to tell the truth:  this polling is a dereliction of that duty and a subversion of the kind of frank and honest discussion we need to have if we’re going to tackle the climate crisis.