More Lanes Mean More Emissions

As Seattle considers a plan to spend more than $17 billion on road and transit projects, the Sightline Institute looks at how the city's greenhouse-gas emissions would increase if a new land of highway is built.

1 minute read

October 8, 2007, 10:00 AM PDT

By Nate Berg

"We recently took a look at the greenhouse gas implications of building a new lane-mile of highway in a congested urban area. Our conclusion is that every extra one-mile stretch of lane added to a congested highway will increase climate-warming CO2 emissions more than 100,000 tons over 50 years. Those emissions are broken out as follows:

* Road construction and maintenance: 3,500 tons
* Net congestion relief: -7,000 tons [that's negative, folks]
* Additional traffic on the roadway: 90,000 tons
* Additional traffic off the roadway: 30,000 - 100,000 tons
* TOTAL: 116,500 - 186,500 tons

The relationship between road building and CO2 emissions has relevance far beyond this year's RTID debate. British Columbia is considering a massive roadway expansion in greater Vancouver, called the Gateway Program, which includes a controversial twinning of the Port Mann Bridge. And major road widening proposals occasionally rear their heads throughout Cascadia and beyond."

"The most curious thing is that some supporters of this sort of road expansion try to claim the environmental high-ground: adding lanes to crowded highways, they claim, will relieve congestion, which will reduce overall emissions."

"Our analysis shows this claim is bunk."

Thursday, October 4, 2007 in Sightline Institute

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