How to green highways

Highways, parking lots and other paved surfaces represent the least sustainable development, right?

Not always.

Writing in the Journal of Cleaner Production, Massachusetts Institute of Technology researchers found that many factors determine whether pavement is contributing more or less to climate change.

“It turns out that the design and maintenance of pavements indirectly impact the environment,” said Jeremy Gregory, the study’s co-author and executive director of the MIT Concrete Sustainability Hub.

“Some of these impacts include the way that pavements impact climate through their reflectivity, through the absorption of carbon dioxide over time through the paving materials, and by how they affect the fuel consumption of the vehicles that drive on them.”

Pavement-vehicle interaction, or how pavement affects vehicles’ fuel consumption, is perhaps the greatest factor in how many emissions arise from a highway or road, Gregory added.

“The rougher a pavement is, the more energy dissipation there is in the shock absorber system of a vehicle,” he explained. “A vehicle must then consume more fuel to overcome this additional energy dissipation. We refer to this as excess fuel consumption.”

If roads are slightly inclined, vehicles also guzzle more gas.

“The weight of a truck makes a small indentation in the pavement so that the vehicle is always driving up a very shallow hill,” said Gregory. “Like roughness, deflection also causes excess fuel consumption.”

In California, cars might be guzzling an additional 1 billion gallons over five years due to pavement issues that could be corrected, the paper found.

Image credit: Maxx Girr via Pixabay

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