Paving the Road To Fewer Carbon Emissions

Smoothly paved roads could save much more than our backs. A new analysis shows that they would save greenhouse gas emissions, time and money.

Keeping roads maintained could reduce carbon emissions from vehicles by up to 2 percent, shows the research published in the International Journal of Sustainable Transportation. These savings would more than offset the pollution that road construction generates.

Plus, better-paved roads would cut transportation agency spending by 10–30 percent, and would also save drivers 2–5 percent in fuel, tire wear, and repair and maintenance costs, the study found.

Transportation is one of the largest sources of carbon emissions in the world. Cars and trucks burn more fuel when tires have to work against the resistance on rough, bumpy roads. But the asphalt preservation and paving strategies used by highway agencies also generate emissions depending on the raw materials and processes involved.

To analyze the environmental cost of asphalt paving, researchers from Rutgers University used the Federal Highway Administration’s Long-Term Pavement Performance database to create models of pavement roughness after four common treatment methods. These include thin overlay, which involves placing up to 2 inches of asphalt on road surfaces; chip seal, which spraying asphalt emulsion and then putting down an aggregate; slurry seal, or spreading a slurry over pavement; and crack seal, filling cracks with rubberized asphalt and filler.

Next, the team used a vehicles emissions simulator to calculate the carbon dioxide emissions when vehicles moved on the different pavement models. They found that all the paving methods cut carbon emissions. Thin overlay gave the highest emissions cut of 2 percent because it reduces roughness, while the crack seal method gave the lowest 0.5 percent reduction.

Source: Hao Wang et al. Quantifying greenhouse gas emission of asphalt pavement preservation at construction and use stages using life-cycle assessment. International Journal of Sustainable Transportation, 2019.

Photo: davidpwhelan, Morguefile