Climate change means roads should be built differently, UNH researchers say

Harrison Avenue in the South End is in poor shape. It is cracked, crevassed, and noticeably uneven.File 2009

Researchers at the University of New Hampshire say governments should start building roads with different and thicker asphalt now so they will be ready to withstand the effects of climate change in the future.

Pavements can crack and crumble under the stress of increased temperatures, said the study, which was published in May in the journal Transportation Research Record.

“If global warming continues, then we know temperatures will rise and pavement doesn’t respond well to increased temperatures. The hope is to find some answers now so cities and towns can plan for the future,” Jo Sias, one of the authors of a new pavement study and a professor of civil and environmental engineering at UNH.

As temperatures rise, asphalt gets softer and cannot handle traffic loads, Sias said in a telephone interview. Pavement materials are currently formulated with an eye to historical temperature data, but Sias said the current formulas will not stand up in the future.

“With future climates, [pavement] will fall apart sooner and it will be more expensive to reconstruct. Better to put relatively less money into the structure now to ensure it has longevity,” Sias said.

The study also suggests cities install thicker pavement as a solution because it will wear down more slowly. Areas with cooler climates use asphalt that is less durable in hot weather, so the researchers suggest those areas start using asphalt generally found in warmer places.

Researchers acknowledged that the work would cost more taxpayer dollars upfront but said it would be cost-effective. The new pavement would have more capacity to bear traffic loads before it cracks, so it will not need to be reconstructed as often, Sias said.

“[I]ncreasing the asphalt thickness to certain roads can be an added expense for cities and towns, but they point to considerable future savings of between 40 and 50 percent if done now rather than later,” the study said.

Changing the asphalt now and then maintaining it as the climate gets hotter is better than waiting, she said.

“Just like a regular oil change can help extend the life of a car, our research shows regular maintenance, like increasing the asphalt-layer thickness of some roads, can help protect them from further damage related to climate change,” Sias said.

UNH researchers also noted that bumpy roads cause cars to use more fuel, thus contributing to the climate change problem.

“As vehicles travel, the roughness causes those vehicles to use more fuel, so fuel efficiency decreases. The increased emissions from rougher pavements then contribute to accelerated change in climate,” Sias said.

When a road breaks down and needs to be reconstructed, it also costs people time and money, she also said.

The UNH researchers went to coastal New Hampshire to test how pavements would respond to simulated changes, but they suggested that their research methods could be used in other regions where roads will be affected by climate change.