Transportation and its supporting infrastructure are among the biggest climate change challenges as the world moves away from fossil fuels, but one area often overlooked in conversations about electric vehicles or batteries or mass transit options is the condition of roads themselves.
That’s the focus of a new study from University of New Hampshire in the United States. Researchers there are looking at existing pavements and how they perform under increased climate stresses, including punishing heavy rains, coastal sea level rise and hotter temperatures. The study, published in the journal Transportation Research Record, looked at how asphalt road surfaces hold up across a range of temperatures up to 5°C in heat rise.
What they’ve concluded is that it makes more sense for cities and regional governments to spend the money on thicker layers of material – up to 32 percent thicker – because they’ll last longer. The upfront investment on certain roads will pay off in the long run with savings of between 40 and 50 percent.
“For agencies and towns, it is a balancing act to repair roads so we’re trying to find some reasonable action that can be taken now to help manage their infrastructure,” said Jo Sias, a professor of civil and environmental engineering at the university and co-author of the study. “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.”
The researchers looked at the seasonal and long-term effects on the pavement life cycle because the global temperature rise already is changing road conditions. Surfaces are buckling in the heat, or breaking up as waves breach coastal shorelines and batter roads. Heavy flooding rains are washing out surfaces and eroding underlying support structures. Higher groundwater levels mean changes in road stability, and water woes are occurring even on a good day: A separate NOAA study released this week found a record number of U.S. “sunny day” urban flooding episodes last year with only more to come.
“Pavement damage, now seen mostly in the spring and summer, is projected to be more distributed throughout the entire year,” said the New Hampshire team. They looked at local roads, yet they’re confident that the adaptation-focused assessment method they developed can be applied to most roads and highways across the globe. The results consider impacts through mid-century.
The researchers also warn that project planning, design, and construction expenses are likely to rise, adding to the overall coast of building roads that hold up to greater stresses. On the other hand, poorly designed and maintained roads have the potential to contribute to greenhouse gas emissions and global warming.
“It’s all about being strategic with the maintenance of our highways and byways,” Sias 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.”