From UNH News Service: As the summer months heat up, so will the asphalt and other materials used to make roads, and climate change is just making it worse. Researchers at the University of New Hampshire say because of this one of the best ways to extend the life cycle of roads, and keep future costs down, is to increase the thickness of asphalt on certain roads.
“It’s all about being strategic with the maintenance of our highways and byways,” says Jo Sias, professor of civil and environmental engineering. “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.”
In their study, recently published in the journal Transportation Research Record, the researchers looked at the seasonal and long-term effects on pavement life, like climate-change-induced temperature rise and higher groundwater levels due to sea level rise and heavy rains. They looked at the changes in season length, increased flooding, average temperatures, projected temperatures and resilience based on those temperatures. As global temperatures continue to rise, road conditions will shift. The winter pavement season is projected to end by mid-century, replaced by a longer fall season.
Pavement damage now seen mostly in the spring and summer is projected to be more distributed throughout the entire year. Based on their analysis that looked at the wear and tear of roads, the researchers determined that a 7% to 32% increase in the asphalt-layer thickness might be the best way to maintain the service ability of some roads.
“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 Sias. “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 recognize that increasing 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% if done now rather than later. Along with the rise in cost of materials, there could also be other expense increases down the road like project planning, design, and construction. Environmental impacts could also be costly with rough pavements adding to increased greenhouse gas production, which has the potential to accelerate climate change.
While the study looked specifically at the impact of the changing pavement seasons and the increase in temperatures and flooding at a site in coastal New Hampshire, the researchers say the approach has the potential to be applied to most roads and highways both nationally and globally. The adaptation approach, of calculating the pavement layer thickness required to maintain a safe road reliability level, could provide the guidance to address the effects of rising temperatures and changing seasons on those byways.
Funding for this research was provided by National Science Foundation (NSF), New Hampshire Sea Grant, N.H. Department of Transportation and N.H. Department of Environmental Services.
I totally agree with these conclusions and as with most things the more robust something is the longer it holds up to stress. A 3” base coat with a 2” finish would seem adequate for city streets.
Quite a few years ago Rte. 132, known locally as Mountain Rd., was completely redone, from grinding down to dirt then applying the ground material as a base. Next came a layer of base coat and finally a finish coat of asphalt. This is a State maintained road and a good example of the proper way to redo. Yes it costs plenty but if you ride that road today it’s about as smooth as the day it was resurfaced, many years ago.
Blah blah blah…another fake climate change story…
There was discussion of the benefits of a full depth asphalt concrete pavement design since many years ago. I recall since back in the 70s. The compromise that has to be made is matching the tons of asphalt and money needed on roads with the actual money available now.
Maybe even more of a priority now is finding a way to hold back rising oceans and floodwaters due to the climate changes. If nothing is done, maybe there will be a shorter driving time to the beaches?