We’re building roads to withstand last century’s climate

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Does it make sense to build something that will almost certainly end up wrecked before its useful lifetime is over? In most contexts, the answer is clearly "no," since doing so is a waste of money and resources. But lots of people seem to have a blind spot when it comes to planning ahead for climate change. North Carolina, for example, went through a protracted debate over whether it should allow people to build on sites that were likely to be under water. And the Trump administration recently cancelled rules that were intended to prevent infrastructure from being built where the ocean would rise to meet it.

But it's not just rising oceans that put our infrastructure at risk. According to a new analysis, current engineering practices have us building some roads that are already vulnerable to our warming climate, and the problem's only going to get worse. The results are likely to be more frequent repairs and a shortened lifespan. If the road is built to tolerate cold conditions that no longer occur, then it's possible that this involved an unnecessary expense.

The problem comes down to asphalt, which is a temperature-sensitive surface. It can crack if it gets too cold or undergoes freeze/thaw cycles, and it can partially melt if temperatures get high enough. There are different formulations, however, so the starting material can sometimes be tailored to tolerate the temperatures it is likely to face. Engineering best practices involve figuring out the likely high and low temperatures a region is likely to face and choosing an asphalt blend that is rated to tolerate those.

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