Roads, bridges and extreme head

By Tyson Fisher, staff writer

Here’s a riddle for you. When is hot hotter? The answer – where there’s pavement. And where there is trucking, there’s always pavement.

According to the Federal Highway Administration, there are about 2.7 million miles of paved roads in the United States. Truckers are unique workers in that they are tethered daily to pavement. Cities are giant “heat islands” of concrete. Even on a lonely highway in Nevada, truckers are bound to heat-absorbing ribbons of asphalt.

On a hot summer day, a highway’s surface could be 140 degrees. According to truckers who’ve tried it in the parking lot at I-80 in Walcott, that’s hot enough to fry an egg in five minutes.

While cooking on the asphalt isn’t science, dealing with extreme heat on the highway can be.

Truckers know a hot soft sticky road can hurt your fuel economy and slow you down. Like NASCAR drivers, they have long realized that when you’re driving at night, the highway surface is harder and mileage improves a bit.

What exactly is “extreme”?

According to a report by the National Cooperative Highway Research Program (NCHRP), infrastructure is designed to withstand certain types and frequency of “extremes” such as extreme heat, precipitation, floods or wind. The key word there is extreme.

NCHRP predicts that as average temperatures increase so will the extremes. More specifically, there is likely to be an increase in the frequency and duration of occurrence of what are now considered extreme temperatures, such as days above 90 degrees.

Just last summer, the South Dakota Highway Patrol posted images of a chunk of highway that had buckled under extreme heat. At around that same time, a traffic cam video was going viral after cars were going airborne on a Minnesota highway that had buckled.

“Temperature increases have the potential to affect and reduce the life of asphalt road pavements through softening and traffic-related rutting,” NCHRP says. “Extreme heat can also stress the steel in bridges through thermal expansion and movement of bridge joints and paved surfaces.”

Areas that typically have a cooler climate appear to be the most affected as they have never had to prepare for so much heat. A study in the Journal of Transportation Engineering on pavement design and performance in southern Canada reveals similar issues.

“Simulations for pavements in Alberta and Ontario show that temperature increases will have a negative impact on the pavement performance in the Canadian environment,” the study reports. “As temperature increases, accelerated pavement deterioration due to traffic loads on a warmer pavement was expected and observed. An increase in temperature would facilitate rutting because the pavement is softer. Pavement movement due to loads on a softer pavement would also result in increased cracking.”

Increasing temperatures will do more harm to our infrastructure than just physical damage.

In certain areas where high temperatures were less frequent, materials used to build roads and bridges will likely have a reduced service life if they are not rebuilt to adjust to more frequent heat. Taxpayers will be shelling out more money for increased maintenance or for new roads and bridges.

Higher temperatures can also reduce the time that can be spent maintaining and building our infrastructure. Building roads and bridges requires manpower. Construction companies must protect their employees from extreme weather, which leads to shorter hours when the thermometer nears triple digits. Ironically, the more triple-digit temps, the less time to fix roads for higher temps.

There is yet another component of our infrastructure that can be affected by rising heat: shipping costs. More specifically, the cost of refrigerated freight. Some freight doesn’t necessarily need to be cold, merely cool. A lot of cargo can require certain temperatures, including sensitive electronics. When the temperature inside trailers starts to get hotter and hotter, shippers may need refrigerated units when they otherwise did not. It’s something shippers are already thinking about. LL