On a scorching day last June, Chesapeake was forced to temporarily close the Great Bridge Bridge.
Daytime temperatures were high, and the air stayed hot overnight, which didn’t allow the bridge to cool down, said Earl Sorey, the city’s director of public works.
“Because of that extreme heat, the bridge, in essence, got to where it wouldn't open or close,” he said, “because the two sides of the bridge pushed into each other.”
Chesapeake is the only Virginia city to own and operate moveable bridges. Heat has always been a major factor in maintaining them, Sorey said.
But last year’s incident spurred the city to take more immediate action, such as actively monitoring vulnerable bridges and spraying them with water when temperatures hit 90 degrees.
“Fast forward to this summer, and we've got protocols in place so that we're more proactive rather than reactive,” he said.
Longer term, Chesapeake plans to replace the bearings to restore the 23-year-old bridge to its original tolerances. The span opens about 4,000 times each year to allow boat traffic on the Intracoastal Waterway below.
Extreme heat is often discussed in terms of exposure to humans, and with good reason. Heat has become the deadliest weather-related hazard in the country.
But hotter temperatures also increasingly threaten the infrastructure underpinning daily life in Hampton Roads.
“What we're seeing now is that our climate is changing, and our summers are changing,” said Luis Ortiz, an assistant professor at George Mason University and co-director of its Virginia Climate Center.
“That means that we're seeing these kinds of events happening more often than they used to, reaching those temperatures that affect that infrastructure more frequently.”
What happens during high heat
People shouldn’t expect roads and bridges to start falling apart during every heat wave, Ortiz said. Most infrastructure is built with a buffer to account for extremes.
But the goalposts are slowly shifting.
“If you have infrastructure that's designed to operate at a particular set of temperatures, and you are suddenly exposed to something outside of that range, then you might start seeing some impacts that you were not necessarily prepared for,” Ortiz said.
The biggest issue is thermal expansion. As material warms, it expands, then contracts again as it cools.
The most vulnerable spots are “where things are touching,” such as joints, fasteners and layers of roadway.
“If they are made of different materials or they have different shapes, then the rate at which things expand will be different. And that's where problems really start to arise,” he said.
That’s what happened at the Great Bridge Bridge, for example.
It also often affects train tracks. Where two pieces of rail meet and start to expand at different rates, they can deform and shift sideways, Ortiz said.
“If you're running a train very quickly, you're going to have to slow down the train because a very fast move to the left or the right can cause a derailment.”
Every summer in recent years, Amtrak has had to significantly slow down trains during high heat.
“As a precautionary approach, Amtrak may enact heat restrictions which require locomotive engineers to operate trains at lower speeds and can result in possible delays,” the company states on its website.
Ortiz said more often than full closures, people will likely feel the impacts of heat on infrastructure through delays and slower traffic.
The issue also puts workers at risk when they do repairs and maintenance, he noted. (Virginia earlier this year passed a law requiring new regulations to protect workers from heat stress.)
Handling impacts
Transit officials are looking for creative solutions.
The Metro in Washington, D.C., for example, recently started trying out white paint to reflect sunlight away from tracks. Shading connection points is another option, Ortiz said.
In Virginia, the largest manager of transportation infrastructure is, of course, the state Department of Transportation.
VDOT maintains more than 19,000 bridges and culverts, along with more than 60,000 miles of roadway.
Every state designs roads differently depending on its typical weather, said spokesperson Amy Friedenberger.
Most of VDOT’s road network is made of hot mix asphalt, which is more durable than regular asphalt and fairly resistant to heat.
Solid materials, including concrete, “can be a bit more challenging,” Friedenberger said.
Extreme temperature swings can cause concrete roads to expand, warp and buckle, compounded by high humidity.
“It’s sort of like the road coming up into a tent shape, like a little tiny mountain on the road.”
Fixes can include repairing affected joints, or, when the damage extends across a larger portion, the concrete slab would be replaced.
Friedenberger pointed to a recent viral video out of Texas, where a pickup truck went airborne after driving over one such buckle-hill.
“Luckily, that has not happened here,” she said.
But the industry is definitely paying attention.
“There is a lot of concern about making sure that everything, including our transportation infrastructure, is able to hold up against this extreme heat that doesn't seem like it's going to ease up,” she said.
Hampton Roads Transit oversees buses, ferries and light rail. The agency said in a statement that the vehicles and supporting infrastructure are designed to operate in a variety of challenging weather conditions, including heat.
“However, during extreme temperatures we monitor certain components and equipment for optimal performance and safety.”
Dominion Energy protects another vital piece of infrastructure: electric transmission lines.
One of the main ways heat impacts these is by accelerating their downward sag, according to Dominion spokesperson Jeremy Slayton.
“This is why our transmission line engineers design every line with a specific maximum wire temperature to provide safe clearances, or distance between the conductor and ground and surrounding areas,” Slayton said in an email.
He said the company also calculates the capacity of the wire at various ambient temperatures, in line with protocols adopted earlier this year by the regional electric grid operator, PJM.
In some areas, such as Northern Virginia, Dominion uses sensors for real-time physical conditions on transmission lines.
Ortiz said the good news is that making infrastructure more resilient is within our control.
“Because these are engineered systems, we can make decisions now that allow us to keep operating them in the future.”
