For drivers in towns and cities across Nebraska with spring, comes pothole season.
As temperatures fluctuate between 50 and freezing, roads can also fluctuate between smooth and bumpy – seemingly in an instant.
While drivers are sure to notice the amount of potholes growing during the early spring months, for the Fremont Streets Department the job of filling those holes seems never ending.
“We’ve been fixing what we can through the winter, and once the weather turns we can really start ramping up our efforts (to fill potholes), but potholes are obviously something we deal with every year,” Street Superintendent Mark Vyhlidal said.
According to Vyhlidal, one of the reasons why potholes seem to pop up in the spring, more than other times, is the weather patterns that befall Fremont and the state this time of year.
“It’s really because of all of that freezing and thawing,” he said.
In an essay that first appeared in the Colorado Springs Gazette, and subsequently appeared in-part in the Lincoln Journal Star, James Hagadorn, a scientist at the Denver Museum of Nature and Science, explained why potholes are a persistent problem particularly in areas with freeze-thaw cycles like Colorado and Nebraska.
According to Hagadorn, daily forays above freezing followed by subfreezing temps at night combine to wreak havoc on the roads. Mild winter and spring days allow water from rain and melted snow to flow through cracks in the pavement and enter soil that underlies the concrete or asphalt.
Once below the pavement, cool nighttime or next-day temperatures cause the water to freeze. Frozen water expands by about 10 percent — enough for a subsurface puddle to buckle the pavement upward a bit. Once the soil thaws, it slumps back to its original position, but the buckled pavement doesn’t.
According to Vyhlidal, in Fremont the weather also plays a role in how the Streets Department fixes potholes on streets throughout town.
“Right now we’re using a cold asphalt mix, but once the snow is out of the forecast for good, then we will move to using hot asphalt to fill them in,” he said.
Vyhlidal also said that although hot asphalt is more of a permanent fix, it’s not foolproof.
“Sometimes the cold asphalt can be more of a permanent fix, it really just depends on where and how bad the pothole is,” he said. “Sometimes we will have to fill the same pothole several times no matter what method we use.”
Along with fluctuating weather creating pothole problems, other factors include the speed at which vehicles drive on a particular road and the weight of the vehicles travelling on those roads.
According to Hagadorn, these factors are relevant because a vehicle’s impact on the pavement’s pre-existing weaknesses is what triggers or exacerbates potholes.
That impact mostly is governed by how fast tires hit the pavement, how much weight is riding on a tire and how hard the tire is. For example, truck tires, inflated to 100 pounds per square inch, are tougher on pavement than are most 32 psi car tires. Tires cooled by winter temperatures are more rigid and hit the pavement harder than do tires warmed by summer heat.
Today’s trucks are heavier, drive faster and travel more on local streets and highways than a half-century ago. The same is true with modern passenger vehicles.
For Vyhlidal, and the Fremont Streets Department, that means potholes also more likely to occur on busy thoroughfares in Fremont.
“We always see more on the busy streets, the main arterial roads throughout town,” he said.
He added that pooling water also increases the risk of potholes forming on streets and roads throughout Fremont.
“We get a lot of potholes at intersections and places where you find standing water,” he said.
According to Vyhlidal, along with receiving reports from local citizens about potholes the Fremont Streets Department also finds where problem spots are just like any other local drivers.
“We get a lot of reports, which are very helpful, but we also drive the same roads as everyone else,” he said. “So we will drive the streets and make note of trouble spots so we can send the crew out to fix them as well.”
Local residents who would like to report a pothole on a city street are encouraged to do so by calling the Fremont Streets Department at 402-727-2691.