Cheap asphalt and a wet winter led to a pothole-palooza in Nashville

You’re not imagining it.

Middle Tennessee roads had a lot more potholes this winter following numerous freeze-thaw cycles — and heavy precipitation.

Sections of pavement were bad enough to require “emergency” repaving jobs from the Tennessee Department of Transportation, which was forced to hire contractors to support its limited staff.

“There’s no secret,” TDOT spokesperson Rebekah Hammonds said about the situation. “We’re seeing them on almost all roads in the area.”

Courtesy Tennessee Department of Transportation

Heavy precipitation and persistent freeze-thaw cycles caused an unusually high amount of potholes and pockmarked roads this winter.

Climate change creates conditions for more potholes

Potholes form when moisture or water gets into asphalt, freezes and thaws. That expansion and contraction weakens the soft layer of pavement, and repeated impacts can then easily break off chunks.

Potholes are also affected by soil moisture under roadways. Wetter soil is weaker, and soil is the support system for roads.

This is especially concerning for coastal communities, where sea level rise is pushing up groundwater. But heavy precipitation events, which are becoming more common in Tennessee’s changing climate, can saturate the near-surface soil and raise the water table. Nashville experienced 9.5 inches of snow in January and had more than 8 inches of rainfall in February, according to the National Weather Service.

“With continued wetter periods, there may need to be a re-evaluation of what underlying aggregate, or what amount of underlying aggregate, should be used for our roads to mitigate the impacts of these wetter periods,” said Tennessee state climatologist Andrew Joyner. “Wetter winters are especially problematic because there’s minimal evapotranspiration, so the water can just stay around for longer, resulting in saturated soils days or even weeks after heavy rainfall.” 

‘Essentially a Band-Aid’

This winter, persistent cold temperatures made it hard for TDOT to complete effective repairs. Hot asphalt, which is considered a long-term solution, can only be installed at specific temperatures, and local asphalt plants remained closed during much of the winter, according to Hammonds.

Consequently, TDOT used cold asphalt mixes that have a short shelf life and eventually crumble.

“It is essentially a Band-Aid,” Hammonds said. “When you can’t get the holt asphalt mix, it’s really the only solution.”

Some spots patched as recently as February have opened back up or even widened, so TDOT has had to repatch or repave most roads.

Hammonds suggested TDOT is finally catching up on repairs, and that folks should expect better roads this spring.

“It’s a tough situation,” Hammonds said. “We never want to have unsafe conditions.”