The Clinton Herald, Clinton, Iowa

March 1, 2014

Pothole problems imminent with deep thaw

By Brenden West
Assistant Editor

---- — CLINTON -- Potholes caused by winter weather have started to form within city and county streets and, according to road experts, it's just the tip of the iceberg as the Gateway region heads into what they're calling a "deep thaw."

Potholes form from the expansion and contraction of moisture that has seeped beneath the pavement. The water freezes and expands underneath, creating cracks in hard surfaces. When the water thaws and evaporates, the weakened pavement caves without the support of frozen liquid.

According to the Iowa Department of Transportation, this freezing and thawing weakens roadways throughout winter. Potholes become a common hazard during Iowa springs as a result.

This year could see an influx in potholes given the length and severity of cold weather in 2014.

"We're just getting into the start of when potholes start to show up," said Todd Kinney, Clinton County Secondary Roads Department director. "Potholes may be an increase in the number."

Clinton's city and county workers have already tackled some of the problems, replacing early potholes with temporary sealant. Given the colder-than-normal February, the region has yet to see what winter has left for the roads.

Kinney said he's most concerned for non-paved roads he oversees.

"The gravel roads are not an impervious surface like a paved road," he said. "Their sub-base is soil -- it gets its strength from the sub-grade dirt, so when that's saturated it becomes weakened. The paved roads can also be affected by the frost layered thaw."

This winter's greater snowfall presents more consequences. Roads departments have laid down higher quantities of snowmelt mixture, which further weakens the roadways.

Road crews will use temporary cold-mix asphalt to patch up the hazards, and will sweep through with permanent solutions when the weather is more suitable. The DOT has reported that in a typical year, the department spends approximately $3 million on primary patching projects for primary roads and $4 million on interstates.

"We'll address the paved road pothole issues with our normal approach," Kinney said.

As for driving advice, Kinney added simply, "Be cognizant."