Heat triggers buckled pavement in Twin Cities

A tropical air mass brought record heat, air pollution concerns and more buckled pavement to the Twin Cities Tuesday.

The National Weather Service says the high of 103 degrees smashed the previous record of 95 set in 2004. The sunny, hot conditions prompted the Minnesota Pollution Control Agency to issue an ozone health alert until midnight.

But, despite even warmer conditions than Monday, there were actually fewer problems on the roadways. Minnesota Department of Transportation spokesman Kent Barnard said of late Tuesday afternoon, about a dozen major pavement failures had been reported. That compares to 28 on Monday.

He said the combination of high heat and humidity can sometimes cause a violent reaction on concrete roadways.

"We did hear a report from a motorist that saw a section of pavement actually blow concrete into the air a ways, it's kind of like a mini explosion of concrete," he said.

Barnard says the road surface can heave upward when expansion joints fill with sand and debris, leaving no place for the pavement to expand.