The temperature is expected to swelter into the low 90s today with heat indexes in the 100s. Great news if you’re planning a post-work pool party, costly news if you’re the Iowa Department of Transportation (IDOT).

Thermal expansion is causing pavement blowups, which leads to buckled and shattered pavement along Iowa’s roadways.

The reason for the thermal expansion is twofold. When there is a wet period – which in case you hadn’t noticed Iowa has been having – followed by a hot week, conditions become right for pavement blowups, said Bob Younie, director of the IDOT maintenance office.

“Iowa DOT maintenance equipment operators spend 2,000 to 4,000 hours making temporary repairs of pavement blowups and another 6,000 hours replacing these pavement sections,” Younie said.

Pavement blowups typically cost the department $400,000 each year.

“Many of the blowups only result in a pothole or small chunks of concrete lying around the pavement joints, but they must still be repaired,” said Younie.

Just last evening there was a pavement blowup on Interstate 29. The blowups occur spontaneously, leaving motorists with little warning in the time immediately following the incident.

The IDOT urges motorists to pay special attention to pavement surfaces when driving on afternoons when temperatures exceed 90 degrees.