Motorists are being warned about some surprises in the road that could literally pop up in this week’s extreme heat. Bob Younie, with the Iowa Department of Transportation, says blowups are possible along older roads as thermal expansion forces the pavement to buckle and shatter.

“The roads that will have pavement blowups are those that are kind of worn out. They have some weak spots in them and that manifests itself as a pavement blowup,” Younie says. A number of such incidents have been occurring across the state this week as daytime temperatures have been reaching the triple digits. In some cases, a pavement slab can burst and fly a few feet in the air.

“Pavement blowup is kind of the common term, but most of the blowups are nowhere near that dramatic,” Younie says. “Most of them are just a bump in the road, but even a bump in the road is something that people have to be concerned about as far as driving safety.” In a typical year, Iowa D.O.T. crews spend up to 6,000 hours making temporary repairs of pavement blowups or replacing pavement sections, costing an average of $400,000 annually.

It’s been extremely dry early this summer, but Younie says moisture isn’t an essential ingredient for blowups. “Some people think that moisture or rain plays a part in pavement blowups and it might, but the chief contributing factor is that hot sun beating down on the road,” Younie says.

“Roads can be 130 or 140 degrees Fahrenheit very easily and that just causes an expansion and a blowup.” Motorists who witness a pavement blowup are asked to contact the nearest law enforcement agency to ensure traffic is routed around the blowup until work zone signage and repair crews are on the scene.