COLUMBIA — With the recent extreme heat, the Missouri Department of Transportation is advising drivers to be on the lookout for road blowups.
Three recent blowups, or road bucklings, have caused chunks of concrete roads to rise up to 12 inches above the rest of the road, said Dwane Vandelicht, MoDOT superintendent for Boone County.
Blowups happen when a period of extreme heat follows a time with substantial moisture, like this spring, Vandelicht said.
Moisture enters cracks in roadways, he said. As the sun shines and temperatures rise, the moisture turns into steam and creates pressure under the roadways.
Around 4:30 p.m. Saturday, the surface temperature of the pavement on U.S. 63 was about 125 degrees with no traffic, Vandelicht said. On a normal June day temperatures are usually below 115 degrees.
Blowups are the result of a combination of expanding concrete and steam pressure underground, he said.
"When you have heat, the molecules expand and they have to go somewhere," Vandelicht said. The heat tends to gravitate toward weak points in the concrete, where most blowups occur.
"It's got so much pressure" he said. "It can blow pretty good chunks of concrete."
Blowups can produce a variety of outcomes, Vandelicht said. Some are small and only displace little chunks of crumbled concrete. Some blowups can cause one side of the road to rise up to 12 inches.
Blowups have occurred on Providence Road near Hickman and Rock Bridge high schools and on U.S. 63 south of East Hinton Road, he said.
Most blowups occur at the beginning of the season when temperatures first begin to rise, he said.
However, drivers should remain cautious, MoDOT regional maintenance supervisor Larry Taylor said. Blowups can be severe enough to tear up the undercarriage of a car.
Drivers should look at their surroundings, he said.
It is especially important to look for pieces of concrete on the asphalt shoulder of roads, Vandelicht said. Chunks of white concrete are more noticeable on the black asphalt shoulders than they are on the road.
Taylor said there is no way to predict where and when blowups will occur.
"You never know where they're going to hit, when they're going to hit, how they're going to hit," he said.
With the weather conditions, drivers should "expect the unexpected," Taylor said. If Columbia gets more rain followed by more extreme heat, blowups are likely to continue.