Heat causing 'explosions' on county roadways

Jeff Jarrell, maintenance supervisor in the Dexter MoDOT office, said there have been 26 incidents in the last three days of highway concrete joints expanding and causing an explosion. Jarrell said that one of these eruptions left a 12" fissure in the highway.

Sgt. Dale Moreland, information officer with the Highway Patrol, said the patrol worked six incidents beginning from 3 p.m. to 8 p.m. Sunday. Three of those locations were on US Highway 60 west of Dexter in Stoddard County. Three more were on Highway 25 stretching from just south of Dexter to north of Bloomfield.

MoDOT District Maintenance Engineer Mike Helpingstine said the problem is less common than in the past, but it remains a problem with concrete roadways when temperatures and humidity soar. Helpingstine said concrete expands and contracts at these seams in the highway, leading to a "rapid rising" He said he has seen the concrete rise as high as 18" to 20" in certain conditions.

MoDOT workers respond to a damage report as soon as they receive notification, according to Jarrell. He said crews use jackhammers to remove the damaged concrete and then a backhoe is used to clean out the resulting trench. Asphalt is then poured into the trench as a "temporary fix."

MoDOT workers were called to six locations on Highway 25 and three locations on Highway 60 Sunday. All three of the locations on Highway 60 were west of Dexter. Jarrell said each incident affected all four lanes of traffic on the highway, which meant there were 12 "blow-ups" to be repaired. The problems on Highway 25 were near the AF intersection south of Dexter, two more near the railroad overpass inside the city and two north of Bloomfield.

Jarrell said be believed the rainy weather in the past few weeks has been a factor. He said water that had built up under the roadways had not had enough time to evaporate before the high temperatures hit the area. He said that hot mix or asphalt roads were not as susceptible to these blow-ups. He noted that some of the problems on Highway 25 were minimized because hot mix had been laid over the concrete. Still, the concrete underneath the roadway expanded enough to cause a 12" fissure. The water managed to seep down into the concrete and not even the asphalt can stop the explosion when the temperatures rise as high as they have in recent days, said Jarrell.

Jarrell said MoDOT started using an eight inch wheel saw to cut the seams which are then filled with a polymer. He said the concrete has expanded enough that he has squeezed the polymer onto the road surface.

Moreland reported that there had not been accidents or injuries due to the problems on county highways, at least as of Monday.

Jarrell praised the Highway Patrol and county sheriff's office for their efforts. He said both agencies had worked around the clock to flag traffic at the scene of these fissures, rerouting them to the shoulders for safety. Jarrell noted that a 12" or larger fissure could pose a serious safety hazard to many vehicles.

Moreland urged motorist to use caution while driving on county highways during the current hot weather. Motorists are urged to watch for law enforcement traffic control and report damage to roadways to the Highway Patrol headquarters at 573-840-9500.