When workers chip-and-seal a road, motorists know what’s coming: rocks flying at their car for at least a few days.
But when the rocks continued flying off a southern Johnson County highway, it was clear something was wrong.
The chip-and-seal process, which lays a coating of oil and rocks to help preserve roads, is the equivalent of a four-letter word for motorists. The announcement by the state or a local street department that the process is being done is often met with criticism and then complaints about rocks flying up and hitting vehicles. But after three or four days the rocks will settle into the oil, and the road will become smoother — though never completely smooth.
When State Road 252 was chip-and-sealed in 2013, that didn’t happen; and state officials aren’t sure what exactly went wrong. Too cold of temperatures, the wrong kind of stone or a bad batch of oil could have been the culprit, said Harry Maginity, spokesman for the Indiana Department of Transportation.
Officials said other roads recently done are fine. The state has had no complaints about the condition of State Road 135, and State Road 44 is also staying sealed, despite the harsh temperature dips last winter, Maginity said. And they will continue using the process because it is a less-expensive alternative to repaving the road.
But the way they do the work might change, including possibly closing down roads while they are being chip-and-sealed. If the roads are closed, then the asphalt has a better chance to seal properly, Maginity said.
When workers chip-and-seal a road, oil is sprayed, and rocks or gravel are placed on top to keep water out of cracks and potholes. Vehicles will have better traction and can stop more quickly if needed with the extra asphalt on the road, Maginity said.
The state uses the technique to preserve and extend the life of a road for up to six years. The cost of using chip-and-seal on a road is significantly less than when the road is repaved, Maginity said.
In some instances, that can give street departments time to save up money for a full repaving project. In Johnson County, Rocklane Road was chip-and-sealed near Greenwood, and the county did not need to repave the road for 10 more years, highway deputy director Matt Olson said.
Chip-and-seal is a less-expensive option that at least keeps the road together for a few years, Olson said. Recently, the county needed to repave Franklin Road but didn’t have the money for the project. Instead, the road was chip-and-sealed, which put off repaving for another two years.
But the process doesn’t always work. About four years ago, the county chip-and-sealed a section of Whiteland Road, but the process failed to set properly. The stones had too much dust on them, so the sealant did not fix the road as it should have, Olson said.
During another project, the oil sprayer gauge was off, so it was spraying less oil than the gauge was reading, he said. The county had to find the problem, then chip-and-seal the road again.
“It could happen to anybody,” Olson said. “We’ve had bad luck before, too.”
Motorists complained about rocks flying up and hitting their windows after a chip-and-seal project on State Road 252 was finished. The state inspected the road and noticed that the asphalt was not sticking to the gravel. If the rocks do not stick to the oil, that can create a slick surface for drivers, and tar can get stuck on vehicles, Maginity said. The state had to grind down the road to get rid of the failed sealant.
What: Chip-and-seal is a process used to make the surface of roads last longer.
How it works: Workers spray oil, then place crushed rocks on streets to make them last longer.
What it does: The process seals the road so water can’t get in cracks or holes, and can prolong a street from needing repaving.