It's often disdained as poor man's paving, but officials at the Ohio Department of Transportation's district office in Lima, Ohio, have determined over the years that for certain lightly used highways, chip-sealing is an effective and efficient alternative to repaving.
As long as a road isn't used by more than 5,000 vehicles per day and its traffic is less than 20 percent trucks, chip-sealing has proven to be an economical way to lengthen the time between more costly paving projects, Bob Dillhoff, the highway management administrator at the Lima office, said last week.
Officials at ODOT headquarters in Columbus agree.
Along with starting a statewide initiative to identify roads that have chronic maintenance problems, the transportation department has directed district offices across Ohio to analyze maintenance programs to see which state highways in each district might be suitable for chip-sealing.
Chip-sealing involves spreading a layer of asphalt oil to seal the road surface and then embedding a layer of gravel chips in the oil to protect the seal and provide traction.
The Lima district, headquar-ters spokesman Andrew Gall said, has demonstrated "fairly good maintenance practices" that top ODOT officials now hope to replicate elsewhere.
"We're in the process of re-balancing our whole maintenance program," Todd Audet, the ODOT deputy director for the Bowling Green district office, told the Lucas County commissioners last month.
Chip-sealing has long been employed by municipal and county highway agencies for low-cost resurfacing, but its acceptance at the state level has been slowed by a belief that state highways deserve a higher standard of maintenance, Mr. Dillhoff said.
Yet 25 years of experience in the Lima district, covering Defiance, Putnam, Paulding, Hancock, Wyandot, Hardin, Allen, and Van Wert counties, have shown that chip-sealing renews roadway surfaces for as long as six years for just one-fifth the price of a resurfacing that lasts for, at most, 15 years, he said.
Paving currently costs about $33,000 to do one mile of one lane, while chip-sealing costs between $6,500 and $7,000 per lane-mile - and can be done by ODOT's own crews instead of hiring contractors.
"Now that things are getting so expensive, we have to look at every possible means to deliver service while saving money," Mr. Dillhoff said.
The cost-saving process isn't for everywhere. Heavy truck traffic pummels not only a road's surface but also its subgrade layers, and eventually even a moderately used roadway will develop subsurface flaws that demand deeper repairs.
This year, the Lima district is resurfacing about 220 lane-miles of roadway, spending about $1.5 million on chip-sealing and $7.5 million for repaving.
"We would never do [a chip-seal] on something with a large volume of trucks or traffic, like an I-75," Mr. Dillhoff said.
Chip-sealing irritates some motorists because within a few days of the work, some of the quarter-inch to half-inch stones that are used in the mix come loose and are kicked up by vehicles' tires.
Over the years, however, the highway administrator said, chip-sealing crews in the Lima district have become very practiced at not using any more stone than they need to cover the roadway, which minimizes the loose-stone problem.
The only other drawback to chip-sealing, he said, is that a freshly chipped road generates more friction noise than one paved with traditional hot-asphalt mix. That loudness persists until after a winter or two, during which snow plows wear down chips' rough edges.
"A year or two later, most people can't tell if [a particular road] was chip-sealed or paved," Mr. Dillhoff said.
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