It's called "tar and chip," "oil and chip" and "seal coat," and probably some less-printable things by those who have to drive on it.
By the time summer's out, the Pennsylvania Department of Transportation expects to spread the mixture on 183 miles of roads in Allegheny County, more than doubling what was done last year.
Many motorists don't like the pinging and clanging and occasional paint or windshield damage caused by gravel or oil coming up from the freshly treated roads, but PennDOT officials say it's a necessary part of maintenance in a time of tight budgets.
"Of course our preference would be to use the hot-mix asphalt, but financially it's not feasible to do that and stay on our program," said Jeffrey M. Karr, PennDOT assistant district executive for maintenance.
The cost of seal coating is $25,000 per mile of two-lane road, compared with $350,000 for asphalt, he said.
The treatment seals cracks, keeping moisture from penetrating and causing potholes, and the texture provides better traction in wet weather.
It's also faster than resurfacing with asphalt, and when the pinging goes away in a few days, "it gives you a better surface to run on," Mr. Karr said.
Less-traveled roads in rural and suburban areas typically are chosen for the treatment. It is not suitable for areas with major developments or heavy truck traffic, he said.
In about an hour last week, a PennDOT crew sealed a stretch of East Willock Road in Whitehall and Baldwin Borough.
Oil-and-chip crew veterans Rich Staub, Nick Micale, Nick Vivaldi and Duke Grego manned the equipment -- a tanker that coated the road with an oil/polymer mixture, 0.28 gallons per square yard, followed closely by a stone chipper, pushed by a dump truck driven in reverse, that spread a uniform coat of gravel -- 18 pounds per square yard. That was followed by rubber-tired rollers to pack it.
"Some of these guys have been doing it for 20 years," county maintenance manager Bob Crawford said. "They like the product. They believe in it.
"You have to drive slow on it [at first]. It's a tremendous product we use. It saves our roads."
The crew wasn't exactly greeted as conquering heroes by the locals. One woman in an SUV made her statement by stomping the gas pedal to spew the newly laid gravel.
Later, some residents were critical.
"For years and years they've been doing this. Everyone around us is getting the good asphalt and we get the tar and chips even though we all pay about the same amount of taxes," said Sherwin Houser. "It's not right. I think we're getting second-class service."
"It's just a mess out there," said Ray Englert, who said gravel was strewn on driveways and in yards.
He said the road surface "is an improvement from two weeks ago," but questioned how long it would last.
"As you drive up and down, your afraid of all those stones going up under your car," said Patricia Weil, an East Willock Road resident since 1972.
She said the road was "pretty bad, pretty bumpy" before the treatment, and said she was willing to wait and see the end results.
"I don't have a lot of choice, do I?" she remarked.
PennDOT spokesman Jim Struzzi felt the same way. "As resurfacing dollars decrease, seal coating and crack sealing will increase," he said. "We don't have any choice."
PennDOT plans to treat four roads in Collier this week: Nike Site Road from Thoms Run Road to Noblestown Road; Greg Station Road from Walkers Mill Road to Franklin Street; Hilltop Road from Thoms Run Road to Route 50; and Ewing Road from McMichael Road to Main Street.
Jon Schmitz can be reached at firstname.lastname@example.org or 412-263-1868.