‘Diamond grinding’ roadwork on Highway 151 causing concern

FAIRFAX - A five-mile stretch of Highway 151 south of Fairfax is getting noticed by drivers - and not in a good way.

Last month, the Iowa Department of Transportation did what's called 'diamond grinding” to that section of the highway in both Linn and Benton counties. Diamond grinding, also called planing and grooving, is a method of trying to smooth out a roadway by cutting shallow grooves in the surface.

Some motorists didn't worry when road equipment 'roughed up” the surface of Highway 151. Allison Perlswitz, who drives that stretch frequently, expected the paving equipment next.

'I thought this was temporary that they were going to pave over it. But I guess not,” Perlswitz said.

New paving may come someday. But the nearly $250,000 job grinding the pavement was intended to serve as the final road surface until that day.

Cathy Cutler, a spokeswoman for the local DOT district, said this type of roadwork is done to try and put off the need for much more expensive replacement asphalt.

But Cutler admitted the plan has backfired a bit because the grooves cut in that part of Highway 151 in September should have been worn down a bit by traffic and warmer weather. The weather didn't get warm enough, long enough, for that to happen.

Cutler said the DOT will try an unusual tactic to smooth out the road a bit soon.

'We're going to send a snow plow down there and use the under body blade, the ice blade, on the truck to try to knock down some of those bigger bumps,” Cutler said.

Cutler said the DOT contract calls for no groove to exceed one half inch in height. But drivers in the area think some of the grooves are deeper than that.

There's also complaints the road produces a loud 'singing” noise from the tires that can be louder than a radio at highway speeds.

Cutler said the surface will eventually smooth out a bit. even without warmer weather. But it's not the same as new asphalt and isn't intended to be.