Want to reduce highway noise without retrofitting every vehicle with a quieter engine and tires? Grind the concrete with diamonds. That's what engineers have concluded after studying hundreds of highway surfaces across the United States, Canada, and Europe over the past 5 years. They found that by shaving off the peaks and irregularities that dot the surface of concrete pavement (top images) with a machine that is essentially a large drum encrusted with diamond dust, workers can reduce road noise by as much as 10 decibels—or nearly half. The technique can be applied to any concrete, no matter how fresh or hardened, pavement engineer Robert Otto Rasmussen of the Transtec Group in Austin, Texas, told attendees at a meeting of the Acoustical Society of America in Baltimore, Maryland, this week. So, he says, it "allows you to restore a quiet ride on virtually any roadway."