Virginia's Department of Transportation has invented a new blend of pavement that's supposedly better at absorbing sound. This new blend, called a Porous Friction Course, is undergoing testing on the Prince William County Parkway in Manassas.
"Basically, what you have is a skeleton-type structure on this type of pavement, and it's a lot of rock on top of rock with nothing in between. Just asphalt between the rocks," says VDOT pavement engineer Robert Wilson. "And it's porous, so it's supposed to absorb some of that sound, you know, the shock of the sound coming into is supposed to -- just like a sponge...keep it from going out into the area around us."
Standing next to the road, it doesn't exactly sound much quieter than other roads. Wilson says that noise is the echo effect from the trucks, but the pavement technology can't reduce that.
"What the pavement is testing is the noise between the tire and the surface of the road, where the wheel and the road meet. So that's the only reduction you're going to get from Porous Friction Course for quiet pavement," he says. "I think it's impossible to reduce the noise level on the vehicles themselves. The only thing we can effect with the road surface is the tire, where the road and the tire meet, you know, it's what all matters anyway right?"
Wilson says the research could reduce the need to build more concrete sound walls.
"And hopefully you can replace that with more shrubbery instead of a concrete wall, and with the reduced noise levels on the surface you can, you know, avoid the added expenses of building those sound walls," he says. "[There are] probably a variety of ways of looking at how it will affect construction going down the road."
The Commonwealth is planning to expand testing of this new quiet pavement to three more roads later this summer.
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