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(NC)-If engineer Susan Tighe has her way in coming winters, you'll see a lot less sand and salt on Canadian highways. But that's not a bad thing.
Black ice, that bane of winter driving, may be the last thing on Canadian minds in the dog days of summer. But the battle to keep winter roads safe has an environmental spillover that lasts through the whole year.
The problem is the approximately 5 million tonnes of road salt that runs off into lakes, streams and ponds, changing ecosystems and harming wildlife.
But Tighe, the Canada Research Chair in Pavement and Infrastructure Management at the University of Waterloo, may have a green solution. Her latest experiment, "permeable pavement," could put an end to black ice-without the salt.
"Traditionally, engineers try to keep water from seeping into the pavement, but we're doing the opposite," says Tighe. "If we can get the water to drain through the pavement into the ground, ice won't form, and we'll reduce the need for salt and sand."
One challenge, Tighe admits, is coming up with a material that can withstand traffic and exposure to the environment, but still lets the water drain through.
There, too, Tighe may have a green solution. As Canada runs out of good sources of stone-a fundamental element in pavement-Tighe and her team at the University of Waterloo are experimenting with creating permeable pavement out of sustainable materials.
One possible source is recycled concrete from old buildings and bridges. Another is asphalt from roof shingles.
"Every 12 years or so," she says, "Canadian homeowners get their shingles replaced. If we can harvest the asphalt from those roofs, we'll have safer roads-and we won't be just dumping the shingles in landfills."