Top: In 2005, Seattle installed 375 square feet of sidewalk pavers made of recycled rubber; the pilot project was designed to protect existing street trees in the area. Bottom: In October, the city of Baltimore—which has more than 3600 miles of sidewalks—installed rubber sidewalk panels on a trial basis. Photos: Rubber-sidewalks Inc.

Oil and water. Nitro and glycerin. Cats and dogs. Some things just don't work very well together.

Take sidewalks and trees, for instance.

Putting in new or repairing existing sidewalks can be murder—literally—to existing trees if proper care is not taken to protect the roots. On the flip side, saplings planted next to existing sidewalks grow into towering giants with roots that turn neat squares of concrete into a mess of ugly chunks.

It's almost as if trees and sidewalks are mortal enemies hell-bent on destroying each other.

Now, a Gardena, Calif., company has come up with a solution that helps sidewalks and trees coexist peacefully.

Rubbersidewalks Inc. manufactures—as you might cleverly intuit from the name—sidewalks made of rubber. The product is made of recycled tires; each panel of sidewalk equals one tire rescued from a landfill. The surface is hard enough to walk, bike, skate, or Rollerblade on, but more forgiving and gentle to tree roots. Instead of breaking up, when over-ambitious tree roots grow underneath a rubber sidewalk, the panels flex. Also, unlike concrete, the panels can easily be lifted for root maintenance, then put back in place. If a panel of the sidewalk itself needs to be taken out, crews can do so without subjecting nearby trees to the harmful, jarring effects of a jackhammer demolishing the concrete.

Rubbersidewalks began producing their rubberized sidewalk panels in 2004. While the panels cost as much as three times more than the average concrete sidewalk, the company touts their ease of installation, durability, and kindness to the environment. The response in the two years since has been favorable: more than 60 municipalities across the country have placed orders—big cities like Washington, D.C., Boston, Seattle, and smaller burgs like New Rochelle, N.Y., are among the sites that now play host to the rubber walkways.

New Rochelle was among the first cities to try them out. Two years later, the sidewalks have withstood the test of time, enduring harsh winters and resisting discoloration from sunlight or deicers.

“Everyone benefits,” says Seattle project manager Liz Ellis. “The city will save money, we're piloting an environmentally innovative product, and we'll help Seattle's trees.”