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When Rubber Makes the Sidewalk

by Marcia Duffy
A concrete alternative

Lindsey Smith was taking a walk in her Los Angeles County neighborhood several years ago when she noticed red spray-painted “X’s” on dozens of old trees.

“For a second I thought—hoped—that the X’s meant that the trees were marked to be pruned,” said Smith, who was a filmmaker at the time. The next day she heard the buzz saws.

“I became enraged and ran outside, demanding to know why these gorgeous, healthy trees were being cut,” said Smith. The reason: the town was no longer willing to dish out money to fix the concrete sidewalks around 26 trees, which were being continuously lifted and cracked by the roots. She told the foreman to stop work immediately because there had been no public debate about removing the neighborhood trees, and she was going to inform the press. The story made front-page headlines.

Photo courtesy of Rubbersidewalks, Inc.
Before and after installation of Rubbersidewalks.

Because of public pressure, the town stopped the tree cutting. In the meantime, Smith learned that buckling of concrete sidewalks was a big dilemma for cities; municipalities were repeatedly replacing concrete because of tree roots. It was not only a problem of cost and aesthetics, it was also a safety issue.

“The more I looked into the problem, the more I realized that many cities did not know what else to do but to cut the trees down,” said Smith, “so I went looking for a solution.”

The solution came in the form of a product already being used in Santa Monica, Calif., created by Richard Valeriano, a public inspector for Santa Monica Public Works. Due to a flurry of lawsuits by pedestrians falling on heaved and cracked concrete, Valeriano created modular, rubber, sidewalk paver tiles to replace broken concrete sidewalks around the trees. Smith teamed up with Valeriano, got a grant to research the use of using recycled rubber tires to create the sidewalks, and Rubbersidewalks, Inc. (www.rubbersidewalks.com) was born in 2001.

Photo courtesy of Dennis Linn, village of Poynette, Wis.

During installation at site 1 in the village of Poynette, Wis.

To date, Rubbersidewalks have been installed in 90 cities throughout the country, including Washington, D.C., Los Angeles and Baltimore. This summer, the company will take on projects in New York City, which has changed its sidewalks specification to allow rubberized sidewalks. The company has saved over 1,000 old trees, says Smith, who is now CEO and president of the company. The company’s products are harder and more durable than the rubberized tiles placed under playground equipment.

“We’re saving trees left and right,” says Chris Bohnert, who works for the planning department in Michigan City, Ind., which installed 800 square feet of Rubbersidewalks in 2007. The department has ordered another 2,500 square feet for other sidewalk projects throughout the city.

Smith says that Rubbersidewalks not only solves the buckling issue caused by tree roots, it also provides environmental benefits, including helping with storm water runoff (since water can run through the seams) and lowering a city’s heat island effect, since it is cooler than concrete. The biggest environmental benefit is the use of recycled tires to make the tiles.

Saving trees, recycling tires

About 300 million tires are disposed of annually in the United States. In 2007, Rubbersidewalks used a couple hundred thousand of those tires. Granulated rubber is molded with polyurethane to create the tiles; about one tire is used per paver. A newer product, TerraWalks, clicks together like LEGO pieces rather than with dowels, like the regular Rubbersidewalks. This harder, but lighter, product uses a combination of 40 percent rubber and 60 percent recycled plastic.

Photo courtesy of Rubbersidewalks, Inc.

The product was tested for cold weather use in New Rochelle, N.Y., where snow was removed with snowplows, and salting and magnesium chloride were liberally applied.

Rubbersidewalks are more expensive per square foot than concrete. Michigan City’s Bohnert says that for his city, the advantages of Rubbersidewalks outweigh the cost, particularly in the cold climate where the cycle of freezing and thawing is brutal on concrete. The pavers’ flexible material moves with expanding earth and contracts when the soil contracts. Around trees, any “lifting” done by roots can be remedied by removing a tile, trimming tree roots and replacing the tile.

Cold climate uses

The product was tested for cold weather use in New Rochelle, N.Y., where snow was removed on the Rubbersidewalks using snowplows, and salting and magnesium chloride were also liberally applied. “If you push a steel blade into concrete it can get chipped because concrete is so brittle,” said Smith, but the combination of rubber and polyurethane, or plastic/rubber, gives the sidewalk resilience. “It’s made of rubber, but it is hard,” she said.

“We’ve gone through two winters without any problems,” said Dennis Linn, administrator for the village of Poynette, Wis., which has installed Rubbersidewalks in three locations around town. “We put the first installation in a high-traffic area to see if there would be any drawback—with lots of pedestrians on a main road approaching a school—but there were no complaints, and we didn’t have any problems.”

An added benefit is that when the snow is shoveled or plowed off the sidewalk, the rubberized sidewalks absorb more heat from the sun and residual snow melts more quickly than on concrete, said Linn. The only complaints they got were from skateboarders. “When they get to the rubber sidewalk, their skateboards slow down a bit—there seems to be more of a drag,” said Linn. The installation for 400 feet in various locations throughout the city cost $10 a square foot, or $4,000. “But, we’ve saved a lot of old trees, and so far there’s been no maintenance involved,” he said.

Linn noted it was a challenge finding a contractor to install the Rubbersidewalks. “We sent out requests to a broad range of contractors, from small concrete companies to landscapers who worked with hardscapes,” he said. “They either didn’t know what Rubbersidewalks were, or they didn’t want to take the time to learn how to install it.” Ziegler Landscaping was willing to do the job, and learned how to install the product by working closely with Rubbersidewalks, Inc. and following the installation manual. The company does offer training programs throughout the country for contractors to become certified in installing their product. There is a $750 fee for one person; $600 per person for others in the same contracting firm. The one-day training session includes training on installing the subbase and pavers, and how to plan and cut radiuses.

The downside

While there are many positives for rubberized sidewalks, there are a few drawbacks. It is difficult to install if the sidewalk has multiple curves, since a lot of cutting will be involved. “Cutting is time-consuming ... we have a protocol for this, but it is difficult,” said Smith. “It adds to the cost.”

The company also cautions care with oil products, such as automobile oils, tar and cooking fats, which can gradually damage the paver. Sulfuric acid (a chemical used in products to unclog drains) will damage the paver, and chlorine bleach will leave a white residue. However, organic materials (gum, ice cream, blood, tree sap, pollen, berry stains, etc.) can be hosed off with water or steam-cleaned. The pavers can be rotated or flipped over to reduce signs of wear.

While the product is guaranteed to last 10 years, Smith is more optimistic than that. “I think it can last forever. It does lose its color and get darker over time, but this is something that won’t ever fall apart,” she said.

The author is a freelance writer from Keene, N.H.