September 24, 2008

RUBBERSIDEWALK INC.

A 20-foot section of rubber sidewalk is used in front of each tree, but the rest of the sidewalk is traditional concrete.

Vancouver chooses Rubbersidewalk as green solution to city’s paving challenges

Jean Sorensen

correspondent

Vancouver’s inventory of park and boulevard trees, valued at $500 million, is challenging sidewalk construction crews to find new and better ways to pave over roots.

“Lifted (concrete) sidewalk is one of the most common tripping complaints,” said David Kidd, street operations superintendent.

Seeking a green solution, the city has installed 500 square feet of rubber sidewalk on West Eighth’s 2100 block, making Vancouver the second Canadian city to use rubber pavers over tree roots rather than use conventional concrete.

The pavers are made from recycled tires.

The City of Kelowna, in November 2005, became Canada’s first municipality to use Rubbersidewalk Inc.’s product.

The U.S. made product, though, has been used extensively in American major cities for the past decade.

Kidd said the city decided to use the pavers around mature trees rather than risk cutting their root system, which is normally done when roots interfere with concrete sidewalk excavation.

“What we have done over the half block is put down sections of concrete and then 20 foot sections (of pavers) around the tree,” he said.

Kidd said the pavers hook together with metal rods and can be incorporated into adjoining concrete sections.

Pavers can also be removed and reset again if tree roots shift the pavers or ground disturbance such as frost or an earthquake occurs.

There may also be a municipal need to gain service access.

The cost is about 20 per cent more than concrete, Kidd estimated, but added that concrete needs to be replaced about every seven years.

The company estimates the rubber paver’s life at about 20 years.

“This is a pilot project for us,” said Kidd, adding site monitoring will be done over the next year and if considered successful, other applications will follow.

Kelowna’s first application involved placing 400 square feet of rubber sidewalk in 2005. Sections were inter-spaced between concrete.

“This was an area where we had to place new sidewalk and if we had used conventional concrete, we would have had to cut a lot of the roots to excavate,” said Ian Wilson, Kelowna’s urban forestry supervisor.

He said the pavers can be placed above grade in cases, but can be placed with little or no excavation.

Since the original installation, the city has used them on several projects.

Kelowna has about 20,000 trees along streets and in parks (compared to Vancouver’s 500,000).

They are valued at $13 million.

“Trees are a valuable asset because they appreciate each year,” he said.

Wilson said there was concern that the rubberized pavers might prove slippery for pedestrians in winter, but there have been no problems.

Also, a city mini-dozer used to clear snow from walks in winter has not damaged the pavers.

Placing the pavers was initially a bit of a learning curve, said Wilson, but he added that it’s pretty straight forward.

The downside, he said, is the cost, which is about 30 per cent more than a conventional concrete sidewalk.

The units are shipped to the B.C. Interior from the U.S.

Rubbersidewalks Inc.’s Dan Joyce, a company principal and California sales representative, said recent studies have underscored the benefits of the product’s use.

A Santa Monica study found tree roots grow more naturally when pavers are used.

Joyce said that placing concrete over tree roots distresses them, causing roots to compensate by webbing up to the surface to grab run-off from the sidewalk as a survival technique.

This leads to the pavement cracking or lifting.

But, since the pavers allow water to flow into the ground, there is not that problem.

“We are now developing a new product, the next generation which is called Terrawalks,” he said.

“It’s a plastic and rubber hybrid for use in sidewalks but allows us to do it in more colours.”

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