Jorge Barrera
Northern News Services

Yellowknife (Nov 07/01) - Sidewalks are the ugly cousins when it comes to city-scapes with most municipalities spending more on roads to keep motorists happy.

However, things are changing for sidewalks.

A researcher with Ottawa-based National Research Council's Institute for Research in Construction recently released a study he claims could expand the life of the sidewalk.

In an interview with the Edmonton Sun, Blavant Rajani, a senior research officer with the institute, said sidewalks cost municipalities millions of dollars in repairs often caused by the harsh Canadian winter.

Rajani said stronger sidewalk construction could save cities money.

In Yellowknife the city budgets $55,000 a year in sidewalk maintenance and $165,000 on roads.

According to Norm Kyle, public works engineer with the city, sidewalks in Yellowknife generally last a long time.

He said sidewalks in the downtown core last around 30 years and most of the wear and tear comes from graders ploughing snow in the winter.

"Because for so many months of the year everything is frozen, sidewalks and pavement tend to last longer here," said Kyle.

Rajani and a team from the institute came up with a technique for sidewalks that could expand life for up to 50 years.

Rajani said the major problems with sidewalk construction stems from inconsistent foundation and the relationship between concrete and soil.

Rajani said workers often stamp foundations unevenly, concentrating on the centre creating uneven pressure on the concrete.

Rajani also said constantly heaving soil going in and out of thaw year after year puts terrible strain on the concrete.

Rajani and a team from the institute suggest placing a V-shaped layer of gravel beneath the walk and a layer of rigid foam insulation. They also suggested a cheaper alternative involving a 15-centimetre layer of gravel beneath the sidewalk.

Kyle said the department would take a serious look at the institute's findings.

"If it's something that is economic for us to do, we'll look at implementing it if it will solve the problem," said Kyle.

Kyle said the city doesn't have the same problems outlined by Rajani.

Sidewalks are often placed over rock so heaving isn't much of a problem. Kyle said the city uses 100 millimetres of foundation before laying down concrete.

Kyle said there are swampy places in the city but the ground conditions tend to affect both the road and the sidewalk demanding a full overhaul.

The city doesn't have problems with uneven foundations either, said Kyle.

"We don't do that," said Kyle. "We try to construct the whole thing, we over construct the road."

In new subdivisions the city builds the road and sidewalk on generally the same foundation.

"Generally sidewalks last as long as the road," he said.