February 26, 2010

FEATURE | Roadbuilding

Edmonton to deal with ‘bumper crop’ of potholes

RICHARD GILBERT

joc staff writer

The City of Edmonton is busy fixing potholes and expects to do more repairs in 2011 than in other years.

“I expect a bumper crop of potholes this year,” said city superintendent of operations for roadway maintenance Roland Hitchison.

“The number of potholes we repair depends on the kind of winter we have. This year we suspect that it will be higher than normal because the amount of snow is higher than normal.”

The number of potholes that form in a given year is determined by the amount of snow.

Pothole formation is driven by melting snow that seeps through cracks in the pavement and breaks up asphalt as it freezes and expands.

“We have also had some warm temperatures that have increased the freeze-thaw cycle,” said Hitchison.

“There have been some pretty severe swings in temperature that leads to nothing but grief when repairing potholes.”

In an effort to help reduce the impact of these cycles, city workers removed about 1.1 million cubic metres of snow from the roadway system in Edmonton by early February.

“Last year, we hauled 800,000 cubic metres of snow,” said Hitchison.

“So, we are already above that for this year and there is still about two months left in winter.”

So far this year, Hitchison said the city hasn’t repaired many potholes.

In January, city crews repaired about 4,000 potholes and those crews will repair about 400,000 potholes in a normal year, including the summer.

“They’re coming. They are not here yet, but they are coming,” said Hitchison.

“I will have a better idea in the summer, when the freeze thaw cycle goes away. I foresee there being well over 400,000 repaired this year.”

In the summer, Edmonton crews do most of the city’s road maintenance, which includes the use of gravel, asphalt and concrete. During the winter, these crews move into snow and ice removal.

The city owns an asphalt plant, which allows crews to use hot-mix asphalt to repair potholes in winter.

Some of this supply is contracted out in the summer.

There are 150 road maintenance workers employed with the city at a given time.

They work in shifts of nine to 10 people, which are rotated so that crews operate 24 hours a day, seven days a week.

The crews are split between snow removal and potholes crews in winter.

“The workforce is multi-functional, as well as multi-seasonal,” said Hitchison.

“I will use concrete finishers, who do sidewalk repairs in summer, to operate the plough in winter to remove snow from roads and sidewalks. Some of the people who operate the plows are the same ones who do the repairs. We can take a guy from a grader and then swing him to an asphalt crew.”

It is difficult to perform pothole repairs in the rain or when the snow is melting, which is why the best time to do repairs is in the summer.

However, repairs are still done in winter using a cold mix, which is a mixture of cold oil, aggregate and sand.

“This buys us time until we can come back and get a proper bond,” said Hitchison. “For our people, the pothole season is May and June.”

The average cost per month for pothole repair is about $250,000 and in 2010 the city spent $3.6 million to repair potholes.

In 2006, which is the last time Edmonton experienced this level of snowfall, city crews repaired 600,000 potholes.

Print | Comment