Twice in a week, concrete chunks have rained down from the Gardiner Expressway onto roads typically teeming with motor vehicle and occasionally pedestrian traffic.

Fortunately, no one was hurt, but it could be only a matter of time.

The Toronto Star spoke with John Bryson, the city’s manager of structures and expressways, about the aging highway, its structural soundness and its future.

Is it safe to drive a convertible on Lake Shore Blvd. W.?

“I would. We’re confident that it’s very safe,” said Bryson, noting the city’s rigid maintenance schedule.

“I’ve got 600 bridges in the city plus the Gardiner to look after. All of them have reinforced concrete. I’ve had two incidents in one week, out of all those bridges. That’s very low risk. But I can’t guarantee that it’s going to be zero because of aging and the way reinforcement (reinforced concrete) behaves.

“If I’m sitting in my position, and I’m not sure if it’s safe, I shouldn’t be sitting here. That’s why I’m confident in saying that driving under the Gardiner is a safe condition for anybody.”

What’s being done to the latest stretch to experience crumbling concrete, the overpass at Parkside Dr. and Lake Shore Blvd. W.?

“We’re chipping some concrete that appears to be loose. We’re doing that controlled chipping to make sure that no more falls off.”

Bryson said the city does controlled chipping every year to prevent similar incidents from happening.

How big was the piece that fell?

The piece that fell was 6 inches by 6 inches and three-quarters of an inch thick. It fell in the middle of the road, but no vehicles were hit.

What’s causing the concrete on Gardiner to chip off?

“The nature of concrete is that it will have cracks from freezing and expanding from heat and salting,” Bryson said.

Are these incidents related?

“The city has 600 bridges; every once in a while they will decide to act together,” Bryson explained.

The Gardiner may be approaching its 60th year, but “it’s unfortunate when it happens twice a week.”

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Is the overpass’s structural integrity compromised?

According to Bryson, the concrete that came loose Thursday does not affect the safety of the structure because no damage was done to its internal structure.

What will the city do now to make sure it stops raining concrete in Toronto?

In the short term, Bryson said, the city will put up a protective cover to make sure no other pieces fall. But rehabilitation for the entire expressway is planned.

“We have one contract going out this year for a replacement at York and Jarvis on the Gardiner … we’re replacing the girders and putting on a new deck,” said Bryson, noting the estimated cost of this year’s project alone is $10.7 million.

What will be done to this stretch of the Gardiner in particular?

City engineers will inspect the area to assess whether it should be moved up on the list of scheduled maintenance work. But determining that will take some time.

“Parkside would have been four or five years down the road to be rehabilitated … I don’t think from what we’ve done today it’ll be moved up the list. It’s still probably five years off.”

When will that report be completed?

“Off the top of my head, we’ll get the investigation and the report by the end of this year.”

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