The Gardiner Expressway is rife with deteriorating chunks of concrete that present a “significant hazard to public safety,” an outside engineering firm hired by the City of Toronto has concluded.

IBI Group found serious problems with the way city engineers go about identifying these problem zones in the underbelly and sides of the expressway. Its independent analysis uncovered sizeable cracks, spalls (pieces that have detached from a larger mass), problematic patches, and/or splitting in six areas where the city found “no signs of surface deterioration.”

But the report also cautions it is impossible to guarantee concrete won’t fall off in the future, no matter what precautions are taken.

This damaging report — finished just days before the two top bureaucrats in charge of the Gardiner file abruptly left their jobs — was released to the Star through a freedom of information request.

The first reports of concrete falling off the 60-year-old Gardiner Expressway surfaced in the summer of 2011. Chunks ranging in size from a toonie to a baseball have been documented in media reports. Half a dozen instances made headlines between May and July of this year.

MORE:What makes the aging Gardiner crumble?

In the months after, city staff and public works chair Denzil Minnan-Wong appeared in print and on television to assure the public the highway is safe.

But emails and briefings released to the Star indicate the problem is larger than acknowledged, with some confirmed and potential incidents never coming to light.

As recently as Aug. 29, staff confirmed, a chunk fell off at the foot of Parliament St.

In another case, a driver contacted the city on June 2 to report that a piece hit the top of his vehicle during a thunderstorm the day previous, at Don Roadway and Lake Shore Blvd E. He indicated he intended to sue. The city investigated, but found “no evidence of loose concrete or fallen concrete.”

This possible incident occurred three weeks before John Pandell reported that his two-door black Mercedes had been hit by concrete.

When first asked about the IBI Group’s findings, Councillor Minnan-Wong appeared irritated. He had not seen a copy. Several hours later, the public works chair said the city had work to do.

“We commissioned a peer review to determine if our visual inspection was sufficient. And it turns out that we were correct to do that, because we found it was insufficient,” said Minnan-Wong.

“We need to listen and take these comments and recommendations seriously and commit the necessary resources,” Minnan-Wong added. “I should have seen this earlier.”

Minnan-Wong said the committee is moving to increase capital spending on Gardiner repairs from $15 million to $35 million.

IBI Group’s independent analysis of the Gardiner identified three sections of highway to be in “poor condition,” with “very poor” being the worst classification.

The firm’s review — which was subcontracted to Coffey Geotechnics — was conducted over five days in late August and early September using sound technology. The City of Toronto relies on visual inspections.

That analysis revealed that “the areas of deterioration … vary greatly from the 2012 City of Toronto Visual Survey results for the areas investigated. This variance confirms the need for more intensive field investigations.”

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John Kelly, Toronto’s acting director of design and construction, said the fact the city commissioned the report shows it is being “proactive.”

Kelly said a key finding was that “hammer sounding,” which uses impact and then sound measurements to assess problem areas, is more effective than the city’s approach.

“We have done, every year, visual inspections of the Gardiner, which are generally done from the ground, to identify potential areas where we might have falling concrete,” he said. “It’s not surprising that they found larger areas of potential concrete spalling (loosening) by going up and physically hammering on the concrete than we determined from our visual inspections on the ground.”

The city’s current approach is to visually inspect the highway, then chip away at loosened material. When asked why the department wasn’t using the more sophisticated sound technology in the first place, Kelly said that “visual inspections were the first step — areas of concern identified through that procedure resulted in more detailed inspections and controlled chipping of loose/delaminated concrete.”

Several officials contacted by the Star pointed to funding pressures as a major factor in the city’s current approach.

As well as using sound technology, the report recommends the city adopt additional “investigative methods such as corrosion potential surveys, core exfraction, ground penetrating radar and thermography.”

It also suggested the city set up a dedicated entity with an associated budget to manage the file. Minnan-Wong was considering the suggestion, but his initial reaction was that it wasn’t necessary.

Contacted at his Toronto office Thursday, the report’s author said specific questions should be directed to the city, but Ted Brumfitt — an associate and manager of bridge engineering — noted that the city wasn’t doing a bad job.

“(The city has) been going through (making repairs), doing a pretty good job in how they’re doing that. But there are other things that they can extend. It comes down to managing risk,” Brumfitt said.

“All you can do is lower risk. You can’t eliminate it … you can take precautions.”

The report, dated Sept. 10, is only an interim version. The final review is expected before the end of the year. At that point, Minnan-Wong will discuss how to proceed with deputy city manager John Livey.

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