Officials believe heat may have caused falling Gardiner concrete

TORONTO – City of Toronto officials are speculating that the falling concrete from the Gardiner expressway could be cause by the record high temperatures.

Small pieces of concrete fell off the Gardiner Expressway on Wednesday, halting traffic at a major Toronto intersection for several hours, as crews worked to clean up, and check for major faults.

This is the fifth time that concrete has fallen from the elevated expressway in the last three months. Despite the repeated instances of concrete falling from the Toronto expressway, John Bryson, manager of the structures and expressways unit with the Technical Services branch of the city of Toronto, says that the Gardiner remains structurally sound.

“There’s nothing wrong with the structural capability of the Gardiner,” Bryson said.

With the extreme heat and high humidity on Monday, Bryson said, the concrete which is in contact with the steel girder exposed to the elements, may have moved more than regularly expected, in effect loosening the concrete and causing it to fall.

According to Bryson, cracks in the concrete of the 60 year old Gardiner, which at first “are very minute,” expand because of water making its way in, freezing during the winter, and thus expanding. The expanded crack then allows more water and salt into the crack, which eventually penetrates the rebar, loosening the concrete, and allowing it to fall.

University of Toronto professor David Lieberman is an architect who specializes in designing buildings. He says effects of the heat wave can be serious, and some cities may not be prepared.

“Toronto’s infrastructure was never designed for its climate, hot or cold. Future infrastructure has to be designed to accommodate temperature range, and it just wasn’t. As we developed these systems, we didn’t understand it.”

Lieberman won’t go so far as to say the pieces of concrete falling from the Gardiner or the glass panels crashing to the ground from condominiums are due to the heat, but he does say that deterioration to things like roadways has to do with temperature change over the years.

“Whether you’re detailing sewers or roads, you have to allow for the fact that materials move with temperature change. And each material moves at a different speed.”

Though Bryson does not dispute Lieberman’s claims, he points to the “expansion joints” installed on the Gardiner during its construction that allow it to expand, and contract with the weather.

The architect has personal experience with how this can impact construction.

“Yesterday I had to send a crane off the site because the hydraulics failed…the seal failed due to the extreme heat.”

Lieberman emphasizes the importance of future designs taking into account Canada’s “climate of extremes.”

“All of our servicing in a rapidly growing city is stretched to an extreme,” he says. “So there have to become appropriate systems of management of that infrastructure to react.”