Temperatures too cold for salt, making roads slick

ABOVE: Black ice is believed to be responsible for a 10-car pileup on the Gardiner Expressway Friday morning

TORONTO – Following a series of early morning accidents across Toronto, many drivers may be pointing the finger at the City of Toronto for not salting the roads. But that’s not the case.

A multi-vehicle crash on the westbound Gardiner between Strachan Avenue and Dufferin Street left motorists stranded for hours as the highway was closed.

“I think the Gardiner received close to four rounds of salt prior to 8 o’clock in the morning,” said Hector Moreno, Manager, Road Operations with the City of Toronto Transportation Services.

But the frigid temperatures — which reached close to -22 C overnight — may have made the salt ineffective.

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“Salt loses its effectiveness when then ambient temperature is -13 to -15 C,” said Moreno.

“During conditions like today, we still continue to use rock salt; not so much as a melting product, but rather to provide traction for motorists, especially on hills, bridges, intersections, ramps or elevated structures like the Gardiner Expressway.”

Bridges or elevated structures such as the Gardiner tend to be colder than the ambient temperature due to air from above and below. There is no insulation from the ground, as with typical roads.

As for the spray that the city uses, it’s not effective in these temperatures either.

“In this particular case, unfortunately that only works effectively between -7 or -9 degree temperature. Anything above that you run the risk of refreezing,” Moreno said. “So instead of helping the situation, you’ve created an ice rink.”

This morning’s temperatures may have caused a chemical reaction on the Gardiner much in the same way the brine would: the sun warmed up the asphalt, then with some wind, it refroze.

Moreno stressed that drivers are aware of the road conditions.

“The key message we want to get out there is basically, look, motorists should be reminded to drive with caution and always be aware of the changing conditions, especially on the roadways, overpasses, bridge decks, ramps and elevated road structures.”

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BELOW: The full Skytracker weather forecast for Toronto and the GTA for January 3rd, 2014