Bridge Collapse

[xoxoxoBruce]

When glare ice coats the highways, sand and salt trucks roar to the rescue, saving thousands of drivers from injury or death. The quantity of salt applied to Minnesota roads increases each year, up to 320,000 tons in 1999.

Calcium chloride and magnesium chloride
Novotny et al. (1999) provide a comprehensive overview of calcium chloride and magnesium chloride. These chemicals are more costly than many other deicers, but work at lower temps and have a faster melting capability. Both are commonly used with rock salt when temperatures fall as low as -25 degrees C. Calcium chloride is more corrosive than rock salt so it is seldom used alone.
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Calcium Magnesium Acetate (CMA)
CMA has received much attention in the literature as potentially the best alternative to deicing salt because it is not corrosive and causes less damage to plants, soil, and organisms.
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A strong deterrent to widespread CMA use is its high cost. It typically costs $600 per ton, compared to $30/ton for salt.

[tw]

Originally Posted by xoxoxoBruce

I believe UT may be refering to a problem with bridges in MN. Their surface tends to be colder and tends to freeze faster. Salt that may work on MN roads may not be sufficient to keep bridges from freezing. Therefore bridges with heavy traffic may suffer from more of more destructive deicing materials. But again, only wild speculation because we don't even know bridge condition previous to collapse and don't know how the collapse occurred - even where the failure started.

For example, did the foundation at one end of the bridge shift causing one truss to slip off? I have very little information here. And I don't see many answers appearing in reply to numerous questions.