Road still icy? Here's when it becomes too cold for salt to work

Road salt becomes less effective in colder temperatures, which is why freshly salted roads can stay icy in a hard freeze. Below about 15 degrees Fahrenheit, road salt’s effectiveness drastically drops, so switching to calcium chloride or magnesium chloride may be a better solution to icy roads. Here’s the science behind the glaze and what it means for your drive.