Never have quite figured out how these pile-ups occur. Do people really think it'll be fine to go barreling through a sand storm or fog bank at highway speed? Is it not common sense to slow down or come to a stop in such a situation? I realize the first people who got there probably did that, and that's what caused the people behind them to crash. But why didn't those people behind them think, "Oh look, I can clearly see a giant sand storm blowing across the road 5 miles ahead of me and I bet the people who are there now may be stopped so I should probably slow down."