I have a personal, scary situation as it related to a HUGE thick slab of heavy ice that flew off the top of a truck, going by me (I was on the sidewalk). No exaggeration -- that ice slab was a good 12 feet long and it crashed (Loudly!!) on the sidewalk, about a foot in front of me, where I was walking. Had that heavy ice come down on top of me, it would have knocked me to the concrete, and probably really injured me.
(This happened a few years ago, and I'll never forget it. I have zero tolerance for trucks not removing ice, before they go out on the road.)