I got waived off I-93 by State troopers in Concord, NH, in the early 80s. When we stopped at a store in Concord we overheard two guys talking about three or four accidents on city streets, one of which we later passed. The reason we’d been waived off the road was because a mile ahead there was a 27-car pile up. The roads were all iced, and you wouldn’t know it unless you tried to brake.
I was involved in a 30-plus car affair along those lines. It was just before Christmas, maybe 20 years ago, on a long, sweeping curve in southern Indiana, on I-64. Good visibility. You came around the curve and immediately saw a massive pileup about a half miles ahead. Naturally you started to brake. Instantly you slid. Foot off the gas, I braked, skidded, recovered, and braked again ... three times, and was finally rolling to slow stop at maybe five miles an hour as I finally came up on the wreck. Braked again, skidded again, and decided to go off the road below the wreck. Would have made it too, except some fool sailed into the mess ahead and above me, hit, spun around, and was gunning his engine and spinning his wheels wildly in a panic. He slid right into me, and all I could do was decide where on the front bumper to take the hit.
Moral of the story: there is such a thing as ice on which you cannot stop, until you roll to a dead stop.