My heart goes out to those affected by the tragic collapse of the I35W bridge in Minneapolis. And, for all of the rest of us, this is a scary thing. I remember the 1989 California Earthquake, when the Cyprus Structure collapsed. This was also close to the time of Rush Hour— which may have been a bit early as people were going home to watch the World Series game. Quite a number of people were killed there as the upper deck of the two-deck section of freeway collapsed on the lower deck. I know that visions of that haunted me for years; I'd been on the upper deck of that freeway that very morning, driving back down to college at the end of a fall break. (Ironically, I wasn't supposed to be; my sister and I cluelessly drove on the wrong freeway, and had to correct for it later.) It was only the next day when I realized that my Dad was in fact on that freeway heading north, and was just before the Cyprus Structure when it collapsed. His main workplace was in another direction, but he had been south of Oakland at a jobsite. He got off of the freeway to pick up a bottle of wine, and was there when the earthquake hit. (I related this to people in West Dorm, the famous party dorm, and they said, "See! It's good to drink, saves your life!")
My sincere hope is that rescue efforts in Minnesota will proceed as efficiently and as effectively as possible, that those who are missing will be found alive, and that the families of those who were injured or killed will find comfort.
When we're past that stage, I hope that we place a much greater emphasis on understanding what went wrong than we do on finding somebody to blame. When something like this happens, we all feel fear and shock and anger. It's so tempting to want to find a target of that anger— to find somebody whose fault it was. I suspect that in this case the fault will not be so obvious. And, in any event, understanding what went wrong is more important, so that hopefully we can figure out if there's anything we can do to stop similar things from happening in the future. One of the classic things we always talk about in introductory Physics classes is the Tacoma Narrows Bridge, which catastrophically collapsed in 1940. Because of that accident, we learned something about the various resonant modes that one must take into account when designing a bridge. Who knows if there will be anything as relatively straightforward as that with this collapse— but once the disaster recovery is over, I sure hope that we are able to place more emphasis on figuring out what happened, than deciding whom or what to blame.