NPR this morning was reporting that one of the probable contributing factors in the collapse was the lack of any support colums beneath the bridge. During the design phase they decided support columns would get in the way of the large amount of barge traffic so didn't place any.

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I was just sitting here contemplating the immortal words of Socrates who said, "I drank what?"

"Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot." --Carl Sagan "Pale Blue Dot"