I wonder if its due to the roadwork they were doing on the bridge? Maybe someone playing with a jackhammer hit the right spot or something?
Well typically with this type of disaster, there are multiple small problems that, while by themselves pose no particular danger, together create a situation that couldn't possibly be predicted.
There were stress fractures around the tab welds that have been documented since the bridge was new.
The bearings showed corrosion and were repaired a number of years ago. Also, the workers that were currently resurfacing the deck were also doing repairs to a few joints. However, the crews were not actually doing anything at the time of colapse because of a shift change.
It was very hot in the middle of the day, and large bridges expand quite a bit on hot sunny days. (the reason for the bearings)
The low profile style of pier supports in the water have been known to, on other bridges, be undermined and weakened by long-term exposure to fast moving water.
I would have to say that a combination of all these things came together to cause this tradegy.
No doubt there will be an "Engineering Disasters" show on the history channel.
