I am in the Steel design and construction business. And I can tell you that the various loads that you mentioned, are the very ones that are always taken in consideration when designing a bridge. In fact, in steel construction, there is so much over designing that goes on, that it really takes something unforseen to bring a structure down (eg. earthquake, barge hit, etc.) Im not saying that it could not be a design failure but that is usually not the case. Also, a fourty year old bridge is not that old. But I am sure the various engineers of record will pour over the design dwgs, to see where the failure might have occured. Also if this bridge was under construction, you can be that before the project took place, a team of civil engineers were all over it to make sure it could structurally take the construction project.
2006 inspection reported minor structural fatigue on the main beams. Per Channel 5.
absolutely ...
but either mistakes in design OR improper construction OR improper materials OR unaccounted corrosion/lack of proper maintenance can lead to a failure.
My guess would be improper materials or corrosion/lack of maintenance.
In the 1980’s (early) - a 30 - 40 year old bridge span in Connecticut, part of I-95, fell into a river - and IIRC - it was poor maintenance (or marginal design combined with poor maintenance) that lead to the failure.
Mike, PE
All of your comments were interesting and helpful. What you said below does make me wonder now about a possible cause:
“Also if this bridge was under construction, you can be that before the project took place, a team of civil engineers were all over it to make sure it could structurally take the construction project.”
Usually, it’s not one single thing. As I said, the larger than normal weight plus metal fatigue plus corrosion. Any way just a guess.
what about 2 closed lanes and more load on the 2 open lanes? Could there have been a tipping event with the metal like with a ship listing due to uneven weight distribution?