I talked about what I thought happened to cause the Minneapolis bridge to fail in my last dairy, Aug 02, 2007 "Bridge a Bad Sign of Modern Reporting",and it looks like the off center loading of the bridge was a major cause. The question is what lessons should be learned for the future from this disaster?
The first easy lesson I can think of is to never allow another deficient bridge to be repaired while in use.
The people working on the bridge in Minneapolis were road repair people not bridge engineers. We don't even know if an engineer planned the repairs to the bridge or if they were planned by the "do the worst stuff first method". It really doesn't matter who planned the repair work schedule, because nobody could have planned for all the loading that took place just before the bridge fell.
The best argument for not allowing the public on another bridge under repair is humanitarian. It's very sad to see two young women realize they've lost their mother and that should be enough to make it worthwhile for the County, State and City planners to think about the next lesson.
Lesson two is plan now how to re-route traffic for the next bridge repair. It would be a lot better to build some wider lanes and a couple of temporary on or off ramps in advance of a bridge repair and shut down the bridge than to hope the bridge now being repaired doesn't fall and be unlucky. Then you've still got to re-route the traffic but this time with people yelling at you. In light of all that's happened in Minneapolis I don't think the public would want a government planner to stay in his job if it happened again.
Lesson three is money. I think the cost of one bridge failure like this would easily be more than the modest cost a planned re-routing would take from the budget, and if this type of failure and loss of life happens again with any of the similar bridges surely the courts will teach government lesson three better than anyone else.
I believe lesson four should be learned by the insurance company that allowed an active bridge to be repaired by one of their contractors. I'm not talking about just money, I'm talking about criminal penalties that I think should be handed out if another bridge is repaired while the public is on it and loss of life occurs. If no insurance company can cover the liability of repair of an active bridge the practice will end.
One way or the other repair on an active bridge must be dealt with. Cutting holes in a bridge deck while the Westbound lane is loaded in a cantilever fashion, bridge members going from compression into tension in ways that have rarely happened there before, men working as fast as possible but not knowing they are working beyond their ability; the public should not have been there.