Just because hindsight is 20/20, would they have been better off to cut the beams of the bridge loose, blast them off like they do when they demo a steel bridge? If the steel had been gone, they could have probably saved the pilings, then to fix it, all they would have needed was new bridge girders.
Probably hard to set up in a crisis situation, call the army and have them do it as a "training exercise". Plus that's a pretty gutsy call to make, "blow the bridge", not likely to happen in a corporate structure, no one willing to make a decision like that.
I think with the steel gone, they might have saved the rest, now its a job to rebuild.