There will be structural engineers around the world scratching their heads today and feeling worried about their own bridges of similar design. I worked for a structural consultancy when the World Trade Centre came down and although the design process had moved on since then, hundreds of other buildings in the 70's and 80's had been based on that design. Of course it had never been envisage that it would be hit by a huge jet plane, but the limitations were known and even in 2011 buildings were already being designed to take a direct hit by a loaded 747 but nobody was going to pull down a couple of billon $ buildings on the off chance that some nut would fly a big 'plane into it. Of course we know better now, but there must be a huge number of high rise buildings in the US and elsewhere built to that design. It is natural that if a design is economic and successful, other engineers are going to copy it, so there will be bridges all over the world today being subjected to intense scrutiny.
Some say that the failure was predicted 2 years ago due to poor maintenance and Italian politicians are already queueing up to blame the EU because the promised funds to enable the works have not materialised. I think the joke about Mafia concrete may not be far from the truth. I have been involved in inquiries in the Middle East where local concrete has been so substandard that it was little better than mud and whole buildings had to be torn down after our engineers had refused safety certificates even though the strength was apparently up to standards when test cubes were evaluated locally.
Mike.X