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Engineering Experts Knew Italian Bridge Had Corrosion Problems Before It Collapsed, Report Says (apnews.com)

Posted by msmash on from the closer-look dept.

McGruber shares a report: Engineering experts determined in February that corrosion of the metal cables supporting the Genoa highway bridge had reduced the bridge's strength by 20 percent -- a finding that came months before it collapsed last week, Italian media reported Monday. Despite the findings, newsmagazine Espresso wrote that "neither the ministry, nor the highway company, ever considered it necessary to limit traffic, divert heavy trucks, reduce the roadway from two to one lanes or reduce the speed" of vehicles on the key artery for the northern port city. A large section of the Morandi Bridge collapsed Aug. 14 during a heavy downpour, killing 43 people and forcing the evacuation of more than 600 people living in apartment buildings beneath another section of the bridge.

6 of 141 comments (clear)

  1. The other mistake by SuperKendall · · Score: 3, Interesting

    If corrosion weekend the cables by 20% of so, it seems like the original design didn't leave nearly enough margin for error!

    I imagine they were not as concerned with 20% weakening thinking they had much more leeway.

    --
    "There is more worth loving than we have strength to love." - Brian Jay Stanley
    1. Re:The other mistake by fredgiblet · · Score: 3, Interesting

      Read the wiki article on the bridge. They've been fighting it's design for it's entire life and were even starting to prepare a replacement.

    2. Re:The other mistake by Thelasko · · Score: 4, Interesting

      AvE posted a great video on this bridge. The designer of the bridge didn't like adding extra reinforcing. This was probably for aesthetics. This made maintenance of the bridge difficult as structural components couldn't be repaired while the bridge was in service.

      --
      One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
    3. Re:The other mistake by Anonymous Coward · · Score: 3, Interesting

      It's been a lot of years since engineering school, but I seem to recall the recommended safety margins for most things were 100%-500%, so yes, a 20% weakening causing collapse would be a symptom of serious under-engineering.

      IAAME (I Am An Mechanical Engineer). For civil engineering projects, a safety factor of 3 to 4 would be normal and more than likely would be documented

      However, Wikipedia says this bridge is 51 years old, and that engineers have been expressing concern over its safety since the early 90s, with numerous other static and dynamic weaknesses being uncovered over the years, due to both degradation, and weakness in available computer modeling in the 60s.

      Years after it was built, the DESIGNER of the bridge expressed concerns about its safety. Because of pollutants in the air, the weather pattern around the bridge, and the unique design of the bridge, he specifically said that corrosion on its parts was greater than he had observed in other bridges of this same design. HE warned that they really needed to watch this bridge closely for corrosion problems. And because of the lack of computer modeling, that normally causes good engineers (which I believe the bridge designer to have been) to over specify the safety factor. I think this is a clear case of the authorities not doing maintenance on a bridge that clearly needed extra maintenance and it just caught up to them. Gordon

  2. Corrosion problems on Forth Road Bridge in Scotlan by Pop69 · · Score: 3, Interesting

    When they identified corrosion problems with the main cables on this bridge, they installed dehumidifiers for the cables. They also built a replacement bridge and now use the older bridge as a public transport route, a traffic level it can easily cope with. Perhaps this should have been done with this bridge too ?

  3. Re:Bridge engineers always consider overload by Freischutz · · Score: 4, Interesting

    Itâ(TM)s not just that, the bridge was hopelessly overloaded by traffic.

    Have you ever driven in New York City? Every bridge is totally full of traffic nearly 24x7, during rush hour basically parked (it took me an hour once to cross George Washington bridge leaving NYC near rush hour). That happens every day, including in driving rainstorms... bridges are usually built assuming the bridge is packed with trucks, during the worst storm imaginable (including many feet of snow, far worse than rain), then use safety margins well beyond that. It seems the designers of this bridge cut some corners.

    I’ve driven in all kinds of places. However, the real question is: Have you ever observed the dysfunctional cocktail of corruption, populism and incompetence otherwise known as Italian politics at work? In this case you have a steadily deteriorating bridge whose load carrying capacity is rapidly decreasing, that may not have been built to specs in the first place due to corruption and that was being subjected to traffic loads and thereby vibrations that its decayed structure could not handle. And the whole time there is a political cat fight going on with a bunch of populists wingnuts who are blocking the replacement bypass project, staging protests against any repair work and ridiculing anybody who spoke out about the danger of the situation. The bottom line is that this bridge should have been replaced and decommissioned at least ten years ago.