The bridge collapse on Tuesday will bring intense scrutiny to that infrastructure legacy. In the interview with RAI, Toninelli said that older structures would be prioritized.
The Morandi Bridge, or the Polcevera viaduct, opened to the public in 1967 after four years of construction. It carries travelers from the northern parts of Lombardy to the beaches of Liguria, cutting through the middle of of the industrial port city of Genoa to connect two major highways in the area, the A10 and the A7. The bridge’s size and height is visibly daunting. Stretching 3,615 feet, it towers some 148 feet over roads, railroad tracks, and the Torrente Polcevera, a slim stream.
The bridge’s construction used a mix of both reinforced and prestressed concrete, a technique that the bridge’s namesake, the engineer Riccardo Morandi, was known for; he built similar projects in Venezuela and Libya. But its striking design, while celebrated, proved increasingly expensive to keep up since the 1980s—a point that Brencich had alluded to years before, saying that the combination of the two different types made the structure uneven.
However, Italian authorities said on Tuesday that the bridge was inspected regularly, and its foundation was being restored at the time of the collapse. A restructuring project had also been funded in 2016.
With an official investigation into the cause of the collapse just beginning, both local and federal officials mentioned that a criminal inquiry would be opened into whether negligence was involved. Witnesses at the scene described serious storm conditions, and told reporters that lightning was seen in the area at the time of collapse. According to AccuWeather, the wind was gusting up to 30 to 40 miles per hour.
That may or may not have been a factor in the collapse. Wesley Cook, a structural engineer at the New Mexico Institute of Mining and Technology, told CityLab that he couldn’t comment on the specifics of the situation in Genoa. “In a historical context, before 1950, wind was the number-one reason bridges collapsed,” he said. “That has shifted, though, through research and reporting.”
With decades-old structures, Cook said that regular maintenance is more critical than age itself: The condition of bridges built decades ago can swing between “good” and “poor.” Public agencies, he said, will try to keep it at that threshold, and not let it get any worse. (With the Minneapolis I-35W collapse in 2007, which killed 13 people, the National Transportation Safety Board ruled age out as a key factor. Investigators traced the failure of that 40-year-old bridge to a design flaw.) “Usually there’s a triggering event that causes the collapse,” Cook said. “It doesn’t matter if it’s 40 years old or 140 years old, once you get out past 25 years.”
Cook, who authored a 2014 study on bridge failures nationwide, said that “many but not all” suspension bridges were more vulnerable than other bridge types. What really matters, he added, is whether or not the bridge is deemed “fracture critical”—these are defined as structures in which, among other things, the failure of a single element will bring on a catastrophic cascade. As in the recent pedestrian bridge failure in Miami and the I-35W disaster in Minneapolis, deadly collapses, Cook said, are often the culmination of multiple causes.
Two years ago, Genoese engineer Brencich made a similar point: “The collapse of a bridge,” he said, “is the result of a long series of errors.”
This piece appears courtesy of CityLab.