If you recall the 2019 bridge collapse in Genoa Italy, and wondered what the cause was and if it was investigated and discovered, well, so did I. So I looked into it

The authorities in Genoa handed down warrants for the arrest of several top managers at the company tasked with overseeing a bridge that collapsed in the city in 2018 killing 43 people, the clearest attempt yet to hold the company’s leadership accountable for the tragedy.

Prosecutors issued warrants for the former chief executive officer and other officials at the motorway operator, Autostrade per l’Italia, which managed the Morandi Bridge, in an investigation into highway neglect.

Giovanni Castellucci, the forme chief executive of Atlantia, of which Autostrade per l’Italia is a subsidiary, Michele Donferri Mitelli, the former general director of maintenance for the company, and Paolo Berti, its chief operations and maintenance officer, were all placed under house arrest.

Investigators found “grave criminal conduct, linked to entrepreneurial policies aimed at maximizing profits deriving from the contract with the state, through the reduction and the delay of the expenses needed to maintain the motorways, at the expense of public safety,” the judge who ordered the arrest warrants wrote in a court document
 

The bridge — which spanned more than a half a mile over a riverbed, residential buildings and warehouses, connecting western and eastern Genoa — abruptly collapsed one foggy morning in the summer of 2018

Morandi Bridge construction resulted in cables were difficult to inspect, and it was unclear how they were coping with increased traffic loads since the opening of the bridge in 1967

“When I visited the bridge in the early 1990s for a documentary on Morandi’s work, I was [surprised] to see fissures and corrosion just 20 years after its completion,” says Giuseppe Imbesi, an architect who worked with Morandi on a bridge proposal for the Strait of Messina.

Morandi himself was surprised to see the structure age faster than he had anticipated. In 1979 he issued a report detailing a number of interventions to protect the structure against pollution from nearby factories and the salty sea air.

Little, however, was done, and by 1992 the trademark concrete cables were heavily corroded.
 

The deck was entirely made of reinforced concrete, and it had only four cables per tower, instead of the usual dozens. Crucially, the cables were covered in pre-stressed concrete – a type of treated concrete invented by the French engineer Eugène Freyssinet. Unlike normal reinforced concrete, which is generally best suited to resisting compression, the new pre-stressed concrete was specifically designed to resist traction.

As a result, Morandi Bridge was stronger and lighter, with minimal use of steel, than any other bridge of its era – and boasted a clean, distinct design that quickly became a symbol of Italian engineering, tangible proof of the country’s technical abilities.

“The bridge’s concrete structure won’t need any maintenance,” boasted an article in La Stampa newspaper ahead of the bridge’s opening. “Neither will its stayed cables, which are protected from atmospheric agents by their concrete vest.”

The material was perfectly suited to postwar Italy. The country couldn’t afford the amount of steel necessary to build something like the Brooklyn Bridge: steel was in short supply because of international sanctions that had been placed against the fascist government, and Italy lacked the resources to produce steel domestically. It was, however, rich in the clays and river sediments necessary for concrete production. Led by Morandi, the country’s engineers learned how to achieve the same results with concrete that they would with steel.

In a document on the probe's findings seen by Reuters, prosecutors said the collapse was triggered by the rupture of the load-bearing cables inside the stay of the bridge's ninth pillar, which were eaten away by a highly corrosive atmosphere over the 51 years of the bridge's life.

Managers at Atlantia units Autostrade per l'Italia and SPEA allegedly avoided proper checks of the state of the infrastructure and did not correct serious issues that started to emerge only a few years after the viaduct opened in 1967, the document showed.

https://en.wikipedia.org/wiki/Ponte_Morandi

https://www.nytimes.com/2020/11/11/world/europe/autostrade-arrests-genoa-bridge-collapse.html
https://www.theguardian.com/cities/2019/feb/26/what-caused-the-genoa-morandi-bridge-collapse-and-the-end-of-an-italian-national-myth
https://www.reuters.com/world/europe/italian-prosecutors-prepare-possible-charges-after-concluding-genoa-bridge-probe-2021-04-22/
https://justacarguy.blogspot.com/2018/08/22-dead-as-result-of-morandi-main.html