Report: Experts knew Genoa bridge had weakened 20 per cent months before it collapsed

GENOA, Italy—Engineering experts determined in February that corrosion of the metal cables supporting the Genoa highway bridge had reduced the bridge’s strength by 20 per cent — a finding that came months before it collapsed, Italian media reported Aug. 20.

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.

In its report, news magazine Espresso cited the minutes of a meeting of the Genoa public works superintendent, which included Roberto Ferrazza, an architect named to head a government commission looking into the disaster, and Antonio Brencich, an engineer who has been outspoken about the bridge’s flaws.

In the Feb. 1 meeting, Ferrazza recommended that the supports be reinforced given the “trend of degradation” being registered. Bidding on a 20-million-euro contract to reinforce two of the major supports for the bridge, including one that collapsed, was scheduled to close next month.

Prosecutors investigating the bridge’s collapse have said, among other things, they are looking at possible faulty maintenance or design flaws.

Prosecutor Francesco Cozzi said Monday they are also looking for any possible weakness in oversight. He said he could not say yet whether the presence of a movable maintenance platform weighing several tons on the bridge’s underside contributed to the collapse.

He repeated that the investigation will take time but said “certainly it will be done in a reasonable time frame.”

Ferrazza said the preliminary survey suggested a series of possible causes and not just a simple collapse of the bridge support since the span appears to have initially experienced a distortion.

“We have to look at the positioning of the rubble, considering that there was a break that provoked an imbalanced movement of the structure,” the ANSA news agency quoted Ferrazza as saying.

Espresso reporter Fabrizio Gatti told SKY TG24 that a 20 per cent reduction in strength would not be significant in a modern bridge, but on a structure with the known defects of the Morandi Bridge it should have merited swifter, more decisive action.

“Everyone was well aware of the situation on that bridge,” Gatti said.

The Italian engineer who designed the bridge warned four decades ago that it would require constant maintenance to remove rust given the effects of corrosion from sea air and pollution on the concrete.

RAI state television broadcast excerpts of the report that the late engineer Riccardo Morandi penned in 1979, 12 years after the bridge bearing his name was inaugurated in Genoa. The Associated Press downloaded the English-language report from an engineering news portal.

At the time of writing, Morandi said there was already a “well-known loss of superficial chemical resistance of the concrete” because of sea air and pollution from a nearby steel plant. He said he chose to write about it because the degradation represented a particular “perplexity” given the “aggressivity” of the corrosion that wasn’t seen in similar structures in different environments.

Morandi reaffirmed the soundness of the reinforced concrete bridge design he used but warned: “Sooner or later, maybe in a few years, it will be necessary to resort to a treatment consisting of the removal of all traces of rust on the exposure of the reinforcements, to fill in the patches.”

He recommended using an epoxy resin to cover the reinforcements with materials “of a very high chemical resistance.”

The Italian government, meanwhile, appears divided on how to proceed in relation to Autostrade per l’Italia, the company that operated the section of highway that collapsed.

Autostrade per l’Italia’s board approved on Aug. 21 an initial 500 million euros in funding to help victims and finance a new steel bridge that it says can be ready in about eight months.

Premier Giuseppe Conte says procedures have begun to revoke the company’s concession to operate some 3,000 kilometres (nearly 1,900 miles) of Italian highways, about half of the total highways operated by private companies.

Italy’s main union confederation estimates it would cost Italy between 15 billion and 18 billion euros to revoke the highway rights.

With files from Nicole Winfield of The Associated Press