Nearly 60 defendants went on trial in Genoa on Thursday, accused of manslaughter and undermining transport safety over the collapse of a bridge in the Italian city that killed 43 people four years ago.

The Morandi bridge, part of a key highway connecting France and Italy, gave way in torrential rain on August 14, 2018, sending dozens of vehicles and their passengers tumbling into the abyss.

The tragedy highlighted the state of Italy's transport infrastructure. Autostrade per l'Italia (ASPI), which runs almost half of the country's motorway network, is accused of failing to maintain the bridge that was inaugurated in 1967.

The tragedy shone a spotlight on the state of Italy's transport infrastructure
The tragedy shone a spotlight on the state of Italy's transport infrastructure AFP / ANDREA LEONI

"It's a very important day for families of the victims, but also for the entire country," said Egle Possetti, who heads a committee of relatives of the victims.

"We are confident in the fact that the trial will undercover the whole truth of this tragedy to avoid our loved ones dying in vain," she told AFP outside the court in Genoa.

One of the prosecutors, Walter Cotugno, has said "the Morandi bridge was a time bomb".

The tragedy shone a spotlight on the state of Italy's transport infrastructure
The tragedy shone a spotlight on the state of Italy's transport infrastructure AFP / ANDREA LEONI

"You could hear the ticking, but you didn't know when it was going to explode," he said in February.

Cotugno is convinced that the directors of Autostrade and the engineering company Spea, in charge of maintenance, "were aware of the risk of collapse", but remained reluctant to finance work in order to "preserve the dividends" of shareholders.

Most of the 59 defendants summoned by the Genoa court are executives and technicians of the two companies.

Family members of victims gathered outside the Genoa courthouse
Family members of victims gathered outside the Genoa courthouse AFP / Piero CRUCIATTI

They include the general manager of Autostrade at the time, Giovanni Castellucci, the former head of Spea, Antonino Galata, and officials of the infrastructure ministry.

While Castellucci's lawyers believe that the indictment "will fall like an autumn leaf", the prosecution counts on its key witness, Roberto Tomasi, Castellucci's successor and a high-ranking Autostrade executive since 2015.

At the time of the tragedy, Autostrade belonged to the Atlantia group, controlled by the wealthy Benetton family. Put under pressure by the political class and popular indignation, the family gave up its stake to the state last May.

"The bridge collapsed because of a hidden building defect, that's why 40 people died. Mr Castellucci has no criminal responsibility," said one of his lawyers, Giovanni Paolo Accinni.

For Raffaele Caruso, lawyer for the committee of relatives of the Morandi bridge's victims, this agreement "constitutes a first recognition of responsibility" on the part of the two companies.

"This is one of the most important trials in the recent history of Italy," he told AFP.

"In terms of the number of defendants, the scale of the tragedy and in terms of the wound inflicted on a whole city."