The collapsed Italian motorway bridge which killed at least 22 people was undergoing foundation strengthening works at the time it collapsed.
Italian highways operator Autostrade has confirmed that it had been carrying out maintenance work on the flyover bridge when what is understood to be a 250m length and pier collapsed.
The operator said it had been strengthening the structure’s foundations as part of scheduled maintenance works, although it is not yet clear where foundation work was taking place.
“The works and state of the viaduct were under constant monitoring and supervision,” the company said in a statement. “The causes of the collapse will be thoroughly investigated as soon it is be safe to access the site.”
Deputy transport secretary Edoardo Rixi confirmed that at least 22 people have died in the collapse, with a further eight people taken to hospital with various injuries.
The bridge has been subject to numerous maintenance projects since the last 1980s, most recently in 2016.
Inaugurated in 1967, the bridge – nicknamed the Brooklyn Bridge by locals – has undergone several renovations since the 1980s, including a project to add new steel cables to strengthen the structure in the 1990s.
The way in which the tower collapsed has left engineers “shocked”.
Independent bridge consultant Simon Bourne said: “What shocked me is that the whole tower has gone. It’s not just a piece of the deck which has gone which normally happens, it’s the whole deck. That’s very unusual.
“What on earth could cause the whole tower to come down? The entirety of one side must have gone.
“The tower, which is generally designed to be in balance structure, but with one side gone, that would then cause the whole tower to rotate and fall over quite quickly.
“It could have been a lightning bolt, it seems pretty unlikely, but there’s a potential it could have hit the top anchor point and had a massive impact on it.”
He added: “One trait of the early bridges is that they had a single batch of big cable stays. Today’s cable stayed bridges have a whole fan array of cable stays which are easier to construct, gives more robustness in case one fails and are easier to replace if needs be.”
The 11 span, pre-stressed concrete, cable stayed bridge is similar to two other bridges in Venezuela and Libya also designed by Riccardo Morandi.
First designed in 1957, construction of the Genoa bridge was carried out between 1963 and 1966.
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