A strategic infrastructure that allowed Northern Italy and Southern France to be connected, but that most of all was the main road axis for the city of Genoa. Let's go through the historical events of Genoa's Morandi Bridge: from its first conception, to when it collapsed, on August 14, 2018, when a section of the viaduct gave way, together with the supporting pillar no.9.
The Polcevera Viaduct was designed by the engineer Riccardo Morandi. It was built between 1963 and 1967, the year of its inauguration, which was attended by Italy's President, at that time, Giuseppe Saragat.
The bridge that crossed the Polcevera river, between the Sampierdarena and Cornigliano neighbourhoods, measured 1,182 metres in length; its major span measured 210 metres, with 90-metre long piers. The viaduct, built to connect the new A10 motorway to the A7, spanned across a railway network, a housing agglomerate and various industries.
The Morandi bridge was an engineering structure that shone for the technical solutions that were used to build it, and for its beauty: a structure with two main spans, supported by three piers, and reinforced concrete tie beams, followed by minor spans.
The story of the Morandi bridge began between the end of the 50's and the beginning of the 60's. In the same period, the same Italian engineer designed the twin bridges built in Venezuela and Libya. This bridge was a stayed-cable one: it was suspended. The deck was supported by cables (hence the name cable-stayed) - made with prestressed reinforced concrete and anchored to supporting posts.
The distinctive feature of the Morandi bridge, besides being built using patented material especially created by the designer, was the use of stays, which are normally made just with steel. In this case, they were made with steel, but also covered with prestressed concrete. This material is generally used to work under stress, to meet the pressure of convergent forces. This was something new that Mr Morandi introduced when he built the Maracaibo Bridge in Venezuela, also an unfortunate story to remember. In fact part of the General Rafael Urdaneta bridge collapsed in 1964, due to a violent collision of the Exxon Maracaibo oil-tanker, which hit piers 30 and 31. The collapse caused three of the bridge's spans to be taken to sea.
August 14, 2018, 11:36 a.m.: A huge rumble broke Genoa's silence. Ceaseless rain poured down on the city, that day. A section of the Polcevera Viaduct - known as the Morandi Bridge - collapsed, causing 43 victims.
The cause was structural: some parts of the viaduct just did not resist. The collapse of Genoa's Morandi Bridge concerned a 150 metre-long section, due to which, in addition to the 43 victims, 566 people also lost their homes.
Once the emergency situation had been declared, inquiries and investigations to understand, clarify and ascertain the reasons that brought to this tragic event, immediately began.
For the Genoese, the Morandi Bridge was their "Brooklyn Bridge": It appeared solid and majestic. Despite this, during the 80's, new stays were added to the bridge, to increase its solidity. This was necessary, as the viaduct was inelastic, according to tests done at that time.
Discussions regarding whether to close the bridge, to renovate it and make it safer, were carried out many times. Still, the bridge remained open to traffic, and only went through periodical maintenance, the last of which was carried out in 2016.
Until, one day, the city of Genoa had to witness the collapse of the Morandi Bridge with “its own eyes”.
Many said that what happened was a tragedy that could have been avoided.
Many experts were immediately questioned, after the bridge's collapse. One of the main perplexities concerned the stability and durability of the Morandi Bridge, and therefore its fast and premature deterioration. The construction technique used to build the bridge, based on the Brevetto M5 patent, in retrospect, scored a negative result. Attempts to preserve and strengthen the structure, just after 20 years since its construction, showed a corrosion-phenomena trend. Moreover, since 1990, the bridge has been put through constant maintenance. This, on one side, demonstrated that the bridge was constantly monitored; on the other, though, it showed that it was going through a period of deterioration, due to its "failures". In spite of this, these conditions never defined the bridge as dangerous, nor a need for it to close.
Its collapse, according to inquirers, was “caused by the corrosion of the internal cables, but the reasons of the actual collapse”, they said, “will be provided by the technical experts”. They found that what, initially, collapsed, was the South-Eastern stay. The deck went down in just one and a half seconds, bringing all the vehicles that were crossing the deck, in that moment, also down with it.
The inquiries of Genoa's Public Prosecutor's Office, to ascertain the reasons for the collapse, and the works carried out by the technical experts, are still underway.
The companies appointed to build the new bridge are Salini Impregilo, Fincantieri and Italferr, which gave way to the creation of the new company "PerGenova". The project's design was signed by Archistar Renzo Piano, whose idea was to build a structure resembling a ship's keel.
Fewer piers for the new structure: 10, against the previous 18 foreseen by the project of Renzo Piano. Building 18 piers instead of 10 guarantees greater safety, but longer times and possible complications.
Lights are also pointing towards the project’s anti-corrosion systems. Corrosion, in fact, is a phenomenon caused by the bridge's closeness to the sea, which according to the technical expert reports, could have been the actual cause for the collapse. This is why the decks of the new viaducts will also include internal air-conditioning and dehumidifying systems.