Ponte Morandi ( Morandi Bridge)

Ponte Morandi (English: Morandi Bridge) was a part of the Polcevera viaduct, on the A10 motorway in Italy. It crossed the Polcevera stream between the districts of Sampierdarenaand Cornigliano in Genoa. The viaduct was built between 1963 and 1967, and opened on 4 September 1967; it was named after its designer, Riccardo Morandi. The bridge partially collapsed on 14 August 2018, killing at least 39 people (with another 3 missing).

History

Design

The bridge was designed by Riccardo Morandi. It is similar to his earlier 1957 design for the General Rafael Urdaneta Bridge, located at the outlet of Lake Maracaibo in western Venezuela, and connecting Maracaibo with the rest of the country, which also partially collapsed in 1964 when the tanker Esso Maracaibo collided with the approach spans. Morandi's cable-stayed bridges are characterised by very few stays, often as few as two per span, and often with the stays constructed from prestressed concrete rather than the more usual steel cables.

Construction

The viaduct was built between 1963 and 1967 by Società Italiana per Condotte d’Acqua (it). It had a length of 1,102 metres (3,615 ft), a height of 45 metres (148 ft) at road level, and three reinforced concrete piers reaching 90 metres (300 ft) in height; the maximum span was 210 metres (690 ft). It featured a cable-stayed bridge, where the vertical elements are trestlesmade up of two superimposed Vs: one carried the roadway beam, while the other, upside down, supported the upper tie rods.

The viaduct was officially opened on 4 September 1967 in the presence of the President of the Republic Giuseppe Saragat.

Maintenance and strengthening

The bridge has been subject to almost continual restoration work since the 1970s due to an incorrect assessment of the effects of viscosity of the concrete in the bridge's design. This oversight resulted in excessive deferred displacement of the vehicle deck[3] so that it was neither level nor horizontal; at the worst points, it undulated in all three dimensions. Only after continual measurement, redesign, and associated structural works was the vehicle deck considered acceptable, approaching horizontal by the mid-1980s.

Redesign and structural changes continued. From 1990 onward, the easternmost pillar had its stays strengthened by flanking them with external steel cables. The original stays were kept in place, their pre-stress effect having been only modest.

On 3 May 2018, the Autostrade Company announced a call for tenders for the structural upgrade of the viaduct to the value of €20,159,000, with a deadline of 11 June 2018.

Workers were installing brand new heavy Jersey barriers on the Ponte Morandi before it collapsed.

Replacement proposals

By the mid-2000s, the A10 route through Genoa and over the bridge had become highly congested. The City council requested proposals for improvement of traffic flow through Genoa, with the Autostrade Company in 2009 resultantly proposing the "Gronda di Ponente" project to improve flow, by moving traffic to a new-build Autostrada interchange system located to the north of the city. As part of the initial study and report, the Autostrade Company measured that the bridge carried 25.5 million transits a year, with traffic having quadrupled in the previous 30 years and "destined to grow, even in the absence of intervention, of a further 30% in the next 30 years". The study highlighted how the traffic volume, with daily queues at peak hours joining the Autostrada Serravalle, produced "an intense degradation of the bridge structure subjected to considerable stress", with the need for continuous maintenance. The study showed that in the option for improving what was termed as the "low gutter", it would be more economic to replace the bridge with a new structure located to the north of its current location, and subsequently to demolish it on the opening of the new replacement route.

In 2016, the bridge was characterised by Antonio Brencich, a Professor of Structural Engineering at the University of Genoa, as a "failure of engineering", mainly due to high maintenance costs.

Collapse

A 210-metre (690 ft) section of the Ponte Morandi collapsed on 14 August 2018 at around 11:30 local time (9:30 UTC) during a torrential rain storm, centred on the westernmost pillar and crossing the Polcevera stream and an industrial area of ​​Sampierdarena. Eyewitnesses reported that the bridge was struck by lightning before it collapsed. Between 30 and 35 cars and three trucks were reported to have fallen from the bridge.

The initial hypotheses are that a structural weakness or a landslide caused the collapse.[17][18] A large part of the collapsed bridge and the vehicles on it fell into the flooded Polcevera stream. Other parts landed on the tracks of the Turin–Genoa and Milan–Genoa railways, and on warehouses belonging to Ansaldo Energia, an Italian energy company, which were largely empty because the collapse occurred on the eve of Ferragosto. The bridge was reportedly undergoing maintenance at the time of the collapse, including strengthening the road foundations.

Victims and rescue efforts

39 people were confirmed dead, fifteen were injured, and others are still missing. Among the fatalities were three Italian children, three Chilean citizens, two Albanians, and three French, while others are Italians under the age of 50. The identities of the majority of the victims have yet to be released.

Multiple survivors were transported to nearby hospitals, many in critical condition. A Czech truck driver survived the fall with a broken nose, four broken ribs, and a punctured lung. Davide Capello, former goalkeeper for Cagliari, survived without injury and was able to walk away from his car, even though it dropped 30 metres (98 ft) before becoming wedged between parts of the fallen bridge.

The area under the remaining part of the bridge, including several homes, was evacuated. As of 02:00 the following day (midnight UTC), twelve people were known to be still missing, some of whom could be heard calling from underneath the debris, and rescue efforts were continuing by floodlight using techniques commonly deployed after earthquakes.

Aftermath

Governor Giovanni Toti said that the loss of the bridge was an "incident of vast proportions on a vital arterial road, not just for Genoa, but for the whole country".] According to Deputy Minister of Infrastructure Edoardo Rixi, the entire bridge will be demolished. The disaster resulted in a drop in the stock price of the road's operator Atlantia, whose stock price dropped up to 11% and closed slightly below 5% for the day.