The first span has been lifted into place for a new bridge to replace a viaduct that collapsed in August 2018 in Genoa, Italy.

A 50 meter long section weighing roughly 500 tons was lifted about 50 m above the ground by cranes that earlier had been used to dismantle the failed Morandi Bridge, whose collapse killed 43 people. Another 18 deck sections will be installed during the coming months.

Artist's rendering of the new span under construction in Genoa, Italy. Source: Renzo Piano studioThe new bridge over the Polcevera River will have a 1.1 km long continuous steel deck with 20 spans and 19 elliptical piers.

Pergenova, a joint venture of Salini Impregilo and Fincantieri Infrastructure, is building the $230 million bridge.

The bridge’s designer, Renzo Piano, also took part. The design incorporates weight-bearing columns that are said to resemble the bow of a ship. They will be illuminated by 43 lamps casting a light shaped like ships’ sails and representing each of the victims. Piano will also be the project’s technical supervisor.

The bridge crosses a densely populated area and is a key artery for much of northern Italy, including the port city of Genoa, the Ligurian coast and southern France.

Salini Impregilio's bridge-building experience includes a replacement of the Gerald Desmond Bridge in Long Beach, California, the Unionport Bridge in New York and a second bridge over the Bosphorus Strait.

Salini Impregilo and Fincantieri formed the new company to oversee the project.

2018 accident

The bridge that collapsed during a heavy storm in August 2018 carried the A10 motorway across a river, railroad tracks and numerous structures. It was built between 1963 and 1967 by the Italian Society for Water Pipelines and was designed by Italian engineer Riccardo Morandi. At the time of the collapse, the bridge was being repaired. The Italian transport minister said that the bridge, known as the Polcevera viaduct, had shown signs of problems in the past.

The viaduct that failed had a length of 1,102 m (3,615 ft), a height of 45 m (148 ft) on the road level and three reinforced concrete piers that rose 90 m (300 ft) in height. The maximum span was 210 m (690 ft).

Artist's concept of the replacement bridge. Source: Renzo Piano studioMajor repairs were made to the bridge between 1992 and 1994 after inspections showed that concrete stays had degraded, particularly around a bridge element known as pylon 11. A general restoration project was taken on, including structurally reinforcing the concrete stays of pylon 11.

The repairs added both long and short cables for each concrete stay. The long cables were located along the vertical faces of the concrete stays and were linked to them by means of steel ties that were fixed on the top of the pylon to steel caps. They were also fixed under the bottom of the transverse beam to steel plates.

The short cables were located on the sub-horizontal faces of the concrete stays, and were fixed to the lower parts of the concrete stays by way of steel checks.

The Morandi viaduct after its August 2018 collapse, which killed 43 people. Source: File image.In the repair design, the short cables also had the temporary function to bear all the load of the bridge as the old strands were cut away. More permanently, they helped to regulate the stress level in the concrete stays.

The replacement stay cables were made with unbonded strand encased in a high-density polyethylene duct. Their design allowed for them to be checked, tension regulated and replaced either altogether or strand by strand.

Part of a Morandi-designed bridge in Venezuela, which was built using a similar design to the one in Genoa, collapsed in 1964 after being hit by a ship.