Morandi bridge, or the Polcevera Viaduct, built in the 1960s over the Polcevera river in Genoa, Italy, with a span of 1,182 meters, connects France with Italy along the A10 motorway. A tragic collapse of the 260 m deck section of this viaduct in 2018 killed 43 people and necessitated the need for reconstruction of the four-lane bridge. The demolition and reconstruction activities for the Polcevera Viaduct (now also known as Geonova San Giorgio Viaduct) were completed in August 2020 and the bridge was opened to traffic on August 5th. The bridge serves as a critical link connecting Genoa to other European transport corridors.
The Polcevera Viaduct is a fundamental feature of an important transport network in Genoa and the Liguria region of Italy. It is part of the southern corner of the Milan-Turin-Genoa industrial triangle, which is an important economic center. The fatal collapse of this viaduct in 2018 resulted in severe economic losses in the region, including the closing of three rail routes, thereby adding 120 kilometers to the road journey of regular commuters. In order to restore normalcy, the Italian Ministry of Transport decided it was necessary to rebuild the viaduct on a tight schedule and restore the traffic flow. Italferr S.p.A., part of the Italian State Railways Group (Ferrovie dello Stato Italiane), was chosen by the Pergenova Consortium Companies (group responsible for the design and construction of the Viaduct) to design the emergency replacement of the Polcevera Viaduct.
The reconstruction of the bridge came with various challenges, including the difficult terrain of the location that was surrounded by four city roads, residential plots, a railway line and the river beneath it. Additionally, the design of the project had to be completed within three months and it was a challenge to finalize the same for a project of such size and complexity in that small a window. The project also had to adhere to the new Italian safety standards for curvature radii of entrances and junctions, along with a cross-section of the deck.
The reconstructed Polcevera Viaduct designed by Renzo Piano – the man who designed the London Shard ─includes a total of six two-lane carriageways and two additional emergency lanes. The cost of the reconstruction was EUR 202 million (USD 239.9 million). The bridge is supported by 18 elliptical reinforced concrete piers. The continuous metal girder has a total span of 1,067 meters, with steel concrete spans of varying lengths, as mentioned below:
Italferr S.p.A conducted an initial survey of the viaduct construction site using drones equipped with LiDAR scanners. The point cloud data was supplemented with Orthophotos to create the Digital Terrain Models (DTMs) of the construction site. The data triangulation of field surveys, along with digital terrain models, helped in developing a 3D model of the surface. The 3D information model was created using parametric modeling of individual components, enabling precise and accurate assembly of the components. To determine the exact volume of construction material needed, the team used LumenRT for visualizing the process, thus speeding up the construction activity. The 3D model was dynamic, so it was able to automatically accommodate and update any changes by the design team or the consulting organization. Additionally, the project team created the design for the entire infrastructure using MicroStation, OpenRoads, and OpenBuilding Designer, which provided the project team with a higher quality of design than what would have been produced with 2D maps.
The available information from the 3D model was used in computational BIM models, which enabled the team to create 4D scripts, including dimensions (length, surface area, volume), work breakdown structure (WBS) identification codes, and building materials. Using SYNCHRO, Italferr automated and optimized the 4D scripts processes, which were previously done manually. Through automated processes, the design team was able to carry out real-time geometrical and dimensional checks, ensuring accurate positioning of objects and components while shortening the design time and providing added value to clash detection and management.
Additionally, since the project involved multiple stakeholders, collaboration and coordination was imperative. In this context, the design team used Bentley System’s ProjectWise, which provided them with an open Connected Data Environment (CDE), helping them manage multi-disciplinary data and information flow across the project teams. Using ProjectWise, the collaboration through CDE made the design process efficient and improved decision-making. Using Bentley’s BIM methodology, a digital twin model of the viaduct was created to streamline information workflow across the project lifecycle. The single Federated Digital Twin model ensured a single source of truth, while also improving clash detection and incorporating new safety standards that ensured the project timeline was maintained. Using 4D visualization in the Digital Twin environment enabled the designers to accelerate design decisions, reduce design costs, improve coordination between teams, and increase accuracy.
The new bridge structure includes the latest technological advances, including:
These additional features are poised to enhance the structure’s aesthetics, maximize durability, improve energy efficiency, and ensure safety of road traffic.
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