Transit Tragedy

Morandi Bridge collapse raises questions about the future of concrete

International Transportation
The Morandi Bridge in Genoa, Italy, collapsed this week (Anna Positano)

The Morandi Bridge in Genoa, Italy, collapsed yesterday, apparently struck by lightning during a period of heavy rain, and about 30 people died and several others were injured. A viaduct on the A10 motorway, it was built between 1964 and 1967 and became a symbol of Italian post-World War II development. The bridge was designed by talented structural engineer Riccardo Morandi, then a prominent figure along with other Italian designers, including Pier Luigi Nervi and Sergio Musmeci. Morandi designed a similar project in Venezuela several years earlier.

The entire viaduct was about one kilometer in length with a maximum span of around 200 meters. It consisted of a reinforced concrete structure with hybrid pre-stressed cable-stayed spans. Aside from its elegant design, it succeeded functionally because of its three piers that allowed it to fly over the existing buildings below. The viaduct was apparently weakened because the concrete was mixed with the incorrect viscosity, which created wave-like movement in the vehicle deck. Over the years, new steel cables were introduced to reinforce the inefficient pre-stressed stays while the whole bridge was facing constantly increasing traffic, reportedly more than 25 million passages a year, nearly four times the number initially planned. A proposed bypass highway project to decrease truck transit had been discussed since 2009, but local committees—apparently the 5 Stelle (5 Stars) populist movement governing Italy jointly with nationalist Lega Party since last June—rejected the proposal, with a sarcastic mention of “the fairy tale of the collapsing bridge.”

More recently, in 2016 independent senator Maurizio Rossi sent the former minister of transportation a written Q&A that pointed out potential structural issues of the bridge and highlighted the maintenance of the viaduct as a critical matter to be dealt with by Società Autostrade (formerly the State Highway Company). Professional engineers and designers have also suggested that reinforced concrete micro-fractures in the structure created by shaking from overloaded traffic were the potential reason for the collapse.

Will this finally be a turning point for concrete as a hybrid construction material for bridges? It has long been seen as a poor material used by modernist egos for its formal plasticity even though it fails in durability. The Morandi Bridge was a national symbol of elegance and a crucial piece of infrastructure, and its collapse demands an appropriate infrastructure policy that deals with maintenance, management, and public procurement. This will avoid similar mass-murder. This is true not just in Italy, but worldwide since reinforced concrete is the most common material for bridges all over the planet.

In the meantime, social media has been filled with self-proclaimed structural engineers insulting each other, stimulated by divisive politicians.

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