Italy collapse points to difficulties with aging bridges

New York: The bridge that collapsed in the Italian port city of Genoa was considered a feat of engineering innovation when it was built five decades ago, but it came to require constant maintenance over the years. Its design is now being investigated as a possible contributor to its stunning collapse.

The Morandi Bridge was severed in its midsection during a heavy downpour Tuesday, killing at least 39 people. Italian prosecutors focused their investigation into possible design flaws or inadequate maintenance of the 1967 bridge.

Engineering experts said the disaster points to the challenges of maintaining any aging bridge, regardless of its design.

"What the general public does not comprehend is that bridges have been traditionally designed in the past for a life span of 50 years," said Neil Hawkins, a professor emeritus of engineering at the University of Illinois, who specializes in reinforced and prestressed concrete design. "The environment in which the bridge exists can have a major effect on how much it can last beyond that 50-year design life span." The structure is a cable stayed bridge designed by Italian engineer Riccardo Morandi, who died in 1989.

Among its unusual features were its concrete-encased stay cables, which Morandi used in several of his bridge designs instead of the more common steel cables. There are two similar bridges in the world, in Libya and Venezuela.

Experts have said a number of factors could have contributed to the collapse, including wear and tear from weather and traffic that surpassed what the bridge was originally built to sustain. "Genoa is a port city so that there can be marine effects and also it is a major industrial center so that there can be air pollution that impairs the concrete," Hawkins said in an e-mail. "Whether any of these effects, or other major deficiencies in the foundations, were present I have no knowledge. But all can contribute to a bridge failure."

Antonio Brencich, a professor of construction at the University of Genoa, said the design lent itself to swift corrosion and the bridge was in constant need of maintenance.

Most recently, a 20 million-euro ( 22.7 million) project to upgrade the bridge's safety had been approved before its collapse, with public bids to be submitted by September.

According to the business daily Il Sole 24 Ore, the improvement work involved two weight-bearing columns that support the bridge including one that collapsed

Tuesday.