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Johns Hopkins engineers launch urgent assessment of US bridges

Engineers from Johns Hopkins University have launched an assessment of bridges across the US, with a focus on larger ones near major ports of entry. Their decision follows the complete collapse of the Francis Scott Key Bridge in the Patapsco River outside Baltimore Port after it was struck by container ship Dali, which brought to a halt activity in the US’s ninth-largest port and which could have an eventual insured cost of between $2bn and $4bn.

The team, funded by a National Science Foundation Rapid Response Research grant, and assisted by a group of students, will seek to modernize risk prediction models to keep pace with the growth of shipping, especially the rise in the number of large containerships.

Team leader Michael Shields is a Johns Hopkins engineer specializing in risk assessment. He said that “we need to know now, not five or 10 years from now, whether there is an outsized risk to bridges across the country so that critical investments can begin immediately if needed”.

Shields noted that the risk to bridges such the Key Bridge in Baltimore had changed significantly since they were built, which meant that the current understanding of the risks was insufficient.

The team suggested that the risk of such a bridge collapse was underestimated and that the likelihood of similar catastrophic collisions in the US is potentially much higher than current design standards anticipate.

The team will work with global shipping data to develop contemporary risk models. One aim will be to identify vulnerable bridges susceptible to catastrophic ship collisions. They also aim to build models to assess the likelihood of a ship deviating from its course and hitting a bridge near major ports.

Team member Rachel Sangree, a structural engineer and former bridge inspector, said that “preliminary findings already challenge prevailing assumptions. The US has seen 17 incidents of major bridge collapse between 1960 and 2011, averaging one every three years. Between the exponential growth of mega freight ships and the surge in global shipping traffic, many of our bridges simply weren’t built to withstand the pressures of today’s maritime landscape”.

Structural engineer Ben Schafer said that “given the estimated $1.7bn to $1.9bn cost to rebuild the Key Bridge and the potential billions needed to retrofit existing bridges, accurate risk assessment is vital to ensure the sustainability of society’s critical infrastructure”.

Some preliminary results are likely to be shared with interested parties by the end of the summer. The full study is expected in about a year.

The US is being extremely cautious at the moment with container ships near bridges, ever since the Dali allided with the Francis Scott Key Bridge in Baltimore on March 26th. In a separate rate development, marine liability rates were estimated to have risen by 10% to 15% since the Dali event.