It started with a hunch and some back-of-the-envelope calculations.
Shortly after a massive container ship, named the Dali, collapsed the Francis Scott Key Bridge, a couple of Johns Hopkins engineers wondered about the probability of such an event. Their hypothesis: It was more likely than previously believed.
That thought resulted in a request to the National Science Foundation — which awards Rapid Response Research grants for projects with “severe urgency” — leading to the funding for a study. Three Hopkins professors, four Hopkins undergraduate students, two doctoral students and one Morgan State University student have begun an “urgent assessment of the country’s bridges, particularly the larger ones near major ports of entry.”
Their research comes as the National Transportation Safety Board — the agency investigating the collapse of the Key Bridge — has encouraged the nation’s bridge owners to act swiftly in protecting their assets from a similar fate.
The Dali lost power March 26, crashing into the Key Bridge, knocking it down and killing six construction workers. Since then, authorities have rushed to clear the blocked shipping channel and begin the process of designing and rebuilding the bridge. It’s slated to cost between $1.7 billion and $1.9 billion and be completed by 2028.
But other bridges could be at risk. Container ships have continued to grow in recent decades and massive vessels, often weighing more than 100,000 tons, frequently transit under bridges on their way to ports in America, like the thousands of trips ships made annually under the Key Bridge.
It took extraordinary circumstances for the Dali to strike one of the bridge’s integral support piers: The ship lost power at the exact wrong time, precipitating the collapse.
But Hopkins engineers hypothesize that the risk of the Key Bridge disaster was “underestimated” and that the probability of a similar incident is higher than currently presumed, according to a news release.
“We need to know now, not five or 10 years from now, whether there is an outsize risk to bridges across the country so that critical investments — which will take years — can begin immediately if they are needed,” Michael Shields, the Hopkins engineer leading the team, said in a statement. “The Key Bridge collapse was a wake-up call.”
The engineers and students will analyze the probability of a cargo ship the size of the Dali straying from its path and colliding with the Key Bridge and the odds of similar collisions at other bridges. Their focus will be on bridges near major ports, including the Bay Bridge.
The study will take a year, but the team expects to share some preliminary findings this summer.
When the Key Bridge was designed and built in the 1970s, the nation’s bridge code — developed by the American Association of State Highway and Transportation Officials — did not have guidelines for preventing vessel collision. Those specifications were added in the 1990s, but existing bridges, like the Key Bridge and the Bay Bridge, were not required to be retrofitted to meet the new standards.
Last week, experts met in College Park for a roundtable hosted by the American Society of Civil Engineers and the University of Maryland’s engineering department. Some suggested that the nation’s bridge code could be revised because of the Key Bridge collapse. The Hopkins study could be relevant to any potential changes considered.
“The team’s findings will be crucial in reassessing and potentially redefining the safety standards for transportation infrastructure,” Hopkins engineer Ben Schafer said in a statement.
However, the study’s focus will also be on “assessing existing bridge infrastructure,” Shields said in an interview.
Current bridge code dictates that, in any given year, a new bridge’s chance of collapse from vessel collision is less than once in every 10,000 years. But many bridges might not be up to that standard, the engineers hypothesize.
“Preliminary findings already challenge prevailing assumptions,” Hopkins engineer Rachel Sangree said in a statement. “The U.S. 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.”