Six construction workers were still missing and presumed dead on March 27 following the collapse of the Francis Scott Key Bridge in Baltimore, as the US Army Corps of Engineers and US Coast Guard mobilized to train a pollution response and maritime rescue plan.
The immediate goals, in addition to recovery operations, are to remove parts of the steel superstructure that crashed into the Dali ship’s bow and to reopen the port of Baltimore.
“As this aspect of the response moves into recovery operations and consistent with the president’s direction to get the port up and running as soon as possible,” Vice Admiral Peter W. Gautier said at a news conference. “The Coast Guard’s highest priority is to restore the waterway to shipping, stabilize the motorboat Dali and remove it from the site.”
National Transportation Safety Board investigators have recovered the ship’s black box.
Gautier added that under the leadership of the Corps, divers and remote unmanned vehicles are conducting underwater analyzes to mitigate any threat of pollution. “The vessel is stable, but still has 1.5 million gallons of oil” on board, he noted. The Dalí was carrying 4,700 cargo containers, he said. Two went overboard but are not considered dangerous, while 13 bow containers were damaged by the fallen bridge.
“The real crux here is that a portion of the bridge remains on the bow of this ship, and we will be coordinating very closely with the Army Corps of Engineers and their contractors to first effectuate the removal of that debris before that the ship can be removed,” he said.
The ship channel in Baltimore Harbor remains blocked by debris from the fallen bridge.Drone image courtesy of NTSB
Transportation Secretary Pete Buttigieg said it was too early to give cost estimates or timelines for the bridge or port facilities. However, the Port of Baltimore typically spends $100 million to $200 million each day, with 8,000 jobs and $2 million in wages affected by the shutdown.
Provisions in the Jobs and Infrastructure Investment Act “allow us to start releasing funding while the cost is being determined” for all the recovery work, he said, noting that a request for aid funding from ’emergency from the Maryland Transportation Authority had arrived just before the press conference. . “We are processing it immediately,” he said.
shop noted that the IIJA authorized an emergency relief account, of which $950 million was available, but had many applicants. “We probably go back to Congress to top up the funds, but that’s not a barrier for the next few days to get the ball rolling.”
Noting that the original construction of the bridge took five years, he added that it would not necessarily take five years to rebuild it. “When we helped Pennsylvania and California quickly reopen I-95 and I-10, respectively, there was some fantastic work, but it was relatively short overland bridge spans relative to this stretch over the ‘water,’ he said. “And, of course, in the case of Baltimore, we still don’t fully know the condition of the parts of the bridge that are still standing or that have infrastructure that’s under the surface of the water. So rebuilding doesn’t it won’t be quick or easy or cheap, but we’ll get there.”
Biden gave “clear direction to remove any barriers, bureaucratic and financial, that would affect the schedule,” he added.
After the 2007 collapse of the 2,000-foot-long Interstate 35W Bridge, a continuous truss structure in Minneapolis, a new bridge was built in less than two years. The Francis Scott Key Bridge, also a continuous truss, was 8,636 feet long.
Research launches
The National Transportation Safety Board is leading the investigation with support from the US Coast Guard and other agencies, NTSB Chair Jennifer Homendy told reporters on March 26.
According to a former NTSB member, investigators will typically begin by gathering information and interviewing witnesses, then use that to prepare what the NTSB calls “factual reports.” The agency will then conduct an analysis and make recommendations to prevent a similar incident.
“The NTSB is not speculating,” Homendy had said at a news conference the afternoon after the collapse. “We offer facts. So there’s not much we can share right now.”
NTSB has a 24-person team on the scene, including Homendy and NTSB board member Alvin Brown. “This is a little bit bigger than a typical NTSB investigative team,” the former employee said. An attorney involved in the Florida International University bridge collapse investigation told ENR that the team had more than a dozen investigators. But the presence of two NTSB board members may explain the size of the group, as they generally have staff accompanying them. Baltimore’s proximity to Washington, DC, also means it will be easy to bring in additional experts as needed.
Homendy said the team includes structural engineers and bridge experts who will study the structure of the bridge and how it was built. NTSB has its own engineers on staff, and while the agency only has about 400 people, it can bring in other federal resources as needed.
Depending on what the investigation finds, the NTSB’s recommendations could relate to factors such as bridge design, inspections or maintenance. And the agency could also make recommendations related to how ships tie up outside ports, or what kind of buoys and safety measures are in the water leading to bridges.
Fender Systems Review
It is not clear what the defense system was for the bridge, but it was built before the collapse of Florida’s Sunshine Skyway Bridge in 1980 due to a cargo collision prompted new design standards.
“Every time there’s a bridge failure, we gain more knowledge about the limit states we need to consider,” says John Hillman, director of structural engineering at Kiewit. The Sunshine Skyway “brought to the fore the need for clear guidance on what is required for ship collisions.”
The construction of the Francis Scott Key Bridge also predated the design concept against progressive collapse, in which the failure of one bridge member causes a domino effect, he notes.
In addition, ships have increased in size and weight over the decades, moving from post-Panamax to Neo-Panamax. Although the Dali was not carrying cargo at full capacity, its total deadweight metric tonnage is 116,851 Neo-Panamax capacity, according to vesselfinder.com.
According to a fall 2023 finance committee report, the Maryland Transportation Authority had planned to install a fiberglass jacket protection system for the bridge columns along with a deck replacement at the end of 2029, in a three-year project.
Buttigieg noted that “modern bridges around the world are designed with features to mitigate impacts and protect piers,” but that “there is debate between [engineers] as to whether those features could have played a role in a situation like this.” He added that the impact was “100,000 tons coming into that dock at once.”
“Whether any design feature would have made a difference, we will learn more as the investigation progresses,” he said.
A U.S. bridge construction manager quoted an email from Ian Firth, a British structural engineer and bridge designer, to The Baltimore Sun: “Many similar bridges are protected by barriers designed to prevent or reduce impact when a ship collides with a dock. , especially those that cross busy shipping channels where large ships like this frequently come in and out. Such facilities can take many forms, Firth said, including cable systems, pontoons, dedicated caissons tailor-made and submerged islands. But among the most widely used are dolphins, circular ball cells filled with material such as sand or concrete that essentially serve as bumpers.”
The US bridge expert added: “The river does not appear to be too deep from the images, so a rock island around each pier would have absorbed the energy and prevented the ship from geometrically hitting the structure .Most other types of dock protection would probably have been overwhelmed by the size of this vessel.Regulations need to be reviewed, just as overweight trucks need to ask if they can have a special permit to use a bridge, with more scrutiny in the assessment. The regulations should also be revised so that the environmental problems of the rock islands are not simply dismissed as environmental issues in the event that other protections do not work. We also need detectors of movement for sirens and automatic road gates when the tall ship gets too close to the docks.”
