Animation showing planned Key Bridge explosive demolition unveiled
BALTIMORE — Francis Scott Key Bridge cleanup officials shared a video animation Wednesday depicting how crews plan to deploy small explosive devices to clear a large steel truss resting on the bow of the Dali container ship in the Patapsco River.
Crews will cut holes into various sections of the truss and place thin pieces of metal inside those holes — with small explosive charges attached — according to the one-minute animation. Each charge will be protected by a wrapping, “similar to a large piece of tape,” the video says.
All of the small explosives will detonate simultaneously, creating cuts that are “merely millimeters in width.” Observers might see small flashes and puffs of smoke, according to the animation.
The cuts will rend apart the truss section and send the pieces plunging into the river, unpinning the Dali.
“It’s important to note that this controlled demolition is not like what you would see in a movie,” says a voice-over on the animation released Wednesday. “From a distance, it will sound like fireworks or loud thunder and appear as puffs of smoke.”
Key Bridge cleanup officials are recommending that any individuals within 2,000 yards of the blast site use hearing protection. Most of that area is within the Patapsco River.
“There is a small portion of the noise radius that includes land over the industrial portions of Hawkins Point,” Chief Petty Officer Nicholas Carr, Key Bridge Response Unified Command safety officer, said in a news release Wednesday. “We are ensuring workers in the area have advanced notice of the plan.”
For individuals outside that radius, the sound will “be no louder than a standard fireworks show” and will last two to five seconds, according to the news release from the Key Bridge Unified Command center. Officials have been using the term “precision cutting” to describe the operation.
“Precision cutting offers one of the most efficient and safest methods to be able to remove steel under such a high level of tension,” the release reads. “This highly controlled process enables surgical precision.”
Crews are aiming to complete the detonation in the coming days, possibly as soon as this weekend, according to the Unified Command. Officials plan to send out a notice 48 hours before the detonation. Weather conditions and other variables could change the timeline.
Controlled Demolition Inc., a company based in Baltimore County’s Phoenix, will be handling the operation, as a subcontractor of Resolve Marine, the cleanup company assigned to the Dali. Controlled Demolition Inc.’s president declined to comment, deferring questions to the Unified Command.
The company has extensive experience with explosives in demolition, including local projects such as the demolition of the C.P. Crane power plant, and larger operations like the cleanup following 9/11 and the Oklahoma City bombing.
James Milburn, president of the National Demolition Association, which represents demolition and wrecking companies, said using explosives is a highly specialized field within the industry.
“There’s a limited number of professionals that have the experience and licensing for explosive demolition,” said Milburn, who is also the managing principal for Milburn Demolition, with offices in Chicago and Tampa. “So a lot of us — in terms of demolition contractors — we subcontract out that scope to these individuals.”
A number of different considerations likely went into the decision to use explosives to free the Dali, rather than making individual cuts with saws, which has been done for many of the pieces of steel sitting in the Patapsco River, Milburn said. Chief among them is likely the safety of the workers involved, who would probably have to saw at the steel while suspended from cranes, officials have said.
“If it were safer to do this removal with mechanical methods, then it would certainly be done that way,” Milburn said. “But safety and cost in mind — and speed — there’s a reason that they’d be using those (charges).”
Contractors typically look to use the least amount of explosives as possible but still achieve the desired effect: in this case, allowing the truss to fall into the water so the Dali can be refloated. This case also comes with other complexities, like ensuring the Dali remains stable during and after the detonation.
“I would say they probably have an explosive demolition plan that would note the location and the size of the charges and the protections required around the charges to limit debris or steel from shooting out too far from the site … and if there’s any added protection or stabilization required for the boat,” Milburn said.
The wrappings on top of each charge help prevent too much debris from being emitted as clouds of smoke and encase and focus the explosion, he said.
“What they want to do is guide the explosive to the piece of metal or structure they want to be severed,” Milburn said. “It’ll almost look like — if I had to guess — it’ll look like localized fireworks.”
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