BALTIMORE, Md. — We all saw it captured on camera, and engineers will study it for years to come - the moment the Key Bridge collapsed.
And as we speak, leaders in the field asking two questions: could this happen again, and if so, can we prevent it?
That includes Greg Shafer, Bridge Technical Manager at Parsons in Baltimore, and Paul Wiedefeld, Maryland Department of Transportation Secretary.
So, question one - could this happen again?
"It's very difficult, if not impossible, for a structure to be impacted by a vessel of that magnitude going that speed and not incur significant damage and possible collapse," Shafer tells WMAR-2 News.
But ships of that size, going that speed, travel through our waterways every day. And thousands of bridges, just like the Key Bridge, were designed and built before that was the norm. The Key Bridge was built in 1976.
"We also need to recognize the scale of the ships and, you know, the laws of physics are the laws of physics. So,we have to think through, you know, to what level could we possibly prevent something like this from ever happening again?" Wiedefeld said.
That takes us to question two - can we prevent it?
"Well, designing a bridge for a direct impact from a vessel the size of the Dali is never going to make sense," Shafer said. "It's a somewhat academic exercise to say whether it could be done or not. And we could have that discussion. However, there are ways to protect it. The thing is, we need to think of this as a system. We have to make sure the ship stays in the channel first of all, and that if it doesn't for some reason that there are ways to protect the bridge from the vessel actually getting there [...] It could be rock islands in the in the river, it could be what we call dolphins, which are concrete filled areas that would stop a ship before it ever got close to the bridge.”
Shafer also says shallow water in the area near the bridge's foundation could help prevent a ship from getting too close - i.e. if a vessel can't float into an area, and it runs aground before it gets to the bridge structure.
Dolphins, or islands, are examples of what's called a pier protection system. The National Transportation Safety Board is currently investigating what kind of system, if any, the Key Bridge had in place. But NTSB Chair Jennifer Homendy has already said - the bridge wouldn't have been designed the same way today.
"The bridge is fracture-critical. What that means is if a "member" fails, that would likely cause a portion of, or the entire bridge to collapse. There's no redundancy. The preferred method for building bridges today is that there is redundancy built in," Homendy said at a press conference on March 27, the day after the bridge collapse.
So, are fracture-critical bridges more suspectible to ship strikes? Shafer says no.
"In my personal opinion, I don't think the fact that this was a fracture critical bridge had anything to do with the collapse. It had everything to do with 110,000 ton vessel hitting a major support."
There are more than 17,000 fracture-critical bridges in the U.S., out of about 615,000 bridges total. Shafer says that number shouldn't worry you.
"The term fracture critical is really scary, right? You hear that word and you say, 'oh my gosh, that must be really bad.' We know a lot about these and we look at them differently. They are inspected on a much more frequent basis and maintenance is done in a different way such that any defects are addressed early and don't become a problem."
The demise of the Key Bridge has turned a lot of Marylanders focus to the Bay Bridge, which is also fracture-critical. That includes members of the Department of Transportation. Secretary Wiedefeld says the department is already looking at ways to make it safer.
"Well, there's some things in the short term that we're looking at, you know, what can we do in the short term? And then there's others longer term things. You may be aware actually we have a study to replace the bridge down there. So thinking of, you know, what we learned from this, obviously, would go into that as well."
"The Bay Bridge is the most exposed, some say, because you know there's many ships coming up the bay that have to pass underneath that. And I'm sure there'll be a lot of look at that to make sure that we're doing the best things, that we're taking care of them the best way possible," Shafer said. "Regarding other bridges in Maryland, I don't see that many that are really exposed to a particular risk like that." But when it comes to managing risk, the burden doesn't fall solely on bridge engineers. Like Shafer said, it's a system, and ships are a part of that system.
NTSB Chair Homendy recently said in Senate testimony, after the 1980 collapse of the Sunshine Skyway bridge in Florida, the NTSB issued recommendations to the Coast Guard to evaluate pier protection systems against shipping traffic in various U.S. waterways.
"The U.S. Coast Guard stated at the time that it did not have the authority to do that so it was never done.”
"And this is a critical thing and we do this often - coordination with the Coast Guard and the Army Corps when we're building a bridge and I think that can be enhanced and that we can look at safety in a different way. How do we manage vessel traffic to help make it safe as one prong in the way that we protect bridges?" Shafer said.
As for re-building the Key Bridge, that will also entail re-designing it. Secretary Wiedefeld confirms it will not be a truss-style bridge like it was. It will be a cable-stayed bridge, which is considered standard today. MDOT anticipates the bridge will be rebuilt by 2028, with a price tag ranging between $1.7 and 1.9 billion.