Baltimore's Francis Scott Key Bridge Collapses after Ship Strike

[Borg]

Major bridge in Maryland collapses after being hit by a ship

The entire center sections of the bridge are in the water after a container ship directly struck one of the support pylons this morning.

 

[Borg]

Given the location, I can't see how they can operate the harbor at this point. There is no way in or out now.

 

[Baluncore]

Closed, yes.
The main span is now blocking the dredged and marked channel.

 

[PeroK]

How could this happen?

 

[Borg]

Good question. Most large ports have harbor pilots who board the vessels and are responsible for navigation. I would assume that Baltimore would have them.

 

[Baluncore]

How could this happen?

The way it broke apart suggests it was lacking redundancy.
Built in 1972. Now a 52-year-old steel structure, in a salt water environment.
The picture here shows exposed and vulnerable support columns.
https://en.wikipedia.org/wiki/Francis_Scott_Key_Bridge_(Baltimore)

 

[PeroK]

The way it broke apart suggests it was lacking redundancy.
Built in 1972. Now a 52-year-old steel structure, in a salt water environment.
https://en.wikipedia.org/wiki/Francis_Scott_Key_Bridge_(Baltimore)

I was thinking more how could a massive cargo ship collide with a bridge?

 

[russ_watters]

I was thinking more how could a massive cargo ship collide with a bridge?

Steering/general control failure would be my guess.

 

[russ_watters]

The way it broke apart suggests it was lacking redundancy.

I mean....one pair of piers, sure.

 

[Rive]

Steering/general control failure would be my guess.

My first bet is on human error, as usual

 

[Baluncore]

The weather was calm and clear.
Ships have failures of their steering gear.
Commands get misinterpreted.
People suffer from medical events.
The dredged channel is close to the vulnerable Southern main support columns. It appears Dali was in the channel, but turned to the South.

Red squares mark the channel, three on either side.

DALI (IMO: 9697428) is a Container Ship and
is sailing under the flag of Singapore.
Her length overall (LOA) is 299.92 meters and
her width is 48.2 meters. Draught: 12.2m.
Gross Tonnage 95,128. Summer Deadweight (t) 116,851.

 

[russ_watters]

155,000 ton container ship. Similar to an aircraft carrier.

Source: radio

 

[russ_watters]

My first bet is on human error, as usual

As others have suggested, it's a really tough error to make.

 

[russ_watters]

Red squares mark the channel, three on either side.
View attachment 342367

Slight clarification: those markers are for the pylons, and are not on the edge of the channel. The channel is 215 ft inside the pylons (per NOAA chart).

 

[ChemAir]

Wow.

A lot worse than the crawl on the local news was describing.

I think the article said there were two pilots on board.

 

[gleem]

The last time it needed to change its course was 3.5 mi up harbor passing over the Baltimore Harbor tunnel, after that it is a 3.5 mi straight channel under the Key bridge. The main span is 1200 ft so the channel is about 770 ft wide using @Russ-watters data Container ships are notoriously hard to turn I would not have expected the speed to be over 10 kts. Having said this if it was an ebbing tide it might have been moving faster. Still It had 3.5 miles to line up the channel or stop. With GPS nav electronics it is hard to see they weren't perfectly lined up 3 miles from the bridge.

 

[russ_watters]

CNN is reporting multiple instances of lights flickering in the few minutes before the crash, possibly indicating power failure. And it strayed off course just 2 min before the crash.

 

[russ_watters]

...CNN is reporting the ship issued a Mayday call and traffic to the bridge was shut down prior to the collision. This likely saved a lot of lives.

 

[russ_watters]

Here's a snip from the chart and a link to the source:

https://www.charts.noaa.gov/OnLineViewer/12281.shtml

 

[Borg]

My original MSNBC link is now showing this as the path.

 

[sophiecentaur]

The way it broke apart suggests it was lacking redundancy.

Very worrying. There are (game) simulations availlable that show exactly that sort of catastrophy but there's no suggestionthat they represent real life. How wrong can you be?

Was it a Boing problem?

 

[trainman2001]

There was a failure on the ship. Period. What the failure was is not know yet, but this ship had been involved in a collision in the past, and damage could have been remaining.

As for the bridge collapsing: Cantilever structures are a delicate balancing act. They're not designed to have one pier taken out. When you watch the sequence, once the first part fell, it was pre-ordained that the rest was coming down. When they're built, they start at the piers and build outward from each equally and carefully so it stays balanced. It's also being supported by the arch which also is built from the piers meeting in the middle. It was a 165,000 ton ship, not a barge. Bridges have been hit by barges and lived to tell the tail. With this vessel, it was a death blow.

The challenge now is building a completely new bridge that wasn't even on the drawing board. It will not be replaced by a cantilever with its forrest of steel girders all riveted/bolted/welded together. It will probably be a cable-stayed bridge which can be built somewhat faster. We had a new cable-stayed bridge built parallel to the existing I-65 bridge from Louisville to Indiana and all points north. Walsh construction did it in under 3 years and on budget. They are a terriffic company to do it.

But this was a bridge that was on the books for a while. In this case, they have to design it from scatch. The bridge was only 52 years old so it was not slated for replacement. That's going to take time before they build the first caisson. It's probably going to take five years. And they have to demolish the mess that's there now. That's going to take months to do. It is the classice worst case scenario.

There was a bridge replacement on 1-64 across the Kanahwa River near Charleston, WV. After building the new span (concrete prefab on concrete piers replacing a steek arch bridge) the old bridge was deconstructed and it took months with some very heavy barge cranes doing the work. This bridge is at least 5X the size and is partially submerged, all of which adds to the challenge greatly.

 

[phinds]

The challenge now is building a completely new bridge

Yes, and there are already comments that the new one will have much larger protective barriers in front of the pillars so this cannot happen again.

The bridge being down in the water is a huge problem for the port of Baltimore, and this will have a serious affect on commence. What will also have a big effect on commerce is the inability of commercial road traffic to use that route up the East coast of the US. It is heavily traveled. Well, it WAS. Today not so much, I guess.

PLUS, of course, the air is going to be really heavily polluted by the massive amount of cussing that the lack of this major traffic artery for non-commercial vehicles is going to cause.

 

[berkeman]

Was it a Boing problem?

Please don't do that; it's very inappropriate.

 

[Baluncore]

The water is very shallow, 5 or 6 metres, except for the dredged channel where it is closer to 15 or 20 m.
That seems to be the ideal situation for a concrete immersed-tube tunnel.
https://en.wikipedia.org/wiki/Immersed_tube
The Baltimore Harbour Tunnel is an early small immersed-tube tunnel, opened in 1957.
https://en.wikipedia.org/wiki/Baltimore_Harbor_Tunnel

 

[berkeman]

Yes, and there are already comments that the new one will have much larger protective barriers in front of the pillars so this cannot happen again.

Sorry, how in the world can we possibly build big enough protective pillars in front of the bridge pylons that a huge cargo ship will not damage the bridge? Reactive armor comes to mind, but that's several MT of reactive armor, IMO. And the channel will still be clogged afterwards...

 

[phinds]

Sorry, how in the world can we possibly build big enough protective pillars in front of the bridge pylons that a huge cargo ship will not damage the bridge? Reactive armor comes to mind, but that's several MT of reactive armor, IMO. And the channel will still be clogged afterwards...

The channel wouldn't be clogged if the ship were entirely off to one side of the channel and the bridge were still unharmed.

As to how such barriers could be effective, I have no idea. I was just passing on what I heard an engineer say on a talk show. My assumption was that they would be massive mini-islands with large concrete pylons sunk down to bedrock, BUT ... that's an assumption. I am not a structural engineer. I believe there are similar thingies at other major bridges, but I could be wrong.

The bridge pilon stopped the ship. Why couldn't what I describe do it?

 

[Baluncore]

Sorry, how in the world can we possibly build big enough protective pillars in front of the bridge pylons that a huge cargo ship will not damage the bridge?

You do not have pillars, you have shallow water and rock around the towers.
The ship will ground before it gets to a tower.

 

[Vanadium 50]

CNN now reports a power failure on the ship, beyond just "flickering lights".

There are multiple reports of six people missing, presumed dead. Two survivors.

This part of the world seems to build the bare minimal number of bridges. There are few good alternatives.

A ship this heavy has a lot of momentum, and thus a lot of force when it smacks into something. It's hard to see a simple design alteration will change this fact.

 

[Tom.G]

Please see https://www.physicsforums.com/posts/7071909

Which proposes a blown engine.

[edit:] starting 2:34 in the video posted by @DaveE below (1:25:42 EDT)

Cheers,
Tom

 

[DaveE]

 

[Borg]

According to the Washington Post, the black smoke may have been a backup diesel generator kicking in.

The 985-foot container ship, known as the Dali, left Baltimore about 12:30 a.m. Tuesday, bound for Sri Lanka. Clay Diamond, the executive director of the American Pilots’ Association, said the ship experienced a “full blackout” around 1:20 a.m., meaning it lost both engine power and electrical power to the ship’s control and communications systems.

The ship was traveling at 8 knots, a normal speed for the area that Diamond described as “ahead slow.” The ship never regained engine power, but Diamond said a diesel backup generator did kick in, restoring the electrical systems — the possible source of a puff of black smoke visible in video of the collision circulating on social media.

 

[Filip Larsen]

You do not have pillars, you have shallow water and rock around the towers.

As I understand it, this is a fairly common and well-known option for collision protection on (newer) bridges, so do anyone know the specific reason why that protection was not selected for this bridge?

 

[Rive]

As I understand it, this is a fairly common and well-known option for collision protection on (newer) bridges, so do anyone know the specific reason why that protection was not selected for this bridge?

Old bridge, old standards for (lot) smaller ships of old times?

 

[Filip Larsen]

Old bridge, old standards for (lot) smaller ships of old times?

There is of course an age aspect of that question, but it was constructed around 1972 so not all boats were small at that time, and establishing protective zones is something I would imagine can be added or augmented long after a bridge has been constructed so I would guess there are other more compelling reasons it was not done. I was thinking possibly candidate reasons could be cost (always a factor one way or the other), environmental impact (although that is a much newer concern, but one that is addressed quite often now when marine constructions are proposed in the area I live) or perhaps the tides in the bay would wreck havoc on any attempt to raise the seabed?

The reason I ask is because I am just curious, but I foresee this question quickly becoming relevant when a new bridge has to be constructed, as it likely comes with a requirement that collapse from potential collisions must now be extremely unlikely.