Baltimore bridge collapse

[Earthdweller]

That’s just incredible and almost unbelievable that a modern bridge would suffer such a catastrophic failure from a single strike on a support

I suppose we should be thankful that it appears to be an accident rather than a deliberate act

[LimaDelta]

stuckmojo said:

I have senior experience in maritime, and this troubles me deeply.

The sequence of things to have to go wrong for this accident to happen is not small.

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

1 minute is easily 150/200m, which with anchors, would allow at least a massive speed reduction.

Incredible. Literally incredible.

Events like these - up to 30 seconds to the "interaction" - are rare but do happen. there is an enormous amount of literature on what to do.

Normalisation of deviance.

Perhaps blackouts were a common occurrence on that vessel, which meant the Captain was happy to wait a minute for restoration rather than dropping the pick and having to have a chat with the shoreside office. The problem was the power restoration didn't happen (or didn't happen quick enough). A crash stop (there is a big puff of black smoke, which could have been an astern command) would take some time to stop the vessel, even at low speeds like this (and reduce rudder effectiveness as the vessel slows).

Plus there is the Swiss cheese effect - no one failure should allow this, but line up enough of the holes - engineers fatigued after a maintenance period (main engine work can only happen in port so often big jobs are concurrent to cargo loading/unloading), midnight departure, circadian rhythm low, pressure to leave on schedule, incorrect response from bridge team, power failure and slow restoration, NE winds push the vessel to the south, etc. etc. Loads to unpack and speculate on, but as you say the MAIB report will make interesting reading for sure.

[Digga]

stuckmojo said:

eharding said:

I have no idea how these things are arranged, but can these vessels drop anchor on command from the bridge in the event of a power failure, or would you need someone to be already up at the bow to hit something with a large hammer to release the anchor chain? Would you typically have someone stationed up there as a part of standard procedure when leaving port?

you can have a "dead ship" - It happened to some of my fleet when I ran one - and you can always drop the anchor.

When it happened to "me" it was always away from harbour.

Power loss near infrastructure and close to quay = anchor.

in simple terms

https://www.marineinsight.com/guidelines/9-points-...

Edited by stuckmojo on Tuesday 26th March 12:05

From what I've read in comments on Twitter, the hydraulic anchor drop on these large, commerical vessels is (necessarily) totally independent of electrical power systems.

As I said above, my maritime knowledge extends only as far as a Hobie Cat.

[pingu393]

Hammersia said:

Lotobear said:

LimaDelta said:

ro250 said:

Be interested to hear an engineer's view on the collapse as I was surprised to see the whole thing go down, especially the first section to the right.

Enjoy - Poly Bridge Game


Edit - not meant to make light of the situation, more to educate those who are unaware how many interlinked structures rely on each other for strength and support. Take away one element and the whole lot comes down.

An absence of redundancy in the structure - probably an old design.

That footage is truly shocking

There's really no such thing as redundancy for structures like that, it will be the same result if a ship crashes into the right part of the Forth rail bridge.

The possible weak point / unluckiness in this case is that the deck level on these massive recent cargo ships protuded out far enough to catch the steel upright pillars (rather than the hull hitting the concrete abutment first).

(Example of Forth bridge with small cargo ship to give an idea)

What surprised me was the mode of failure. To my eye, the ship hit the support and sent a shockwave down the bridge. The shockwave then hit the point where the bridge failed. That part was the Jenga part that started the collapse. The failure was not at the point of impact.

This failure mode was never considered when I did my mechanical engineering degree. The closest to this mode that we studied was harmonic motion, but this was a single wave.

This may be the first time that this type of failure has been seen. If the damage were only visible now, the assumption would be that the failure was at the point of impact.

[Vipers]

Earthdweller said:

That’s just incredible and almost unbelievable that a modern bridge would suffer such a catastrophic failure from a single strike on a support

I suppose we should be thankful that it appears to be an accident rather than a deliberate act

Not surprising, they are not built to withstand being hit by a ship..

[Vipers]

stuckmojo said:

I have senior experience in maritime, and this troubles me deeply.

The sequence of things to have to go wrong for this accident to happen is not small.

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

1 minute is easily 150/200m, which with anchors, would allow at least a massive speed reduction.

Incredible. Literally incredible.

Events like these - up to 30 seconds to the "interaction" - are rare but do happen. there is an enormous amount of literature on what to do.

I doubt ordering drop the anchor and actually doing it takes time, and probably not geared up to do it just because your underway, and you need a lot of cable out to stop a ship underway.

[Vipers]

Hammersia said:

There's really no such thing as redundancy for structures like that, it will be the same result if a ship crashes into the right part of the Forth rail bridge.

The possible weak point / unluckiness in this case is that the deck level on these massive recent cargo ships protuded out far enough to catch the steel upright pillars (rather than the hull hitting the concrete abutment first).

(Example of Forth bridge with small cargo ship to give an idea)

Lucky the Forth bridge survived, when a German battlecruiser upside down with no tow line sailed under it, close call.

Mind you, it looks more sturdy than newer builds to me.

[pti]

Earthdweller said:

That’s just incredible and almost unbelievable that a modern bridge would suffer such a catastrophic failure from a single strike on a support

I suppose we should be thankful that it appears to be an accident rather than a deliberate act

I am an engineer but I'm not surprised in the slightest.

[Byker28i]

50 years since the Cleddau bridge disaster, caused by a misreading of the plans and the joints were half the thickness they were meant to be and that was as it was being built
https://www.bbc.co.uk/news/uk-wales-52878053

The the Morandi bridge collapse showed what could have happened at busy times. It's such a big, well used bridge, it's surprising the death count is so low. Time of day I guess

Edited by Byker28i on Tuesday 26th March 12:53

[Puggit]

Here come the twitter idiots...

[Earthdweller]

Vipers said:

stuckmojo said:

I have senior experience in maritime, and this troubles me deeply.

The sequence of things to have to go wrong for this accident to happen is not small.

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

1 minute is easily 150/200m, which with anchors, would allow at least a massive speed reduction.

Incredible. Literally incredible.

Events like these - up to 30 seconds to the "interaction" - are rare but do happen. there is an enormous amount of literature on what to do.

I doubt ordering drop the anchor and actually doing it takes time, and probably not geared up to do it just because your underway, and you need a lot of cable out to stop a ship underway.

Is it not possible it was so close to the bridge it might have swung round and hit it anyway?

[Hammersia]

pingu393 said:

Hammersia said:

Lotobear said:

LimaDelta said:

ro250 said:

Be interested to hear an engineer's view on the collapse as I was surprised to see the whole thing go down, especially the first section to the right.

Enjoy - Poly Bridge Game


Edit - not meant to make light of the situation, more to educate those who are unaware how many interlinked structures rely on each other for strength and support. Take away one element and the whole lot comes down.

An absence of redundancy in the structure - probably an old design.

That footage is truly shocking

There's really no such thing as redundancy for structures like that, it will be the same result if a ship crashes into the right part of the Forth rail bridge.

The possible weak point / unluckiness in this case is that the deck level on these massive recent cargo ships protuded out far enough to catch the steel upright pillars (rather than the hull hitting the concrete abutment first).

(Example of Forth bridge with small cargo ship to give an idea)

What surprised me was the mode of failure. To my eye, the ship hit the support and sent a shockwave down the bridge. The shockwave then hit the point where the bridge failed. That part was the Jenga part that started the collapse. The failure was not at the point of impact.

This failure mode was never considered when I did my mechanical engineering degree. The closest to this mode that we studied was harmonic motion, but this was a single wave.

This may be the first time that this type of failure has been seen. If the damage were only visible now, the assumption would be that the failure was at the point of impact.

I'm not seeing that in the videos. Looked more like the deck literally sliced into two of the vertical supports and gravity took over.

Edit: this video is clearer:

https://x.com/Mrgunsngear/status/17726042738151060...

Edited by Hammersia on Tuesday 26th March 13:03

[hidetheelephants]

gotoPzero said:

Very strange. There are big concrete barriers before the main bridge legs but it looks like they came at a slight angle and missed those.
The bridge is a bit longer than what you see in the video too, which is why they call it a "partial" collapse.

A ship of that size and fully loaded as it departs would slice through that bridge like butter - as we saw.

The footage of the aftermath show there's nothing left of the concrete support, it's gone right down to the water level platform; right enough it shouldn't be getting rammed by a ship but nor should it vanish completely when it does.

stuckmojo said:

I have senior experience in maritime, and this troubles me deeply.

The sequence of things to have to go wrong for this accident to happen is not small.

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

1 minute is easily 150/200m, which with anchors, would allow at least a massive speed reduction.

Incredible. Literally incredible.

Events like these - up to 30 seconds to the "interaction" - are rare but do happen. there is an enormous amount of literature on what to do.

Agree with all this; we have a idiots guide to disasters, it's a mandatory part of ship management these days, it details in check list form what to do in the event of the likely shipboard emergencies. As to the event; this appears potentially much more than a normal blackout, a blackout should not stop the main engine or affect bridge steering, the ship should have been able to proceed safely or stop well before the bridge if not.

eharding said:

stuckmojo said:

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

I have no idea how these things are arranged, but can these vessels drop anchor on command from the bridge in the event of a power failure, or would you need someone to be already up at the bow to hit something with a large hammer to release the anchor chain? Would you typically have someone stationed up there as a part of standard procedure when leaving port?

Responsibly run ships will have anchors ready to drop when in harbour or narrow channels; there would be a crew on the forecastle to do it, no controls on the bridge.

[Greshamst]

I wouldn’t like to be the insurers.

I wonder how much that’s going to cost to reinstate.

[aeropilot]

Earthdweller said:

That’s just incredible and almost unbelievable that a modern bridge would suffer such a catastrophic failure from a single strike on a support

Well, its not really a 'modern' bridge.....construction started in 1972, so the design was started in the late 1960's.........and certainly that concrete bridge pier that was struck was not designed for the impact of a size and mass of ship that simply didn't even exist back then.

If you take out a complete main concrete pier, which the ship did, then the spans collapsed entirely as expected.

What is incredible, is that the port/harbour/city have not at any point in the past 25+ years seen fit to build greater protection around those concrete support piers, which would be this vulnerable to an impact from such a ship which are now the regular users of this port. Other than the 4 small circular concrete buoy structures which house the channel navigation markers, there was no protection at all....nothing above or even below, as usually there would now be reduction in depth of the water protections so a ship would 'run-a-ground' before getting anywhere near a pier.

[hidetheelephants]

Greshamst said:

I wouldn’t like to be the insurers.

I wonder how much that’s going to cost to reinstate.

~$2bn for the bridge; daily loss to the local economy is probably millions, as will having the harbour blocked up but probably neither is covered, although enterprising underwriters of cargoes trapped or delayed will probably have a go at suing. The underwriters will get a hammering.

[Sheepshanks]

stuckmojo said:

I have senior experience in maritime, and this troubles me deeply.

The sequence of things to have to go wrong for this accident to happen is not small.

The investigation will eventually find the root cause, but if the vessel lost power more than 1 minute before the bridge, it should have dropped anchors there and then. It didn't. it restored power and lost it again, before regaining it too late.

1 minute is easily 150/200m, which with anchors, would allow at least a massive speed reduction.

Incredible. Literally incredible.

Events like these - up to 30 seconds to the "interaction" - are rare but do happen. there is an enormous amount of literature on what to do.

You could imagine the regular crew thinking they could sort it out, but there were a couple of pilots on board - how much authority do they have?

[hidetheelephants]

Sheepshanks said:

You could imagine the regular crew thinking they could sort it out, but there were a couple of pilots on board - how much authority do they have?

Pilots are advisory, the captain remains in control of the vessel and responsible for it at all times.

[Petrus1983]

Greshamst said:

I wouldn’t like to be the insurers.

I wonder how much that’s going to cost to reinstate.

Can't see it being massive in the grand scheme of things. 12 hours made a giant difference though.

[Gecko1978]

Puggit said:

Here come the twitter idiots...

I don't want to google it what is a black swan event - like the film will there be dancing