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Baltimore's Key Bridge struck by cargo ship, collapses

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Re: Baltimore's Key Bridge struck by cargo ship, collapses

#751

Post by nwiswell »

HarryHirsch wrote: post #549
hgfghj wrote: post #521

Earlier quoted context omitted.

That ship had a 10,000 TEU capacity and was actually hauling a little under 5,000 TEUs. An empty container weighs a little over 5,000lbs, and a full one can be up to 67,000lbs. If you do the math, you find that it’s just an astronomical amount of momentum, and there’s no effective defense for a bridge that needs support in more than 30 or so feet of water.

there’s no effective defense for a bridge that needs support in more than 30 or so feet of water You put in sheet piling 50 meters upstream, and you fill the box with rocks. That's state of the art practice, nowadays, but that bridge was 50 years old.

The sheet piling didn't need to be 50 years old.

In 1977 (and in 1972, when construction began), vessels of this size did not exist, and certainly were not allowed in the harbor[1]. But over time, they were given authorization, despite the fact that they could collapse the unprotected bridge like a load of toothpicks.

The real crime here is that there was no retrofit to protect the pylons. It was almost certainly considered and rejected due to cost.

[1]: https://logisticselearning.com/wp-content/uploads/2022/06/Co...

The ship in question here was 10K TEU.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#752

Post by adameasterling »

boringg wrote: post #397

This is a tragedy for those involved. My rough calculus points that the amount of force of this collision is on par with a large scale natural disaster. Everyone being surprised at the bridge collapsing needs to reconcile with the amount of force that struck the bridge - it is a truly significant amount of Newtons that hit the bridge. More than a train going from full speed to a full stop. Unbelievable amount of forc…

> Everyone being surprised at the bridge collapsing needs to reconcile with the amount of force that struck the bridge ... I am also a bit surprised at how many people don't grasp this or grasp engineering, magnitude of forces and design principles.

A spokesman for CalTrans claimed today that Bay Bridge could have taken the same hit without damage, thanks to fenders that protects all pylons for all bridges in the San Francisco Bay Area (1). Cargo ships are heavy, yes, but it appears we have the technology to prevent bridge collapses due to these sorts of collisions today.

1. "The Bay Bridge’s fenders insulated the span during the 2007 incident, so that the Cosco Busan ship struck a bumper, never hitting the bridge itself, Ney said. He noted that fenders on Bay Area bridges should be able to handle a ship traveling at 8 knots, the velocity at which the ship hit the Francis Scott Key span."

https://www.sfchronicle.com/bayarea/article/baltimore-bridge...

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#753

Post by xp84 »

1letterunixname wrote: post #722
araes wrote: post #541

Earlier quoted context omitted.

Current personal suspicion after watching your linked video (excellent discussion by the wgowshipping author) is: Catastrophic engine failure (1:24) causing wide scale power loss. No rudder control, rudder drift, and ship alignment drift (1:24-1:25:30) Power restored and ship reengages prop with bad ship/ruddder alignment (1:25). However, ship is now pushing itself into a further bad turn. Pilot likely stomps the bra…

I hope the next POTUS makes good on Biden's promises because Baltimore and Maryland will need federal assistance since they can't afford such a burden. And I assume there will lawsuits to recover costs as this caused economic damage and risk to life (8 people unaccounted for at current time).

I'm kind of confused how a President can promise something like that. He doesn't have any power to appropriate money, and given his party's lack of control of Congress, I'd argue he can't promise anything.

Not to mention that one can scarcely find a "bluer" area than Baltimore -- I would assume that the most proudly right-wing politicians would be more than happy to let Baltimore suffer to score points with their polarized supporters. I hope it doesn't come to that, but they tried to block Hurricane Sandy relief, despite every hurricane in the South being an automatic 'non-partisan' emergency.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#754

Post by bmitc »

jordanb wrote: post #743
bmitc wrote: post #679

Earlier quoted context omitted.

Thanks for the link to that book. I don't know if it's the because of this catastrophe, but it looks to be unobtanium at the moment. Will have to find it in the library. > lack of redundancy This is what I am surprised at from many angles. It seems to me that the ship, the port (in the form of lack of tugboats), and the bridge (in the form of lack of secondary protection of the pillars) all had a lack of redundancy a…

The author GPLed it and put it on the internet at one point: http://martrans.org/documents/2006/safety/The%20_tankership_...

Oh, nice. Thanks for the heads up there and again for the book reference.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#755

Post by tetha »

deltarholamda wrote: post #561
danpalmer wrote: post #501

Earlier quoted context omitted.

It's somewhat counterintuitive how much energy can be in something moving so slowly. I say somewhat, because when you're up close it's much more obvious, but you're right that on a video it doesn't look like much.

This disconnect happens with boats quite a lot. For example, I can, by myself, pull a 45 foot grand banks trawler in shallow water. I know because I've done so. But at even very low speeds, I cannot stop it from hitting a pier. I have not tried to do this, but every harbor master has a bunch of stories about people trying to do so and getting a leg or an arm or something squished and pulverized. People who are not bo…

This hit me a a bit ago - you can't really tell how big ships are if you just see pictures of them on sea. I recently hit this in real life. Yeah it's a ship. Oh. It's like 3 - 4 times as tall as I am above water. And it goes 2-3 stories down. And holy hell, a crows nest 30 meters up is... really high up?

And we got the good tour, because we had a severe storm warning as we visited that ship - the kinda storm in which gusts stop you in your tracks and forces you to lean into it to not fall over. Was a great experience. I wouldn't want to be up there with that kinda wind.

And this was a medium sized clipper, somewhat on the small size.

And based off of that, I kind of want to see a retired battleship or an aircraft carrier. Because now I have an idea of how dumbfounded I'll be at those kinda dimensions. It just doesn't appear that big on photos!

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#756

Post by boringg »

bmitc wrote: post #671
boringg wrote: post #375

Earlier quoted context omitted.

Collision means nothing without magnitude of force. A glancing blow is completely different from a direct hit. And the amount of Newtons behind the blow completely changes the outcomes. A small ship versus a loaded container ship is a completely different force. I doubt many bridges would take a full speed, fully loaded container ship directly to one of their supports and survive it. Certainly the most celebrated bri…

Apparently this container ship was only half loaded to capacity. And it seems likely that a container ship would hit it given the vicinity of such container ships. I'm generally confused on this matter.

It hit the support completely dead on and stopped. All of that momentum and force went directly into the bridge. The pulse from that impact would have been enormous.

Why would you anticipate that a container ship would have to hit the bridge? What about the flip side to that... How many bridges have never been hit by a container ship or alternatively how many times have an almost fully loaded container ship come to a dead stop after hitting a bridge?

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#757

Post by frankfrank13 »

TaylorAlexander wrote: post #66

Somehow I find it surprising how completely the bridge collapsed after the damage. I understand that a container ship collision is serious, but you could imagine a scenarios where the bridge slumps or buckles but doesn’t just disintegrate like that. It’s surprising that ships capable of doing this damage were probably regularly driving past it, and its safety as a thoroughfare depended entirely on those collisions no…

Someone hasn't played enough polybridge

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#758

Post by flavius29663 »

bmelton wrote: post #396
mannykannot wrote: post #283

Earlier quoted context omitted.

> But any preventive measure will have limits as what and how serious an impact it can deal with. The recent grounding of a large container ship in Baltimore's harbor channel demonstrates that a sufficiently massive berm will stop any ship. What's needed is the will to do something about low-probability but catastrophic events (though large-ship collisions, groundings and fortuitously harmless steering failures are f…

Starting from xoa's calculations above, assuming you can pack a berm with well-compacted soil enough that it can absorb 1,000 joules per cubic meter, you'd need a buffer of something like 10 meters surrounding each piling with 3 meters of depth to keep it safe from this kind of impact. That's 10 meters in every direction from the center of the support -- let's assume the support has a thickness of 0 meters for the sa…

You should look at the deisgn of old stone bridges. Their side facing up ( so towards the floods and ice) is like a wedge pointed upwards. So it's not like he bridge needs a buffer to fully stop all the forward energy. It can lift the object out of the water and maroon it there.

e.g. https://www.japantimes.co.jp/uploads/imported_images/uploads...

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#759

Post by samstave »

samstave wrote: post #542
hgfghj wrote: post #521

Earlier quoted context omitted.

That ship had a 10,000 TEU capacity and was actually hauling a little under 5,000 TEUs. An empty container weighs a little over 5,000lbs, and a full one can be up to 67,000lbs. If you do the math, you find that it’s just an astronomical amount of momentum, and there’s no effective defense for a bridge that needs support in more than 30 or so feet of water.

Thank FN gosh that those TEUs were likely ~mostly empty returns. If thems be full, that guy would be illegally parked for far longer. -- What is the traffick-routing-around plan look like? (both sea and land, helicopters cry in lack of TEU)

Jeasus - seriously - if that was an inbound shipment then it would be worse - this appears to have been leaving - which would infer that the TEUs were more empty than full.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#760

Post by boringg »

dghlsakjg wrote: post #502
boringg wrote: post #367

Earlier quoted context omitted.

Why are you throwing shade at civil structural engineering? Do all bridges we build need to be able to withstand the force of an entire shipping container bridge hitting it at high speed? What planet should an engineer think that a shipping container has managed to veer off course so badly that they hit a bridge at full speed, fully loaded? That is a sad and significant outlier event.

This is a common joke in engineering. It’s not meant to be an insult, but a compliment noting that engineers know what the essential parts of the bridge are

I suspected it might be but I couldn't tell from the post. There is a lot of self deprecating humor amongst engineers / engineering programs.
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