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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

#841

Post by forgotmyinfo »

randerson wrote: post #595
jcranmer wrote: post #535

Earlier quoted context omitted.

The last car crossing that I can see clears the span about 1:28:06; the bridge collapses about 1:28:48. That's about 40 seconds of gap between the traffic and the collapse. I haven't timed how frequently cars are coming, but it seems to be about every 30 seconds or so, which--combined with the time it takes to cross the bridge--is evidence that a bridge closure was effected just before the bridge collapse.

Whoever was driving that last car had better go buy a lottery ticket right away.

Honestly, that would probably fuck me up for a little while, knowing I was less than a minute away from probably being dead. I hope they're okay, mentally.

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

#842

Post by Symbiote »

tetha wrote: post #755
deltarholamda wrote: post #561

Earlier quoted context omitted.

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 whic…

The best place I've seen huge ships is Hamburg. People sit and picnic on beaches along the river in the summer, and enormous container and car carrier ships go past.

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

#843

Post by MOARDONGZPLZ »

quasarj wrote: post #788
adameasterling wrote: post #752

Earlier quoted context omitted.

> 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…

"A ship traveling at 8 knots" is a meaningless statement. You need to know how bit the ship is...

Container ship

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

#844

Post by lmm »

CydeWeys wrote: post #598
thekid314 wrote: post #597

Earlier quoted context omitted.

Was there a harbor pilot on board, or the normal ship pilot? Were there tug boats helping with the exit? I have often felt that the harbor protocols were overkill, but this is one of the times they could have helped.

All pilots are "harbor pilots". Crew members who control the ship outside of port are just called crew members (captain, first mate, 2nd Officer, that kind of thing), never pilot.

> All pilots are "harbor pilots".

I don't think that's true. The Suez Canal famously requires pilots, but isn't a harbour (I guess you could argue it functions as one). I've heard of pilots for the Great Barrier Reef which is even more not a harbour.

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

#845

Post by senectus1 »

samstave wrote: post #759
samstave wrote: post #542

Earlier quoted context omitted.

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.

do they ever run these empty?

I would expect they're as close to full as they can get in every trip. They'd be terribly inefficient ways to transport goods otherwise.

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

#846

Post by boringg »

adameasterling wrote: post #752
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…

That may be so and I appreciate CalTrans confidence in the matter. I however would never want a similar set of circumstances to strike the bay bridge and have to test it.

It is a very different bridge design (assuming were talking about the Oakland to treasure island portion) and it is built in earthquake country.

I'm not saying there shouldn't have been fenders or other protective measures. I'm saying that the amount of force on a direct hit that STOPPED that the ship dead in its tracks - that bridge was not going to withstand it and I do question what would happen to the bay bridge. Again I appreciate the confidence of CalTrans to reassure the commuters but I have seen government officials express too much confidence before.

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

#847

Post by userbinator »

elihu wrote: post #789
paddy_m wrote: post #568

Earlier quoted context omitted.

On ships like this the propulsion is separate from the steering. There is a separate rudder that is close to, but not attached to the prop and propshaft. The propshaft is fixed. The rudder doesn't just "restart in a random position" it would remain in the previous position unless there was a physical piece that broke in the rudder gear. The fact that ship was able to reverse hard ( as evidenced by the slowdown), indi…

Do big container ships like this typically just have a standard propeller/rudder without some kind of directional thruster to assist in maneuvering? https://en.wikipedia.org/wiki/Voith_Schneider_Propeller

Not this one.

https://en.wikipedia.org/wiki/MV_Dali

Propulsion Single shaft; fixed pitch propeller

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

#848

Post by hollerith »

elihu wrote: post #789
paddy_m wrote: post #568

Earlier quoted context omitted.

On ships like this the propulsion is separate from the steering. There is a separate rudder that is close to, but not attached to the prop and propshaft. The propshaft is fixed. The rudder doesn't just "restart in a random position" it would remain in the previous position unless there was a physical piece that broke in the rudder gear. The fact that ship was able to reverse hard ( as evidenced by the slowdown), indi…

Do big container ships like this typically just have a standard propeller/rudder without some kind of directional thruster to assist in maneuvering? https://en.wikipedia.org/wiki/Voith_Schneider_Propeller

Usually tugboats attend whenever a large container ship enters or exits a busy port, and the tugboats have directional thrusters. Port authorities prefer it that way because it gives them more control (since the tugboats tend to stay in the port).

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

#849

Post by userbinator »

pja wrote: post #838
reaperman wrote: post #778

Earlier quoted context omitted.

I can’t find any bridges which have a barrier that can protect against a fully loaded container ship. I have seen plenty of barriers which would protect against personal watercraft and smaller working ships like smaller tugs/coast guard ships/shrimping boats, etc. But a loaded container ship at 8 knots is not going to be stopped by anything remotely feasible. Container ships weigh between 50,000 and 220,000 tons. A U…

https://en.wikipedia.org/wiki/Dolphin_%28structure%29?wprov=... If they're designed to stop a bulk carrier then presumably they can stop a container ship.

That article gives an example of being hit by https://en.wikipedia.org/wiki/MV_Summit_Venture

deadweight tonnage of 33,912, gross tonnage of 19,735, and a net tonnage of 13,948.

The one that took down this bridge:

https://en.wikipedia.org/wiki/MV_Dali

Her registered gross and net tonnages are 91,128 and 52,150, respectively, and her deadweight tonnage is 116,851

Many times larger.

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

#850

Post by Spooky23 »

ClumsyPilot wrote: post #591
mixedmath wrote: post #290

Earlier quoted context omitted.

I'm not sure if I would expect any bridge to survive being struck by an enormous container ship.

I would and furthermore I think there is a massive bias at play - if the exact same disaster happened in China there would be jokes about bridges made of Chinesium. There is an expectation that a disaster happening in the west in a result of unforeseeable act of god, but in China it will be a result of corruption or shoddy workmanship. Whereas in reality maintenance standard in the west have fallen but in the east th…

Well everyone involved in the design of this bridge is long dead.
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