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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

#851

Post by dragonwriter »

FredFS456 wrote: post #768
dboreham wrote: post #763

Earlier quoted context omitted.

This seems like a system architecture error. Boats do weird shit sometimes and so bridges need to be deigned to not fall down when a boat crashes into them. Requiring a huge boat to be steered to meter resolution when clearly that's not always going to happen is top shelf stupidity. Up there with backup generators in the basement below the water table.

My civ engineer friend says that bridges are supposed to have barriers in front of their pylons for this particular reason - in the event of a collision, the barrier would be destroyed but not the pylon.

Some bridges have fenders, my understanding is that with existing brudges whether they can be retrofitted, even if resources exists, depends on the channel and the kind of traffic it needs to handle, because they take up soace that can be nontrivial in a tight channel.

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

#852

Post by dragonwriter »

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.

The Key Bridge had dolphins but not fenders, some descriptions since the incident have indicated that it has fewer dolphins than some other bridges.

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

#853

Post by [deleted] »

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.

[deleted]

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

#854

Post by berniedurfee »

Is it feasible to run large ships on autopilot? Large airliners land mostly on autopilot now, right?

Seems like a somewhat solvable problem to combine a bunch of sensor inputs to keep the ship inside of a safe corridor, such that even a loss of power would be accounted for to ensure it would drift safely.

Is it a much harder problem than my intuition assumes? Cost issue?

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

#855

Post by salawat »

DiggyJohnson wrote: post #669
myself248 wrote: post #488

Earlier quoted context omitted.

At least in small craft, bow thrusters are usually electric, with local batteries charged from the main engine room. I don't know what large craft are like, but it doesn't seem unreasonable that a bow thruster may remain operable even if the main engine fails. Clearly that's not required or they would've had it and used it, but it could be required if the regulations didn't suck. Furthermore, steering could absolutel…

> That a ship with so much more destructive potential is allowed to operate without the same level of redundancy as a $90k Audi, is unconscionable. Would you still believe this if it was demonstrated that the system lacking redundancy was - due to factors beyond the scope of this conversation - more safe by an order of magnitude than the steering system that includes redundancy but in a different medium? Put differen…

Ejection seats are a use case noche unique to military flying where the pilot is A) the most irreplaceable piece in terms of warfighting, and B) injury of the pilot in the escape attempt is considered an acceptable tradeoff.

If you really want chills, think about this: a conscious decision was made with covil aviation that it was more economically feasible to sacrifice the human lives on board, and resolve the rest through lawsuits.

In short: if you know/are critical to the process of murdering extra-natiomals, you warrant a life saving device.

If you're a civillian, you're a line item in a potential series legal judgements.

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

#856

Post by acdha »

berniedurfee wrote: post #854

Is it feasible to run large ships on autopilot? Large airliners land mostly on autopilot now, right? Seems like a somewhat solvable problem to combine a bunch of sensor inputs to keep the ship inside of a safe corridor, such that even a loss of power would be accounted for to ensure it would drift safely. Is it a much harder problem than my intuition assumes? Cost issue?

The early reports suggest that the ship was having trouble actively maintaining position - some have theorized a stuck rudder or wind pressure – in which case the only thing an autopilot could do is make the situation worse. I’d wait for the full investigation to come out before speculating about fixes.

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

#857

Post by ClumsyPilot »

forgetfreeman wrote: post #644
animex wrote: post #592

Earlier quoted context omitted.

You can train for it, then how many years into your career you actually experience such a scenario are you likely to act instinctually and recover. The best solution would be to improve autopilot assist as it will never forget how to correct (if possible).

Nope. The military, aerospace, and medical industries have all refused full automation in life-or-death situations with cause.

Isn’t that interesting when compared with ‘machines don’t make mistakes’ wisdom

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

#858

Post by serf »

rightbyte wrote: post #575
jcgrillo wrote: post #555

Earlier quoted context omitted.

I'm not sure what configuration of props a ship like this has, but in my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. I've read that some large ships also are direct drive--there's no transmission between the engine and the propeller, so "reversing" (if it's even possible) entails shutting down the engine and restarting it in reverse. This can be don…

> my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. I have to protest here. Reversing and using the rudder on a 40ft boat works perfectly fine. I've done it on multiple sailing boats. You need to hold tight so that the rudder wont slap you if using a stick.

>I have to protest here. Reversing and using the rudder on a 40ft boat works perfectly fine. I've done it on multiple sailing boats. You need to hold tight so that the rudder wont slap you if using a stick.

this is a stupid argument from all users , comparing a 40ft sailboat to other 40ft sailboats is like making a broad assumption about cars when comparing a dragster to an SUV simply because they have a similar singular aspect.

ANY sailboat, regardless of size, can have poor reversing performance just simply due to its hull shape and rudder plan. Some boats famously cannot reverse with authority due to the turbulence created between the parts. Some boats use feathering propellers which collapse inwards when reverse is applied in order to make a more efficient sailing experience, which effectively makes propulsion reversing useless.

There is NO generalized '40 foot sailboat' in existence. They all act different, and there are some that are perfectly capable of doing what other 40 foot plans might consider IMPOSSIBLE.

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

#859

Post by [deleted] »

justin66 wrote: post #795
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…

> More than a train going from full speed to a full stop. I wonder. This ship might have massed about ten times a typical freight train on the heavy side, but the train is going to be moving a lot faster than a ship navigating in port, right?

[deleted]

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

#860

Post by onthecanposting »

mikeyouse wrote: post #386
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.

Older bridges no, but newer bridges should absolutely. The Bay Bridge was struck in 2007 and came away mostly unscathed due to earlier efforts to prevent catastrophic damage in that scenario; https://en.m.wikipedia.org/wiki/Cosco_Busan_oil_spill Though the Maryland accident looks like it struck it dead on - just a massive amount of energy to absorb.

Yes. Dolphins and protective features for this sort of scenario are more standars now.
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