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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

#441

Post by btilly »

0xbadcafebee wrote: post #226
yosame wrote: post #197

Earlier quoted context omitted.

Do you mean 50 years without maintenance? I would be shocked if major bridges weren't designed to last indefinitely.

Depends on the bridge. Steel and concrete bridges can last for at least 100 years. But it depends on the environment, its expected use, the construction, design. Some famous major bridges failed early due to poor design or poor construction, but many still fail due to lack of maintenance. The average age of a bridge in the USA is 43 years. But we also have an epidemic of unmaintained bridges. No bridge made today is…

According to https://www.fhwa.dot.gov/bridge/, the federal government oversees more than 610,000 bridges in the USA. There are a lot of unmaintained small bridges. But I'd hope that the major ones get more attention.

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

#442

Post by secstate »

paddy_m wrote: post #438

Youtube tracking analysis from a knowledgeable mariner. He says that at about 1:24 AM the ship loses power (from video feed) while traveling 8.5 knots. at 1:25.30 power is restored. at 12:25.59 the ship shows smoke. The ship has already drifted in the channel. It is believed that at this time the ship applied full reverse power as evidenced by the black smoke. (My analysis: the ship drifted but hasn't turned in the c…

Does that mean this was effectively captain error? Like in response to a power outage the decision was made to try to reverse and rather than arrest forward momentum it just pushed their forward vector into the piling?

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

#443

Post by oldgradstudent »

brazzy wrote: post #341
oldgradstudent wrote: post #132

Earlier quoted context omitted.

Usually, a harbor pilot guides the vessel when entering and leaving the harbor. The pilot is a former captain with a lot of local experience. https://en.wikipedia.org/wiki/Maritime_pilot [Edit: The association of Maryland Pilots even has the bridge on their homepage https://www.mdpilots.com/ ] Did the pilot screw up? Was the pilot ignore? Did the captain take over? Was there a technical fault that disabled steering?…

It's clearly visible in the video that the ship loses power twice before the collision.

That could be an effect of aggressive attempts to regain control rather than the cause, though.

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

#444

Post by kossTKR »

nytesky wrote: post #416
ToucanLoucan wrote: post #347

Earlier quoted context omitted.

I've seen close-up video where you can see the ship losing electrical power twice for not-insubstantial times as it approaches the column. I suspect that was a much larger factor in the collision than anything the crew may or may not have done. Warning time doesn't mean shit if you can't steer.

https://twitter.com/ChaudharyParvez/status/17725385394958090... Posted video of power loss. Also black smoke coming out rear — is that normal? Any clue of what onboard crisis they were dealing with?

It seems traffic has stopped in the last moments before the hit?

Also looks like it's emergency vehicles in standstill that are falling, i can't discern any moving cars at collapse?

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

#445

Post by paddy_m »

secstate wrote: post #442
paddy_m wrote: post #438

Youtube tracking analysis from a knowledgeable mariner. He says that at about 1:24 AM the ship loses power (from video feed) while traveling 8.5 knots. at 1:25.30 power is restored. at 12:25.59 the ship shows smoke. The ship has already drifted in the channel. It is believed that at this time the ship applied full reverse power as evidenced by the black smoke. (My analysis: the ship drifted but hasn't turned in the c…

Does that mean this was effectively captain error? Like in response to a power outage the decision was made to try to reverse and rather than arrest forward momentum it just pushed their forward vector into the piling?

I would tend to think so. The pilot should have anticipated prop walk and known that the ship had no chance of stopping before the bridge.

I’m trying to find a color coded current map. Wind too. I wouldn’t expect wind or current to cause the pronounced heading change that is visible. The drift seems possible.

Note: I’m an experienced dinghy/keelboat sailor, but lack virtually any experience driving boats under power, much less commercial vessels

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

#447

Post by boringg »

sickofparadox wrote: post #429
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…

It's likely that a lot of people don't understand just how huge these ships are. I'd imagine that much of HN doesn't have a ton of firsthand experience with shipping yards or even close friends/relatives that work on these things. In my experience, almost nothing hides just how large it is than a giant ship.

That's fair. If you don't live in a major port city you likely don't understand.

Maybe we should reframe it to a more familiar territory. It could be the equivalent of a second tier unsophisticated, unsuspecting, dated website with a relatively small amount of traffic hitting it being hit by a state sponsored actor DDoS attack and expecting the website to survive.

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

#448

Post by secstate »

paddy_m wrote: post #445
secstate wrote: post #442

Earlier quoted context omitted.

Does that mean this was effectively captain error? Like in response to a power outage the decision was made to try to reverse and rather than arrest forward momentum it just pushed their forward vector into the piling?

I would tend to think so. The pilot should have anticipated prop walk and known that the ship had no chance of stopping before the bridge. I’m trying to find a color coded current map. Wind too. I wouldn’t expect wind or current to cause the pronounced heading change that is visible. The drift seems possible. Note: I’m an experienced dinghy/keelboat sailor, but lack virtually any experience driving boats under power,…

yeah, noted. But it does seem like the heading change was so dramatic and the smoke pouring out after power recovery that something happened with the prop. And while it may have been currents, the lack of heading change before the smoke seems to suggest there was an intervention that caused heading change.

Ship travel, much like orbital mechanics, are so often non-intuitive if you're not familiar with how much effort it takes to make significant speed changes vs. heading changes. And speed changes often affect the heading as well if you're not careful.

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

#449

Post by ben7799 »

brazzy wrote: post #336
jillesvangurp wrote: post #110

Earlier quoted context omitted.

I just watched the footage. It's pretty horrifying. The whole bridge collapsed in a few seconds. It's a pretty long drop down to the water. Anyone on that bridge ended up in the water with little/no warning. That drop alone would injure/kill many. And immediately after people would be in cold water still locked in their vehicles. The water there was deep enough to be able to deal with loaded container ships. So, tens…

> The water there was deep enough to be able to deal with loaded container ships. So, tens of meters at least. There are only a handful of ships in the world with a draft of more than 20 meters. The ship involved in the collision has a (maximum) draft of 15 meters.

Doesn't really matter. You can drown in 1 meter.

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

#450

Post by ZanyProgrammer »

rpeden wrote: post #157
mvdtnz wrote: post #147

Earlier quoted context omitted.

Not unlikely? Can you point us to all the other times this has happened? You must know of several given your knowledge of how obviously likely this is.

It's not especially common, but the Sunshine Skyway Bridge in Tampa Bay is a famous example. Similar circumstances - it collapsed after being hit by a ship.

that collapsed almost 40 years ago, which really emphasizes it's flat out uncommon, no "buts" needed.
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