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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

#811

Post by kortilla »

dboreham wrote: post #763
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…

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.

Top shelf stupidity is thinking a container ship’s momentum can be stopped by normal barriers.

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

#812

Post by pgwhalen »

low_common wrote: post #523
tokai wrote: post #377

Earlier quoted context omitted.

I have thought about it for hours by now, and read literature on the matter. It is definitely possible to build berms that protects a bridge from catastrophic failure in case of a ship collision, and it is widely done during modern bridge construction. Please be less sure of yourself when you clearly don't have any actual knowledge on the subject.

"I have thought about it for hours by now, and read literature on the matter." Ah, the classic, pompous Hacker News user. The Baltimore Port Authority should've hired you to prevent this disaster - you're a genius!

Seriously, this comment has to be satire.

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

#813

Post by jml78 »

paddy_m wrote: post #574
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…

To anyone reading this who isn't an experienced boater: If you are invited onto someone else's boat, sit down and shut up during docking, don't talk to friends, let the captain concentrate. Don't help, if the captain wants you to do something, they will let you know. If you think you know better than the captain, and this advice is unknown to you, you don't know better. Being a good guest during docking shows experie…

Take things slow so you aren’t the show.

I have a 44ft sailboat. Docking is not easy. People do not realize how difficult it can be

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

#814

Post by peterleiser »

lenerdenator wrote: post #453
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…

How common are power outages on ships? I get that the captain might not have responded to it correctly but that seems like a thing that shouldn't happen, at least in my completely uneducated opinion.

I was curious about power outages as well, and why tugboats aren't required for all container ships that navigate under bridges. I'm not arguing that tugboats MUST be mandated; just wondering about the cost/benefit analysis. This claims that power outages are more common now (but doesn't cite sources/stats) in areas (specifically California) where diesel fuel is required, rather than bunker fuel: https://baykeeper.org/news/column/tugs-test-towing-giant-shi... It also makes it clear that relying on tugboats to be on standby and "swoop in to the rescue" is seriously wishful thinking where bridge safety is concerned. This article from 2019 is about a power failure due to an Oil Mist Detector that didn't have a "harbour mode" option of keeping the engine running at reduced RPM so you can still maneuver. It also shows the link between engine failure and a need for tugboats under "lessons learned": "– Although it is tempting to free harbour tugs as quickly as possible, in the restricted waters of a small port their assistance can be invaluable should something go wrong." On the other hand, what safety or economic issues do tugboats cause? It will probably become a topic of discussion or investigation at least.

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

#815

Post by bmitc »

boringg wrote: post #756
bmitc wrote: post #671

Earlier quoted context omitted.

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…

According to a quick search and reporting due to this event, apparently a quick number is a few dozen full collapses in the past 55 years, which doesn't seem to account for impacts and collisions that didn't result in full collapses. So that seems like a lot of bridges indeed, along with a lot of deaths and economic impact.

The reason why I would anticipate a container ship hitting that bridge is because of the video we've all seen. It's a huge ship that is going the slowest it can while still retaining control over the vehicle, unattended, through a tight spot, close to a bridge with zero protection from ship collisions, and all with a ship design that is apparently (according to other comments) effectively impossible to correctly maintain and keep running at all times. So I think the better question is, why wouldn't you anticipate a collision?

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

#816

Post by ithkuil »

amluto wrote: post #685
moritonal wrote: post #586

Earlier quoted context omitted.

When you play about with game engines long enough, you start to realise that momentum is the key metric to track rather than speed. Especially in water magnitude can be very deceiving but to give some quick math, this vessel had a momentum at impact of about 154,000,000kg⋅m/s. For a car to have equivalent momentum it'd have hit the bridge at 156,580 mph. Humans are just less adept at appreciating mass vs velocity.

Energy matters, too. That hypothetical car has the order of 1 kiloton of TNT of kinetic energy. The resulting blast would have been large. (This is about the estimated yield of the Beirut explosion.) I would rather get hit by a slow moving object than a fast one with equal momentum.

If you're moored on the ground you'd be torn apart in both cases

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

#817

Post by organsnyder »

jml78 wrote: post #813
paddy_m wrote: post #574

Earlier quoted context omitted.

To anyone reading this who isn't an experienced boater: If you are invited onto someone else's boat, sit down and shut up during docking, don't talk to friends, let the captain concentrate. Don't help, if the captain wants you to do something, they will let you know. If you think you know better than the captain, and this advice is unknown to you, you don't know better. Being a good guest during docking shows experie…

Take things slow so you aren’t the show. I have a 44ft sailboat. Docking is not easy. People do not realize how difficult it can be

Given how hard I find docking my 16-foot bowrider if there’s more than a light breeze, I can only imagine.

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

#818

Post by Etherlord87 »

bastardoperator wrote: post #494
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…

The video is surreal, it looks like it barely bumps the bridge and 2 seconds later the entire thing is gone. I don't know what I was expecting, the bridge just looked extremely fragile, makes me wonder what other bridges are at risk of an event like this.

I remember when I was a kid, I left a bus, and the bus started moving, and I, not being intimidated by the bus moving very slowly (somewhere between 5 and 10 km/h), didn't move a safe distance away from the bus. I think the bus, due to the nature of its maneuverability, had its tail moving not in parallel to me but slightly towards me - so when it has "touched" (hit?) me, even though I thought it was just sliding in parallel, the force was so strong I made a full 360° turn - and I was a tall and chubby boy.

I ended up with no injury, not even a bruise as far as I can remember (who would count bruises as a kid), but definitely with an intuition to respect mass.

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

#819

Post by mckn1ght »

litenboll wrote: post #348
xoa wrote: post #296

Earlier quoted context omitted.

Just to put some numbers on this: The MV Dali (IMO#9697428) is a little over 95000 GT, or ballpark-ish probably around 114000 tons loaded (and it seems to have been loaded, which would make sense on departure). If it was going even 5kn (2.6 m/s) that'd be about 300 million newton-seconds, or about 3.3 times the momentum of a large jumbo jet like a 747 shortly at cruising speed (around 560 mph). It'd still have the sa…

I had a summer job once, filling trains with sugar. They weighed about 15kkg per wagon (usually 5-10 wagons per train IIRC). One time the pulling cart broke down and we had to switch it for another, but when we took it off the rails we forgot about the "shoe" that is supposed to go between the rail and one of the wheels so it can't move downhill (it was like 1degree of slope so barely recognizable as a slope). It sta…

> all of us except one tried to hold back the force of the train

This reminds me of a vivid memory I have. I’d just finished a shift cooking, and out back of our restaurant there were railroad tracks. I had a beer and smoke out there with my shift mate, and a train was rolling by. I thought it would be fun to practice jumping on the train. So I do a few passes jogging alongside it, hopping on and off. Then my buddy, standing still, reached out and grabs a rung of a ladder on one of the cars. It immediately picked him up, but he gripped harder due to being startled. He got ragdolled through the air about 10 feet from where he was initially standing.

Kids, don’t play with trains (trespassing issues aside).

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

#820

Post by sackbut »

kortilla wrote: post #811
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.

Top shelf stupidity is thinking a container ship’s momentum can be stopped by normal barriers.

I’ve see pictures of the barriers before the accident and they were there, but they looked like they were tailored to 70s era ships not the container laden ships of today
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