Baltimore's Key Bridge struck by cargo ship, collapses • Hacker News Board

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

#591

Post by ClumsyPilot » Tue, Mar 26, 2024, 6:23 PM UTC

mixedmath wrote: post #290

AndrewKemendo wrote: post #287

Earlier quoted context omitted.

I agree. I lived in PG county for years and this is a big deal The 295 bridge collapse a decade ago was similarly shocking U.S. infrastructure is beyond crisis level.

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 they improved.

So now this bias protects responsible decision makers from legal consequences - no one went to prison for grenfell disaster, postmaster scandal or the Boeing debacle.

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

#592

Post by animex » Tue, Mar 26, 2024, 6:23 PM UTC

lotu wrote: post #587

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…

> How many pilots, trained or not, really have any experience with a 100,000 ton ship in a crash situation with responses where seconds matter? I would expect anyone piloting such a ship in a harbor/under bridges. We requite airline pilots to train for many unlikely plane failures because the alternative is letting planes crash that we could have saved with better training.

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).

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

#593

Post by ClumsyPilot » Tue, Mar 26, 2024, 6:24 PM UTC

callalex wrote: post #531

myself248 wrote: post #490

Earlier quoted context omitted.

A lot of bridges have their pilings set on mini islands, terrifically reinforced piles of stone and concrete that extend for quite some distance around the actual support. I don't know why some are built without that, it always weirds me out seeing the spindly legs going straight into the water, and this is why. Edit to add: Check out Fort Carroll, precisely such an artificial island just a few hundred yards away in…

Civil engineering is very complex and doesn’t go off of feelings. I’m sure the type of soil and rock that the bridge is built on inform such decisions.

There is this other thing that’s very complex- getting budget from the local government to fix something

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

#594

Post by jcgrillo » Tue, Mar 26, 2024, 6:26 PM UTC

OJFord wrote: post #497

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…

Apparently (this is just via someone on Reddit who supposedly heard/read it somewhere) the ship mayday'd on losing power hoping the bridge could be cleared. But why not (or did it?) also just blast its horn repeatedly, drawing attention so people on or near the bridge would notice it and realise something was wrong and perhaps even where it was headed? I'm sure it's not allowed generally and not the protocol and what…

Blasting the horn repeatedly is not a standard signal, but there are standard signals which might apply to a situation like this, for example "vessel not under command", "collision imminent", "vessel reversing", etc.

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

#595

Post by randerson » Tue, Mar 26, 2024, 6:26 PM UTC

jcranmer wrote: post #535

JohnMakin wrote: post #525

Earlier quoted context omitted.

They keep reporting this, and maybe it was because the video was sped up, but it looked like there was still traffic going across until very close to the collision

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.

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

#596

Post by BWStearns » Tue, Mar 26, 2024, 6:28 PM UTC

jcgrillo wrote: post #555

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'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…

Since they were still moving forward while gunning it in reverse the rudder would still operate normally. They generally have bow thrusters too. I have no idea whether they could have been operational with the broader power/engine failures but if they were available I'm sure they were being used as well.

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

#597

Post by thekid314 » Tue, Mar 26, 2024, 6:29 PM UTC

paddy_m wrote: post #568

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…

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…

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.

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

#598

Post by CydeWeys » Tue, Mar 26, 2024, 6:31 PM UTC

thekid314 wrote: post #597

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…

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.

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

#599

Post by sierrah » Tue, Mar 26, 2024, 6:31 PM UTC

animex wrote: post #592

lotu wrote: post #587

Earlier quoted context omitted.

> How many pilots, trained or not, really have any experience with a 100,000 ton ship in a crash situation with responses where seconds matter? I would expect anyone piloting such a ship in a harbor/under bridges. We requite airline pilots to train for many unlikely plane failures because the alternative is letting planes crash that we could have saved with better training.

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).

Lol you're right, controlling a ship with human inputs is so hard that is was the inspiration for a Russian shipmaster to create PID control

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

#600

Post by kazinator » Tue, Mar 26, 2024, 6:32 PM UTC

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.

Probably most of them. A structure like that not designed to bear vertical loads, not lateral ones, other than high winds.

The knee is like this too. It lets you stand, run and jump just fine, but you can knock down an opponent with a relatively mild lateral impact to the knee.

Much more of the bridge collapsed than you might think, though, far from the impact.