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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

#341

Post by brazzy »

oldgradstudent wrote: post #132
questinthrow wrote: post #23

What was the ship captain's plan here? Just ram through the bridge?

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.

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

#342

Post by rayiner »

This is going to have a huge impact on traffic patterns in the mid Atlantic. The bridge carries 695 (the Baltimore beltway) across the river. Although I95 goes through Baltimore, 695 is one of two major bypass routes that’s a more direct shot from places south of the city to places north of the city (the other being the Baltimore harbor tunnel carrying 895). Unlike the Philadelphia bridge span collapse recently, I don’t foresee this bridge being rebuilt anytime soon.

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

#343

Post by brazzy »

lmm wrote: post #31
questinthrow wrote: post #23

What was the ship captain's plan here? Just ram through the bridge?

Looks like the captain might have had little control and/or been distracted, what with the ship being on fire at the time.

The smoke was likely from the engines running at full reverse to avoid the collision. But the ship lost power (you can see its lights going out in the video) and thus the ability to steer.

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

#344

Post by WarOnPrivacy »

Reason077 wrote: post #279
JohnBooty wrote: post #245

Earlier quoted context omitted.

It certainly does not seem reasonable to design a bridge pillar to withstand a direct impact from a massive cargo ship. But I guess I thought that maybe there was... typically some kind of earthen buffer around the pillar to prevent such an impact? That's probably impractical too, I guess. I guess I just didn't realize ~$1bn bridges were one fluky ship accident away from total collapse at any given time. I think mayb…

When Florida's Sunshine Skyway bridge was partly collapsed by a similar incident in 1980, the replacement bridge was built with a series of "structural dolphins" and concrete barriers to protect against ship strikes. You can see them in the image linked below: https://en.wikipedia.org/wiki/Sunshine_Skyway_Bridge#/media/...

> the replacement bridge was built with a series of "structural dolphins" and concrete barriers to protect against ship strikes.

Given how the Skyway collapse is burned into the local consciousness, I suspect some of the benefit comes from their visibility.

I truly don't know how the dolphins would fair against a massive ship strike but I can imagine them doing their job.

(ship passing): https://pbs.twimg.com/media/FPgQhy2X0AE8yw1.jpg

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

#345

Post by tekla »

b33j0r wrote: post #208
Retric wrote: post #187

Earlier quoted context omitted.

Bridges only last for roughly 50 years. Considering such collisions are rare enough to make the news as a memorable event you can workout for yourself that the odds are quite low over a bridges lifespan. They are designed to withstand smaller boat impacts because they occur relatively frequently, but cost vs benefit on rare events that are difficult to mitigate is quite different.

Interested in this claim, because it sounds about right, except that I can’t name a bridge constructed in the past 50 years. The bridges we can all name are pushing 100+ right?

I can't imagine how it is to be so insulated from the world to not be able to name a single major bridge construction in the past 50 years.

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

#346

Post by serf »

b33j0r wrote: post #208
Retric wrote: post #187

Earlier quoted context omitted.

Bridges only last for roughly 50 years. Considering such collisions are rare enough to make the news as a memorable event you can workout for yourself that the odds are quite low over a bridges lifespan. They are designed to withstand smaller boat impacts because they occur relatively frequently, but cost vs benefit on rare events that are difficult to mitigate is quite different.

Interested in this claim, because it sounds about right, except that I can’t name a bridge constructed in the past 50 years. The bridges we can all name are pushing 100+ right?

vincent thomas bridge in LA is from 1960 -- old but not 100+

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

#347

Post by ToucanLoucan »

zeteo wrote: post #337
dathinab wrote: post #202

Earlier quoted context omitted.

At least in the links with the video now you can see that the container ship directly hits one of the two main (and in the central area only) pillars completely collapsing it. No matter(1) the engineering there is no pretty much way to not lose the whole large middle area and left area leading to the destroyed pillar in that situation. Such a collapse crates so much force (tension vibrations etc.) so that the collaps…

You don't need to build the bridge to an absurd strength, but it may have been insufficiently marked as a navigational hazard. Something like a few well-lit pillars 500 feet upstream in the water would have given the ship plenty of warning to change course, since a vessel travelling at 5 knots takes about a minute to go 500 feet. The total bridge length is on the order of 10,000 feet, so widening the safe area around…

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.

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

#348

Post by litenboll »

xoa wrote: post #296
dathinab wrote: post #202

Earlier quoted context omitted.

At least in the links with the video now you can see that the container ship directly hits one of the two main (and in the central area only) pillars completely collapsing it. No matter(1) the engineering there is no pretty much way to not lose the whole large middle area and left area leading to the destroyed pillar in that situation. Such a collapse crates so much force (tension vibrations etc.) so that the collaps…

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 started moving extremely slowly, and all of us except one tried to hold back the force of the train, which of course was imossible and dangerous. The one who did not try to push it very quickly found the "shoe" and put in place. Initially it did not seem to help at all, the train just continued moving at the same pace, tearing up asphalt with the shoe. It finally came to a stop after about 3-5m(?) which takes a fair bit of time with such low speed, and felt like forever given the situation.

The train tracks headed out into an open road, so it could have been so much worse if it were not for the only person thinking clearly in the situation (he was one of the more experienced in our group).

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

#349

Post by [deleted] »

Lance_ET_Compte wrote: post #331
TaylorAlexander wrote: post #66

Somehow I find it surprising how completely the bridge collapsed after the damage. I understand that a container ship collision is serious, but you could imagine a scenarios where the bridge slumps or buckles but doesn’t just disintegrate like that. It’s surprising that ships capable of doing this damage were probably regularly driving past it, and its safety as a thoroughfare depended entirely on those collisions no…

In 2013, a tanker ship hit the Bay Bridge (Oakland SF) but didn't do much damage. In 2007, another tanker (Cosco Busan) hit the same bridge dumping oil into the bay: https://www.youtube.com/watch?v=upfjxfl2nRM . We have a new bridge there now because that one was also damaged in the Loma Prieta earthquake. When the Golden Gate needs replacement, the Marin NIMBY's that didn't extend BART to the north bay are going to…

[deleted]

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

#350

Post by [deleted] »

btbuildem wrote: post #338
tokai wrote: post #285

Insane that the pylons wasn't protected by artificial islands.

If you think about this for a minute, you'll realize that what you're asking for is pretty much impossible. What would these artificial islands be made of? Sand, gravel, concrete rubble? This is a river, the constant current of the water erodes anything that resists it by staying in place. Piling up enough material to resist erosion and create a meaningful obstacle to 70000 tonnes in motion, that would significantly…

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