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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

#251

Post by jalk »

onetimeuse92304 wrote: post #124
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…

Most bridges nowadays (say last century) depend on a careful balance of forces that are transferred through a chain of members in tension and compression. When any piece in the chain of those forces breaks, the entire structure loses ability to transfer forces and breaks. This arrangement is what allows us to build these structures in the first place. There is careful calculations of forces and risks and allowance fo…

Which is why many bridges have stuctures around the pillars to avoid the direct collisions

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

#252

Post by nkrisc »

wannacboatmovie wrote: post #15
ks2048 wrote: post #12

Earlier quoted context omitted.

Already roughly 75 edits since the collapse.

It makes me wonder what goes through someone's head when one sees a mass casualty event like this, and your first instinct is to rush to Wikipedia to change the article to past tense ('was' a bridge).

What should their first instinct be? Hop on an 8-hour flight to Baltimore, rent a car, drive to the scene and cross the cordon to help out?

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

#253

Post by maxerickson »

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?

Mackinac Bridge is somewhat famous, built in the 1950s.

They more or less do continuous maintenance during the warmer months of the year.

(So older than 50, but younger than 100)

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

#254

Post by _heimdall »

Hamuko wrote: post #211
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.

Doesn't the US have a problem with bridges exceeding their expected service lives?

That's a common topic here, yes, though honestly I rarely hear about a bridge collapse. I don't actually remember the last time I saw news of a bridge or overpass collapse that wasn't causes by damage like this.

Makes me want to find the data now. I don't actually known if our bridges are too old, poorly maintained and falling apart early, or if the whole topic is just herd mentality and politics.

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

#255

Post by hgomersall »

JohnBooty wrote: post #245
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…

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…

An earth buffer is just a bigger pier.

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

#256

Post by _heimdall »

mcv wrote: post #165
rpeden wrote: post #153

Earlier quoted context omitted.

Because the Port of Baltimore is a very major port, and not allowing ships under it really isn't an option. Vertical clearance for ship traffic might have been the reason this kind of bridge was built in the first place. Otherwise, something lower and more causeway-like might have been sufficient.

If it's a very major port, they can afford to make it a tunnel.

This works fine until there's a story of issues with a tunnel, then we say we should have built a bridge.

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

#257

Post by onetimeuse92304 »

lukan wrote: post #105
jack_riminton wrote: post #99

Earlier quoted context omitted.

I like this quote. We have a medieval bridge near to our house (1000 years old perhaps), it's incredibly solidly built, but could you call it well-engineered? It's a subtle distinction that I don't think many in the digital realm quite grasp either i.e. far too many over-engineered technical solutions for features and products that aren't even desired

"but could you call it well-engineered" If it is still standing after 1000 years, I would say yes. You cannot build a bridge out of stones with bad engineering - it would collapse under its own weight. edit: does "well engineered" now means over engineered to some?

I like to tell people that all engineering is about tradeoffs.

People who engineered bridges during Roman Empire had different tradeoffs to consider than people who were building bridges in 20th century.

Standing for a thousand years is rarely an ultimate goal when engineering a bridge although it is possible that Romans planned for longer timescales than us.

If we decided to build like Romans did, there would likely be very little infrastructure and many structures would simply be impossible to construct.

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

#258

Post by doom2 »

matthewdgreen wrote: post #234
Par_Avion wrote: post #80

Oh, this makes me feel bad for Baltimore. Only bad news seem to come out of this town. Its reputation -- both domestically and internationally -- is mostly informed by The Wire, Freddie Gray/BLM, a dysfunctional city government, the 2019 ransomeware attack, the spoiled batch of J&J Covid vaccine... and now this. It's a real shame. It's a good place.

We’ve also got cherry blossoms, some good ramen and a few good breweries. Shocking lack of excellent Mexican food, however. And some world-class hospitals and universities. Don’t take TV shows so seriously.

Not a ton of Mexican food, but if you're open to other Central or South American cuisines, there are a ton of places in upper Fells Point.

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

#259

Post by Hamuko »

_heimdall wrote: post #254
Hamuko wrote: post #211

Earlier quoted context omitted.

Doesn't the US have a problem with bridges exceeding their expected service lives?

That's a common topic here, yes, though honestly I rarely hear about a bridge collapse. I don't actually remember the last time I saw news of a bridge or overpass collapse that wasn't causes by damage like this. Makes me want to find the data now. I don't actually known if our bridges are too old, poorly maintained and falling apart early, or if the whole topic is just herd mentality and politics.

>I don't actually remember the last time I saw news of a bridge or overpass collapse that wasn't causes by damage like this.

Fern Hollow Bridge Mk. II?

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

#260

Post by hgomersall »

I was wondering after watching the video whether there could be an emergency bridge closure protocol if a ship veers off its intended course. It naively looks to me like there would be sufficient time to log the course deviation and stop vehicles from entering the bridge with lights and sirens and stuff.
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