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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

#201
post #153

Earlier quoted context omitted.

Thanks! So why are huge—ass container ships allowed to navigate underneath fragile public bridges with single points of failure? The not unlikely worst case is that the ship is out of control for some reason…

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.

Vertical Clearance for bridges around ports is the method used around the world. Of course, also tunnels. But building tall bridges for access is very common.

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

#202

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…

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 collapse of the section right of the right pillar is not unreasonable.

The only question is if the impact should have made the pillar collapse.

But a loaded container ship is ... absurdly massive I mean they are like multiple high raise building (but not sky scrapers) standing squished together side by side. So the force it can apply is huge and if cargo moving in it there will be force applied to whatever it crashes into even after the initial impact.

And looking at the waves caused by impact with the base it was at least 8m high I think (depending on the container ship). So that wasn't a "slow moving" impact. And even slow moving impacts with container ships can tear apart a solid jetty.

So while the US has issues with infrastructure maintenance idk. if anything but building a many pillar bridge would have made any difference. And building a many pillar bridge might not be very viable depending on the under water landscape and water use under the main area.

EDIT: Looking at pictures with daylight where you can try to estimate the high of the ship using containers I would say the waves where handwavingly 4 containers high so ~9.5m and it also looks like the ship might have embedded half of the pillars fundament into/under itself (but it's a bit hard to tell to the angle of the picture). I think if that's the case probably the huge majority of bridge pillars of past and presence would have collapsed.

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

#203
post #136

Not that it matters to anyone else, but having driven across that bridge dozens of times with my kids, this is just shocking. It’s one of the main corridors in the area. Thank god it happened in the middle of the night, though that’ll be no consolation to the families of those who may have died.

Local to the area. This was devastating news to wake up to. I don't know what's wrong with me but seeing this and knowing there were casualties made me cry. Edit: Maybe I'm just tired and need more sleep.

Hey, don't be too hard on yourself. I'm feeling it too, all the way from Medfield. It's a loss.

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

#207
post #165

Earlier quoted context omitted.

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

There already are two tunnels for I-95 and I-895 under the port.

Then why is this one a bridge? Why not go all the way and make this a tunnel too?

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

#208
post #187

Earlier quoted context omitted.

On a long enough timeline we all get rammed by a container ship. I would be interested to know some calculations with factors like: expected bridge lifetime, chance of being rammed per year, cost of making supports strong enough plus an extra safety margin to survive maximum ramming force, cost of having major commercial shipping route unusable for an extended period.

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?

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

#209
post #197
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.

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

Nothing lasts indefinitely...
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