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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

#291

Post by squigz »

mhb wrote: post #264
hgomersall wrote: post #260

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.

How could the cost of this possibly be justified?

How many people would need to die for it to be justified in your eyes? Or maybe just focus on the potential loss of cargo from trucks on the bridge, if that helps you.

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

#292

Post by lukan »

onetimeuse92304 wrote: post #257
lukan wrote: post #105

Earlier quoted context omitted.

"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…

"If we decided to build like Romans did, there would likely be very little infrastructure"

Why? The romans build lots of infrastructure. Roads, sewage, irrigation, .. and they used the materials and technics of their time.

Can't we really do better today, with all our advanced technology?

Or can't we, because everything has to be cheap, cheap, cheap?

I mean, the romans used slaves. That is cheap. But we have machines.

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

#293

Post by KoftaBob »

sph wrote: post #237
KoftaBob wrote: post #205

[flagged]

Any reason you are sharing the account of the founder and majority shareholder? What use is there in sharing their Twitter, if not to drive losers to send insult DMs at them? This is utterly shameful on your part.

That's not why I shared it at all, I included his Twitter so that people can follow along in case he makes any statements, which I imagine he will.

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

#294

Post by denton-scratch »

Retric wrote: post #187
HlessClaudesman wrote: post #170

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.

> Bridges only last for roughly 50 years.

https://en.wikipedia.org/wiki/The_Iron_Bridge

Opened in 1781, still in service and perfectly safe. Of course, there are no container ships nearby. But I reckon you could sail a container ship under it, given enough water; and to damage the bridge supports, the container ship would need climbing equipment.

1781 isn't many years after the Declaration of Independence.

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

#295

Post by billpcs »

mhb wrote: post #264
hgomersall wrote: post #260

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.

How could the cost of this possibly be justified?

"We want to make the bridge safer for the users"

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

#296

Post by xoa »

dathinab wrote: post #202
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…

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 same momentum as said jet if it was going just 1.5kn. The ship of course is enormously more stoutly built and the force is going to be transmitted far more directly into whatever it hits vs into explosions driving mass elsewhere.

I've read that both on water and in space for that matter enormously massive objects moving very slowly messes with human perception and "common sense", it "feels like" something moving along smoothly and slowly should be stoppable or come to a stop. Enormous momentum and forces can be terrifying things.

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

#298

Post by philwelch »

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?

Most of the bridges I can think of in the state of Washington are much newer than that.

There are now two Tacoma Narrows Bridges. The oldest was built in 1950. The one that infamously collapsed was built in 1940. The newer bridge is from 2007. The West Seattle Bridge was closed due to damage in 2020 and reopened after repairs in 2022. It was originally built in the 1980’s after the previous bridge was hit by a ship. There are two floating bridges on I-90 east of Seattle. One of them sunk during reconstruction work in 1990 and was replaced. Theres also a new 520 floating bridge that opened in 2016. The Hood Canal Bridge (also a floating bridge) originally opened in 1961, sunk in 1979, was reopened in the 1980’s, and large parts of it were replaced in the 00’s.

The Ballard Bridge actually is over a century old! It was opened in 1917. However there was a lot of reconstruction done during the 1930’s. The Fremont Bridge is also from 1917. Both of these bridges span a ship canal that was built between 1911 and 1934. The Aurora Bridge was also built in the 1930’s.

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

#300

Post by wizerdrobe »

millzlane wrote: post #158
jxdxbx wrote: 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.

It’s called being human.

I worked next door to the church that was shot up in Charleston and felt similarly moved despite not knowing them, never having been inside the building, and not having even been a Christian at the time.

It is a bit strange at some level - not having any true connection beyond proximity but you should probably worry if you _don’t_ at least feel a little something.

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