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Baltimore's Key Bridge struck by cargo ship, collapses
301–310 of 1001 posts
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#302I 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.
Seems pretty simple - sonar/lidar devices that detect dangerous ship vectors, the bridge already had gates and traffic control from some of the pictures.
Probably cheaper to do, than even the loss of one or two containers off of that container ship. Never mind the cost in human lives.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#303Earlier quoted context omitted.
Clip here, beginning at 1m23s, shows a (sped-up) edit of the ship approaching the bridge, with lights going out, on, and out again immediately prior to impact: https://yewtu.be/watch?v=Cs6PrRiIHEw&t=1m23s >
Curious, is there a specific reason you put links between ?
Carry-over from Markdown, and it appears to help HN's URL parser in some instances:
https://news.ycombinator.com/item?id=32745065>
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#304Re: Baltimore's Key Bridge struck by cargo ship, collapses
#305Earlier quoted context omitted.
Some other bridges have barriers around, but not connecting to the pylons.
Those are great for little boats like one of those superyachts. They become dominoes that hit before a boat like this: https://www.vesselfinder.com/?imo=9697428
Absolutely. 116851 long tons deadweight, which the Google info box says includes everything (busy now, so can't check in detail). That's 120,000,000 kg, so a little bit less than I guessed. Now looking at 10km/h or 6.2mi/h or 2.78m/s, that's enough to come up with a big E for E = 1/2 * m * v². The momentum p = m * v is also rather unpleasant. If the momentum was suddenly transferred into my 2,000 kg car (e.g. if the ship hit my car), I could do my work trip in about 1s, though that's only a few times times faster than the ISS (which travels at 7660 m/s).
[I'm very busy, so hopefully I didn't forget/add a few 0s by accident. Anyone feel free to correct me if I did.]
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#306Earlier quoted context omitted.
You cannot put the entire weight of the 70's safety culture to an engineer "showing off" I bet there was a much more complex and nuanced analysis which included crossing ship dimensions, budget, time to completion, available technology, composition of the local seabed etc.. Designing a bridge is proper engineering and not that easy.
Believe me, an engineering student that sees that, immediately understands the problems after taking the first science of construction lessons. You do need need the truss at all. If the truss fails (in any of the three spans), it brings down two adjacents spans. It's just a show off.
There's been at least 50 years, probably more like 60 or 70, of advances in the art (much less pedagogy) that those students have and the bridge engineer did not.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#307Earlier quoted context omitted.
Curious, is there a specific reason you put links between ?
In markdown (or at least some flavors) that is the typical way of making a hyperlink actually a link. It's equivalent to [link](link) in markdown.
Angle brackets are used for "naked" URLs & email addresses in Markdown:
https://www.markdownguide.org/basic-syntax/#urls-and-email-a...>
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#308Somehow 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…
The Bay Bridge in SF has been hit by numerous ships (as large as tankers)
The 2007 Cosco Busan incident appears to be a glancing blow. I can't find any information suggesting an analogous impact at any point.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#309Earlier quoted context omitted.
Not all bridges are this vulnerable to a single impact. This one, opened 12 years earlier, has a different style and mostly survived a cargo ship impact: https://en.wikipedia.org/wiki/Tasman_Bridge_disaster
Hobart learned its lesson. You can't drive over the bridge when heavy ships sail under it.
Yes, but Hobart is tiny so this rarely happens and relatively few people are impacted when it does.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#310Earlier quoted context omitted.
>>But I guess I thought that maybe there was... typically some kind of earthen buffer around the pillar to prevent such an impact? It does look reasonable to have such a buffer. But any preventive measure will have limits as what and how serious an impact it can deal with. In this case the ship this massive is something that is carrying ridiculous inertia, and its highly unlikely even a buffer could stop such an impa…
> But any preventive measure will have limits as what and how serious an impact it can deal with. The recent grounding of a large container ship in Baltimore's harbor channel demonstrates that a sufficiently massive berm will stop any ship. What's needed is the will to do something about low-probability but catastrophic events (though large-ship collisions, groundings and fortuitously harmless steering failures are f…
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