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Baltimore's Key Bridge struck by cargo ship, collapses
361–370 of 1001 posts
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#362Earlier quoted context omitted.
How could the cost of this possibly be justified?
Why would it be expensive? Traffic lights and sirens are cheap. The Tasman bridge apparently stops traffic for all large ships https://en.m.wikipedia.org/wiki/Tasman_Bridge
And will you also be revealing the cost of stopping traffic versus the expected loss of what it prevents?
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#363This 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 do…
> Unlike the Philadelphia bridge span collapse recently, I don’t foresee this bridge being rebuilt anytime soon.
How come?
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#364Earlier quoted context omitted.
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 sta…
Also want to highlight this for another reason. At slow speeds rail and boats suffer from far less “moving” friction than road vehicles. So once off there is very little slowing them down vs cars and trucks that suffer from high rolling friction.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#365Earlier 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.
In addition to the Hazmat issue mentioned below, tunnels have a bad record when fires break out inside them. E.g. the Kaprun disaster [0] which killed 150 people, and the Gotthard Road Tunnel [1] fire, after which the use of large vehicles was constrained.
[0] https://en.wikipedia.org/wiki/Kaprun_disaster
[1] https://en.wikipedia.org/wiki/Gotthard_Road_Tunnel#2001_coll...
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#366Not 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.
Memories of the Minneapolis bridge collapse.
I lived <1 mile from it at the time it went down, and had crossed it earlier in the day on my commute.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#367Somehow 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…
This situation is terrible, but to your specific question: Anyone can build a bridge, but it takes an engineer to barely make it stand.
Why are you throwing shade at civil structural engineering?
Do all bridges we build need to be able to withstand the force of an entire shipping container bridge hitting it at high speed? What planet should an engineer think that a shipping container has managed to veer off course so badly that they hit a bridge at full speed, fully loaded? That is a sad and significant outlier event.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#368Earlier quoted context omitted.
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.
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Re: Baltimore's Key Bridge struck by cargo ship, collapses
#369Earlier quoted context omitted.
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.
How many? It depends on the opportunity cost of installing and maintaining whatever half baked thing (lights, sirens, computer vision, AI, barriers) it is OP is envisioning on how many thousands of bridges versus the frequency of issues it will prevent. This calculation is done all the time but not so much by the "if it saves only one x" crowd of clever solution proposers.
> whatever half baked thing (lights, sirens, computer vision, AI, barriers) it is OP is envisioning
Do you think OP should have produced a formal proposal with input from industry experts and detailed cost and risk mitigation figures before submitting a comment on an internet forum?
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#370Earlier 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.
> 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.
I'll raise you: https://en.wikipedia.org/wiki/Arkadiko_Bridge
But that's talking about the tail end of the bell curve not it's center.