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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

#371

Post by [deleted] »

jack_riminton wrote: post #99
irjustin wrote: post #96

Earlier quoted context omitted.

This situation is terrible, but to your specific question: Anyone can build a bridge, but it takes an engineer to barely make it stand.

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

[deleted]

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

#372

Post by KineticLensman »

bmelton wrote: post #358
KineticLensman wrote: post #317

Earlier quoted context omitted.

> enormously massive objects moving very slowly messes with human perception and "common sense" Yes, hence warnings to amateur boat users (e.g. on a canal boat) not to try to stop a collision with the bank using your arms or legs. [Edit] Boats can also do things that are unintuitive if you are used to driving a car. E.g. turning round the centre of gravity when you steer rather than following the front wheels.

There are similar warnings for sailing vessels, but because the standing rigging of the ship is usually kept in high enough tension that putting your hands on a pilon to stop a collision might leave your hands vulnerable to being cut off by a mainsail's shrouds.

Ouch! That reminded me of seeing someone get a rope burn from a line on a yacht. I always wear gloves when handling lines on a boat nowadays.

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

#374

Post by Balgair »

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.

Fucking Rocket boat...

Okay, story time. So, my brother was a law student in SF. He had a class on maritime law. They took at field trip to the Mare Island DHS office (I think) to learn more about the implementation of all the law they were learning.

So, they learned, in response to the Cosco Busan oil spill (I think), DHS decided to put in a warning system that would track all the boats in the Bay and then alert the DHS office if any of them were going to crash into Frank's Crab Shack again. Look at the trajectories, guess the time, send out an alert to the whole office. Years are spent on this system, millions of dollars, lots of studies, yadda yadda yadda.

The warning system they decided on, because this is the government and they know about lawyers, is that the whole office is going to have red flashing lights and a very loud voice come over the intra-office speakers saying 'CRASH IMMINENT". And then it'll just blare that notice until the S/W decides that the crash ain't happening anymore.

So, my brother there and they are taking the tour and the alarm goes off and ... no one does a damn thing. And he's thinking that this is really strange. And the tour guide they have looks at the group of law students and explains the above. And then the tour guide goes and says ' but they forgot about the fucking Rocket Boat'

So, in the Bay at that time, there was the Rocket Boat tour. You get on at Pier 39, you go on a tour at really high speeds, bumping your clam chowder out along the way. And to scare the tourists at the end, the pilot heads straight for Pier 39 and then turns away at just the last second. Tourists are scared, but happy, a bit wet. Everyone has a good time.

Except for the DHS office and their automated crash system. Every. Single. Time that the Rocket Boat decided to scare the tourists, the alarm system would sound.

So, since this is the government and you certainly cannot turn this millions of dollars system off now, nor can you really really be certain that the Rocket boat driver didn't actually just pass out from all the beer-only lunch he just had, the workers at the DHS office just had to endure the booming alarms and lights. Multiple times a day, nearly every day, all year long.

So, I think an automated system is a great idea. But, for the sake of all the DHS drones: Please, make the system smart enough to deal with the Rocket Boat.

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

#375

Post by boringg »

makach wrote: post #70
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…

Modern bridges are required to endure a collision. This bridge might be very old and not sufficiently maintained against current requirements.

Collision means nothing without magnitude of force.

A glancing blow is completely different from a direct hit. And the amount of Newtons behind the blow completely changes the outcomes. A small ship versus a loaded container ship is a completely different force.

I doubt many bridges would take a full speed, fully loaded container ship directly to one of their supports and survive it. Certainly the most celebrated bridges have a better chance of surviving but I doubt any second tier, lower traveled routes would.

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

#376

Post by h2odragon »

ericyd wrote: post #339
IG_Semmelweiss wrote: post #206

This port has a very large volume of car shipping. The ro-ro shipping costs are expected to go much higher as a result of this accident. If you were in the market for a car in the US east coast , act now before prices go up!

A bunch of people die and this is your response?

It sucks they died; but our life goes on.

For almost all of us, there's nothing we can do to help anyone immediately effected by this incident. Would you have everyone else stand idle in mourning and respect? For how long?

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

#377

Post by tokai »

btbuildem wrote: post #338
tokai wrote: post #285

Insane that the pylons wasn't protected by artificial islands.

If you think about this for a minute, you'll realize that what you're asking for is pretty much impossible. What would these artificial islands be made of? Sand, gravel, concrete rubble? This is a river, the constant current of the water erodes anything that resists it by staying in place. Piling up enough material to resist erosion and create a meaningful obstacle to 70000 tonnes in motion, that would significantly…

I have thought about it for hours by now, and read literature on the matter. It is definitely possible to build berms that protects a bridge from catastrophic failure in case of a ship collision, and it is widely done during modern bridge construction. Please be less sure of yourself when you clearly don't have any actual knowledge on the subject.

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

#378

Post by mannykannot »

xoa wrote: post #296
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…

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…

> If it was going even 5kn...

I don't know what sort of speed ships travel in harbors (though I know that they are faster than they appear.) In this case, it was an ebb tide (though within an hour of the low) which might have added something to the ship's speed.

https://tides.willyweather.com/md/baltimore-city/patapsco-ri...

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

#379

Post by SoftTalker »

oldgradstudent wrote: post #132
questinthrow wrote: post #23

What was the ship captain's plan here? Just ram through the bridge?

Usually, a harbor pilot guides the vessel when entering and leaving the harbor. The pilot is a former captain with a lot of local experience. https://en.wikipedia.org/wiki/Maritime_pilot [Edit: The association of Maryland Pilots even has the bridge on their homepage https://www.mdpilots.com/ ] Did the pilot screw up? Was the pilot ignore? Did the captain take over? Was there a technical fault that disabled steering?…

In most cases the pilot is there as an advisor, the captain/master is still in command of the ship.

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

#380

Post by jack_riminton »

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…

This is an excellent point, the tradeoffs are specific to the time, place and needs of the builders
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