Baltimore Bridge collapse after ship collision 125

[Tomfh]

https://amp.9news.com.au/article/b73620ea-64ab-4253-8cb0-37102418fcab

 

[KevinK2]

Latest Update: Ready To Blow Key Bridge Off MV Dali Baltimore

On saturday night, charges will be detonated to assist removal of the remaining bridge truss on the port side of the bow. Video shows installation of linear charge strips, and use of huge double shear cutting claw.

Link

Kevin Kelleher, P.E. (retired)
Internal Mechanical Eng'g Consultant
DuPont ESD Specialists

 

[IRstuff]

The demolition of the remaining bridge truss is delayed due to weather until Monday

https://apnews.com/article/maryland...d-demolition-3da84f13a5688af5cc0bdba4c922bd32

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[Alistair_Heaton]

Just as a point.. When they say charges and detonate it will be cutting charges.

The set up is a V with copper wire which gets turned into plasma that actually does the cutting. Its not a colossal bang (well it wasn't when i did it).

More of a wet fart and the metal is cut.

You could have a lifting charge to lift what's cut to separate if you thought it was required to lift and drop.

 

[Sym P. le]

The Dali barely moved, if at all, after the truss structure was detonated.

 

[JohnRBaker]

I don't think they expected it to 'move'. I think they expect it to now be free enough that it may now be possible to start moving it away from the pylon that it had crashed into.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Sym P. le]

Since the ship is still nose down, it is either firmly stuck in the mud, wedged onto the pylon foundation, or both. There is still much work to be done.

 

[dik]

Is there any idea of the costs and/or insurance claims?

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

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[Sym P. le]

WUSA9 - Youtube

"... highest charge on the bridge was set at 182 ft above the water line."

I'm not sure even knowing the number gives any sense of scale.

In the video, you can see the mooring lines move but I've yet to conclude that the ship is moving.

The stack of crushed cans resting against the bridge superstructure moves around quite a bit as the structure falls away.

 

[Nukeman948]

They filled the forward ballast tanks to ensure the ship would not move. Now that the bridge and ship are separated, they will begin pumping out the ballast to raise the ship in a controlled manner. They hope to be able to get it to a dock that can remove the remaining debris from the ship with shore cranes as that would be far easier and safer for the workers, while the floating cranes continue to clear the waters.

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[Sym P. le]

Thanks for pointing that out. I haven't been following that close.

 

[3DDave]

It still has a large amount of roadbed and pylon concrete on top of it, but now they can get close enough to lift that material as well. Per the tide charts, the tide is going out. Maybe they didn't want the ship to suddenly heave. With that chunk out of the way they will be able to come alongside to reach any other material they want to removed.

 

[Sym P. le]

"come alongside" is still very much a relative term here.

 

[Murph 9000]

The current tidal range is around 1 foot at Hawkins Point (SW end of the bridge), and maximum range is a little over 1.5 feet.

https://tidesandcurrents.noaa.gov/noaatidepredictions.html?id=8574821

I'm not saying they won't be considering it, or that it should be completely ignored, but it's quite small in the grand scheme of things.

 

[Sym P. le]

A comment from StreamTime Live chat

WBAL TV just reported that Unified command had to change plans since there were hazmat in the crashed containers, so no charges placed on the upper part of the truss

Is this relevant to anything that happened today, if so what?

I notice a few structural members were left standing nearest the cans and maybe that is what was deliberately left out of the demolition.

 

[TugboatEng]

I don't see any upwards surge of the bow whatsoever after the bridge section fell away. This indicates the ship is hard aground. There is likely flooding from the hull being gashed as it hit the bridge support. There will likely need to be some unloading of containers before the ship can be refloated.

This is something that should have been known before the bridge section was demolished. The cause of the collision should be known by now. There is zero transparency around this incident. Really makes you wonder who our government works for?

 

[JohnRBaker]

Tug, you seem to imply that the people working on this salvage effort were not aware that the ship was hard aground. OK, let me ask; if they did know that the ship was hard aground, then up to this point, what should they have done differently?

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[TugboatEng]

Nothing should have been done differently. The ship should be able to float even with a compartment or two flooded. The process involves lightening the ship until it becomes buoyant.

I was only commenting that it's annoying that zero details are being released about anything. The news stories mentioned the ship would refloat after removal of the bridge section. That didn't happen. Surely the salvors knew the ship was sunk. Where is the break in communication?

 

[Sym P. le]

I understood your post. The media is not very good. First they repeat what they hear, then they modify their position if they have too. Insight is not bothsidesism (good luck with that SpellCheck).

In a Facebook Reel of the mishap sped up 8x, it is obvious that the Dali bounced off the side of the channel prior to contacting the bridge structure. I'm not sure if that has already been mentioned. As the vessel sits, it may not be hung up on the structure foundation at all since the structure is likely vertical beneath the water line while the hull curves away from ship gunwale.

 

[TugboatEng]

One thing for everyone to consider is that the skin of a ship is very thin low strength steel. Most construction uses the equivalent of ASTM A36 steel and will be in the 0.5 to 0.75 thickness range. It doesn't take much to open the hull.

 

[SwinnyGG]

Where is the break in communication?

Why exactly would you expect a news report covering an intricate salvage operation to be accurate?

As far as I can tell they've demo'd the steel and will shortly refloat the boat. Doesn't seem any different than what's been reported.