Author Topic: Baltimore Francis Scott Key Bridge collapse  (Read 46224 times)

0 Members and 2 Guests are viewing this topic.

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 16780
  • Country: us
  • DavidH
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #25 on: March 26, 2024, 05:10:09 pm »
Even if the pilot had a medical issue, unless the ship was found to have suffered a critical systems failure, e.g. loss of both throttle and rudder control, Pilot lost his card FULL STOP, either due to responsibility for the incident or by being medically unfit.  At this point (absent such a failure) the pilot and ships' bridge officers on watch are essentially unemployable in any similar role, probably for the rest of their lives.

It looked like the ship had power failure, and then power failure of the backup system if all of that smoke was from a backup diesel generator.

https://twitter.com/CheeseEaterAnon/status/1772585380291784719
 

Online Ian.M

  • Super Contributor
  • ***
  • Posts: 12926
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #26 on: March 26, 2024, 05:28:24 pm »
I doubt that much smoke would come from a backup generator start.  Usually you get a puff of white smoke from totally unburnt fuel till it fires, then the governor kicks in and throttles back to match the load so not much black smoke.   OTOH if you suddenly throttle up a big diesel running at low speed under load to emergency full throttle, you will get *LOTS* of black smoke, especially if the engine isn't fully warmed up yet.    Whether that was with the engine initially making RPM for 8.5 knots, or was immediately after an engine restart; and whether it was a desperate attempt to get flow over the rudder, or going full astern to take way off, will no doubt come out in the NTSB report.

Meanwhile here's some preliminary analysis from a shipping industry expert:


For the landlubbers: starboard is right side, the ship hit the left pylon.
Not from the ship's point of view.  The ship was proceeding to seaward,  but the video is looking landward, so left side pylon in the video is right (starboard) side as seen from of the ship.  They'd only match if the video was from astern of the ship.

Note that COLREGs rule 9 (part) "as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable."  may not actually be to starboard of the channel centerline if no other vessel is approaching in the opposite direction.  Depending on tidal/current and wind conditions, and the ship's manoeuvring characteristics, keeping port of the centerline to allow additional room to starboard may be prudent.
« Last Edit: March 26, 2024, 06:01:29 pm by Ian.M »
 

Offline cosmicray

  • Frequent Contributor
  • **
  • Posts: 309
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #27 on: March 26, 2024, 05:57:48 pm »
The MV Dali was departing Baltimore, under it's own power, with two harbor pilots on board. Something happened to the power plant (still unclear) and the ship veered off course. Might have been the rudder, or might have been it got caught by the tide without any way to oppose it. There were 7 or 8 people on the bridge repairing potholes, and an unknown number of vehicles.

This reminds me a little of the ship collision in 1980, with the (old) Sunshine Skyway Bridge (across the entrance to Tampa Bay). That accident occurred during a strong rain squall, and the ship had one harbor pilot on board. One (of two spans) collapsed during that accident.

Prayers for everyone.
it's only funny until someone gets hurt, then it's hilarious - R. Rabbit
 

Offline BrokenYugo

  • Super Contributor
  • ***
  • Posts: 1135
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #28 on: March 26, 2024, 06:30:55 pm »
My only question is how many months/years did this ship have this problem, or some actionable sign of an issue that should have been corrected but instead was allowed to snowball. Every disaster is a long chain or large pile of bad decisions, I'd be shocked if this was the first time it acted up.

I'm sure it will come out in the report, it always does, too bad the people who need to read the reports apparently don't.
 

Offline BILLPOD

  • Frequent Contributor
  • **
  • Posts: 268
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #29 on: March 26, 2024, 07:02:55 pm »
Does Boeing have a a ship building subsidiary :scared:
 
The following users thanked this post: SiliconWizard

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 6780
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #30 on: March 26, 2024, 07:10:15 pm »
Apparently the ship radioed a MAYDAY into the port authority and the bridge was closed to traffic before the collision.  This can be seen in the footage, before the ship strikes there is a pronounced gap in traffic.

That is fantastic on the part of the bridge operators, either quick thinking or a well rehearsed safety drill.  Either way, they likely saved countless lives with this action.  Sadly the construction crew stationed on the bridge didn't seem to be aware of the danger, or if they were, they didn't get out in time.  You can see the trucks go down into the river when the collapse happens.
 
The following users thanked this post: SeanB

Offline mariush

  • Super Contributor
  • ***
  • Posts: 5092
  • Country: ro
  • .
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #31 on: March 26, 2024, 07:38:10 pm »
Yeah... they tried but couldn't get the ship to stop or turn fast enough

The guy in the video below says they black smoke is the engines running in emergency full reverse and he says the ship also dropped one anchor trying to stop the ship but the anchor was dragging along, and possibly that anchor contributed a bit to ship changing direction a bit but it was in theory a correct move in such scenarios

 

Offline floobydust

  • Super Contributor
  • ***
  • Posts: 7119
  • Country: ca
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #32 on: March 26, 2024, 07:42:41 pm »
They'd stopped traffic on the bridge but the road crew was still there I guess.
My heart goes out to the dead, crew fixing potholes at 1:30AM on the bridge. What a job to have.

The MV Dali had prior problems and crashed once at an Antwerp dock, it's 9 years old. Who knows how well maintained these container ships are.
The excessive stack smoke might be from the engine not fully supported (air pumps) when the backup generator is running?
The Bow motor really needed to work but sure didn't.
 
The following users thanked this post: tooki

Online tooki

  • Super Contributor
  • ***
  • Posts: 11869
  • Country: ch
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #33 on: March 26, 2024, 09:08:05 pm »
A friend of mine in Maryland texted me about this about an hour after it happened. Crazy.

I used to commute across that bridge daily.
 

Offline Bud

  • Super Contributor
  • ***
  • Posts: 6956
  • Country: ca
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #34 on: March 26, 2024, 09:29:09 pm »
The first thing that came to my mind watching the moment of collapse is the rightmost section of the bridge that also collapsed. Perhaps was not the best bridge design if the entire bridge collapsed because of one section was damaged.
Facebook-free life and Rigol-free shack.
 

Online guenthert

  • Frequent Contributor
  • **
  • Posts: 715
  • Country: de
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #35 on: March 26, 2024, 09:35:16 pm »
[..]
For the landlubbers: starboard is right side, the ship hit the left pylon.
Not from the ship's point of view.  The ship was proceeding to seaward,  but the video is looking landward, so left side pylon in the video is right (starboard) side as seen from of the ship.  They'd only match if the video was from astern of the ship.

And I was sure it was.  I saw only the webcam video on youtube ("lifestream") and mistook the lights in background for the port.  An aerial view clears things up: https://www.fox5dc.com/news/aerial-videos-photos-baltimore-francis-scott-key-bridge-collapse

My bad.
 

Offline nctnico

  • Super Contributor
  • ***
  • Posts: 27229
  • Country: nl
    • NCT Developments
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #36 on: March 26, 2024, 09:51:51 pm »
That brings up an interesting question: are those bridges designed to survive single-ship impacts like that?  We'd hope so, but I wonder if it's actually a requirement.

I think this comment shows a lack of understanding of the scale and proportions of the entire thing. It is pretty much impossible to build that bridge in a way that it could withstand being hit by a mass of, say, 100,000 tons, 150,000 tons etc, going at speed.  And it makes no sense, economic or otherwise.
Still, the bridge could have been constructed/designed in a way that only 1 or 2 sections collapse in case of a pylon getting damaged. Now all 4 sections of the bridge collapsed.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline bdunham7

  • Super Contributor
  • ***
  • Posts: 7950
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #37 on: March 26, 2024, 10:09:24 pm »
OTOH if you suddenly throttle up a big diesel running at low speed under load to emergency full throttle, you will get *LOTS* of black smoke, especially if the engine isn't fully warmed up yet.   

This ship has a low-speed direct-drive two-stroke engine that would have required a complete stoppage and reversal of the engine itself.  AFAIK they typically will always be fully preheated with a boiler so it wouldn't be cold, but a full-power reversal/startup would certainly generate some pretty copious smoke.  The heavy fuel they use doesn't help.  Looking at that video I think you may be right in that reversing their single screw violently changed their direction, although I certainly wonder what the rudder issue was.  I guess we'll wait for the reports to come out.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 6780
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #38 on: March 26, 2024, 10:32:08 pm »
The first thing that came to my mind watching the moment of collapse is the rightmost section of the bridge that also collapsed. Perhaps was not the best bridge design if the entire bridge collapsed because of one section was damaged.

Still, the bridge could have been constructed/designed in a way that only 1 or 2 sections collapse in case of a pylon getting damaged. Now all 4 sections of the bridge collapsed.

This type of bridge is not redundant.  A single lost section is catastrophic.  This is common to most suspension and truss bridges of this scale.  It is quite hard to imagine how you could build such redundancy into a bridge like this without fundamentally changing its design into something like a cantilever bridge which would require substantially more material.
 
The following users thanked this post: SeanB

Offline bdunham7

  • Super Contributor
  • ***
  • Posts: 7950
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #39 on: March 26, 2024, 10:41:35 pm »
I think this comment shows a lack of understanding of the scale and proportions of the entire thing. It is pretty much impossible to build that bridge in a way that it could withstand being hit by a mass of, say, 100,000 tons, 150,000 tons etc, going at speed.  And it makes no sense, economic or otherwise.

It's pretty common to have islands of large fill around the piers.  The island can be mostly underwater as it is sufficient to have the ship run aground before it gets to the bridge itself. 
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 37922
  • Country: au
    • EEVblog
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #40 on: March 26, 2024, 10:45:14 pm »
Thread from bridge designer Matt Dursh

https://twitter.com/MattDursh/status/1772605870599238112

Quote
Bridge design for vessel collision.  A🧵
The main span of the Francois Scott Key Bridge is 1300 ft. It also has 185 ft of clearance, making this a massive bridge.
This type of bridge is considered complex.
Baltimore is in for a long haul before replacement. Here is why.
We design modern bridges for ship impact, but this was not always the case.
In 1980 the Sunshine Skyway Bridge also collapsed from vessel strike.
The photo below is the original Skyway.  Similar bridges and identical failure.
The Skyway collapse changed bridge design.
The Baltimore bridge collapsed because it got hit by container ship. What failed first?
It appears the bow of the ship made contact with the vertical columns that supported the truss superstructure, causing it to have a cascade failure.
This bridge was going to fail from this event. It simply was not designed for an equivalent static force that is well over 3 million pounds.
The container ship, assuming the navigation channel is centered, veered over 500 feet off course.
Why did the whole thing fall?
The whole truss fell because this is a continuous bridge.
This means that the 3 span unit behaves as as one. If one span fails, the maximum dead loads redistributes.
This provides benefits to load resistance and is how we design modern bridges for this.
How?
Modern bridges deal with vessel collision two ways.
The first is to use a dolphin.
This is a mass of rock, sand, and steel that serves to stop the vessel before it makes contact with the bridge.
Likely the new bridge replacement will use a dolphin as one method.
The second is to design the bridge to take the vessel strike and resist the event.
This is a massive undertaking with a central focus: don't collapse.
We will see localized failures, but maintain global stability.
This load could be well over 3 million pounds.
To resist that much load to stop a vessel, we need a flexible bridge and a lot of foundations, such as piling or drilled shafts.
Typically this is more foundation needed than to simply resist earthquakes, hurricanes, and every day loads.
So where do we go from here?
Baltimore is going to be without a critical bridge for a long time.
Tampa's Skyway bridge took 7 years, but this will be done sooner, hopefully much sooner.
What needs to be done?  Well, a lot.
Can the approach spans be salvaged? 
The approach spans are likely fine.
But are they tall enough to support the new main span? Does the bridge need more vertical clearance?
Officials will nees to ask... do they fully replace the bridge in full, or attempt to reopen sooner with only the main span?
The main span is not easy to design or build, unless they make a decision to go to a smaller span bridge (less than 375ft).
But that comes with new challenges particularly with how close the piers will be to the navigation channel.
There are many things left to talk about here, but on a plane now.
I specialize in bridge design of long bridges over navigable waters.
Thanks for reading and happy to answer all questions.
 
The following users thanked this post: SeanB

Offline bdunham7

  • Super Contributor
  • ***
  • Posts: 7950
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #41 on: March 26, 2024, 10:45:59 pm »
Here's a photo of the bridge with the intended path in green and the actual path in red.  Not particularly accurate, just a rough hand drawing.  Quite the sharp turn and very unlucky.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online SiliconWizard

  • Super Contributor
  • ***
  • Posts: 14690
  • Country: fr
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #42 on: March 26, 2024, 10:51:42 pm »
Indeed, very unlucky.
 

Offline coppice

  • Super Contributor
  • ***
  • Posts: 8828
  • Country: gb
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #43 on: March 26, 2024, 10:52:16 pm »
It's pretty common to have islands of large fill around the piers.  The island can be mostly underwater as it is sufficient to have the ship run aground before it gets to the bridge itself.
All the modern big bridges have those islands around the piers. They will certainly lead to a modest sized ship running aground in a fairly harmless way. Whether they are effective against a really big container ship is another matter.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 37922
  • Country: au
    • EEVblog
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #44 on: March 26, 2024, 10:54:07 pm »
Apparently the ship radioed a MAYDAY into the port authority and the bridge was closed to traffic before the collision.  This can be seen in the footage, before the ship strikes there is a pronounced gap in traffic.
That is fantastic on the part of the bridge operators, either quick thinking or a well rehearsed safety drill.  Either way, they likely saved countless lives with this action.  Sadly the construction crew stationed on the bridge didn't seem to be aware of the danger, or if they were, they didn't get out in time.  You can see the trucks go down into the river when the collapse happens.

Yes, really fantastic effort here if that's the case.
There wouldn't be any local "bridge operator" who could run out with witches hats and signs though right? Are there electronic signs they can just switch on warning people instantly? I pressume so.
Very sad about the construction crew and anyone else caught up in this.

EDIT: Yes, they have electonic signs.
« Last Edit: March 26, 2024, 10:56:32 pm by EEVblog »
 
The following users thanked this post: boB

Offline Sal Ammoniac

  • Super Contributor
  • ***
  • Posts: 1733
  • Country: us
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #45 on: March 26, 2024, 11:07:47 pm »
That brings up an interesting question: are those bridges designed to survive single-ship impacts like that?  We'd hope so, but I wonder if it's actually a requirement.

I think this comment shows a lack of understanding of the scale and proportions of the entire thing. It is pretty much impossible to build that bridge in a way that it could withstand being hit by a mass of, say, 100,000 tons, 150,000 tons etc, going at speed.  And it makes no sense, economic or otherwise.


The San Francisco Bay Bridge was hit by a ship similar in size to the ship that hit the Key Bridge and the damage to the bridge was minimal. This was an ecological disaster due to the collision spilling 50,000 gallons of bunker oil into the bay, but no injuries on the bridge or on the ship.
"That's not even wrong" -- Wolfgang Pauli
 

Online soldar

  • Super Contributor
  • ***
  • Posts: 3439
  • Country: es
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #46 on: March 26, 2024, 11:11:13 pm »
Still, the bridge could have been constructed/designed in a way that only 1 or 2 sections collapse in case of a pylon getting damaged. Now all 4 sections of the bridge collapsed.
That makes no sense. It is a single bridge, designed and built as a whole. It is not three bridges.

In any case. If the channel span falls it makes no difference: the channel is blocked and the vehicular deck above is blocked. The result is the same: both the maritime channel and the road above are unusable.

This is a one in a billion occurrence. If the ship had lost power a minute earlier it would not have reached the bridge and if it had lost it a minute later it would have been past the bridge.

In my estimation removing the wreck of the bridge is the most urgent task so that maritime traffic can be restored. We shall see how long that takes but I am generally quite impressed by how quick the feds deal with this kind of thing.

Vehicular traffic still has a tunnel under the Bay a bit farther north and another bridge a bit to the south so, while inconvenient, it is not terribly bad.

All my posts are made with 100% recycled electrons and bare traces of grey matter.
 

Online tom66Topic starter

  • Super Contributor
  • ***
  • Posts: 6780
  • Country: gb
  • Electronics Hobbyist & FPGA/Embedded Systems EE
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #47 on: March 26, 2024, 11:12:08 pm »
Apparently the ship radioed a MAYDAY into the port authority and the bridge was closed to traffic before the collision.  This can be seen in the footage, before the ship strikes there is a pronounced gap in traffic.
That is fantastic on the part of the bridge operators, either quick thinking or a well rehearsed safety drill.  Either way, they likely saved countless lives with this action.  Sadly the construction crew stationed on the bridge didn't seem to be aware of the danger, or if they were, they didn't get out in time.  You can see the trucks go down into the river when the collapse happens.

Yes, really fantastic effort here if that's the case.
There wouldn't be any local "bridge operator" who could run out with witches hats and signs though right? Are there electronic signs they can just switch on warning people instantly? I pressume so.
Very sad about the construction crew and anyone else caught up in this.

EDIT: Yes, they have electonic signs.

Imagine being that one guy who blew past the 'STOP DO NOT ENTER' sign because "ehhh I can make it"... 

A system like this is installed in a tunnel in Sydney, not sure if anywhere else uses it for a bridge. Tunnels justify its use more often due to their greater risks (I imagine daylight vs dark tunnel makes it more difficult too).
 
The following users thanked this post: SeanB

Online EEVblog

  • Administrator
  • *****
  • Posts: 37922
  • Country: au
    • EEVblog
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #48 on: March 26, 2024, 11:16:00 pm »
They had two minutes warning:
https://www.bbc.com/news/live/world-us-canada-68663071

Quote
Ship hit bridge two minutes after mayday call
The pilot steering the Dali made a mayday call to authorities roughly two minutes before the ship collided with the bridge, Baltimore County Executive John Olszewski has said.
We also have some new details about what happened onboard, with BBC's US partner CBS News saying multiple officials confirmed the Dali crew had tried to drop an anchor to stop the ship.
It's not clear if they were able to successfully deploy the anchor.
For those wondering why tug boats were not guiding the Dali, it's because tugs are not required to escort ships under the bridge.
They are used mainly to get ships in and out of the docking station in the Port of Baltimore.
 

Online EEVblog

  • Administrator
  • *****
  • Posts: 37922
  • Country: au
    • EEVblog
Re: Baltimore Francis Scott Key Bridge collapse
« Reply #49 on: March 26, 2024, 11:19:54 pm »
Imagine being that one guy who blew past the 'STOP DO NOT ENTER' sign because "ehhh I can make it"... 
A system like this is installed in a tunnel in Sydney, not sure if anywhere else uses it for a bridge. Tunnels justify its use more often due to their greater risks (I imagine daylight vs dark tunnel makes it more difficult too).


That has been activiated quite a few times in Sydney. Tall trucks getting stuck are not that uncommon, and you don't want cars piling up in the tunnel due to exhaust. IIRC they have a height detection system now and that water barrier activiates automatically if a tall truck tries to enter.
Of course, worst case activiation would be a harbour tunnel leak.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf