Author Topic: Baltimore Francis Scott Key Bridge collapse  (Read 48211 times)

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Offline tooki

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #75 on: March 27, 2024, 06:22:19 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.
In addition to the electronic signage, there is the toll booth area on the east approach (for both directions) that could have stopped westbound traffic. But additionally, due to the roadwork being done, there were apparently traffic flaggers present. I don’t know whether they were the ones who actually stopped traffic.
 

Online soldar

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #76 on: March 27, 2024, 07:13:58 pm »
There were no dolphins.
There are, visible here in Bing maps and in my earlier photo.  Oddly they aren't visible in Google maps satellite view.
I believe they are intended more as navaids as they have lights and they are not really placed as dolphins and they are not massive enough to serve that purpose for any large ship.

They would be useless for a ship that size. I suppose they could serve to stop small speedboats or such.

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Online soldar

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #77 on: March 27, 2024, 07:19:16 pm »
Some ships have propellers on steerable pods, bow and stern, and/or bow and stern thrusters (mounted for sideways maneuvering thrust) but I understand that this ship only had one propeller (screw) and a rudder.
This YouTube channel shows time lapse videos of cruise ships arriving and departing Miami and... not a single tug.



« Last Edit: March 27, 2024, 07:26:08 pm by soldar »
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Offline tooki

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #78 on: March 27, 2024, 07:39:32 pm »
Also the size of container ships has probably increased since the bridge was designed. 
Not “probably”. A better word is “dramatically”. The Dali is a roughly 10000-TEU ship. (TEU = twenty-foot equivalent units) That’s 4x the size of the biggest container ships in existence when the Key Bridge’s construction began in 1972. And a fraction of the size of the biggest ships today, which currently top out at 24,000 TEU!
 
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Online nctnico

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #79 on: March 27, 2024, 07:42:08 pm »
Some ships have propellers on steerable pods, bow and stern, and/or bow and stern thrusters (mounted for sideways maneuvering thrust) but I understand that this ship only had one propeller (screw) and a rudder.
This YouTube channel shows time lapse videos of cruise ships arriving and departing Miami and... not a single tug.
I don't think that is a fair comparison. Cruise ships hop short distances from harbour to harbour including relatively small harbours. Freight ships OTOH travel much longer distances and are much more cost sensitive so it makes sense to equip a ship with the minimum necessary features. Keep in mind that what isn't on a ship, can't get broken  :)
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Online soldar

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #80 on: March 27, 2024, 07:47:25 pm »
I don't think that is a fair comparison. Cruise ships hop short distances from harbour to harbour including relatively small harbours. Freight ships OTOH travel much longer distances and are much more cost sensitive so it makes sense to equip a ship with the minimum necessary features. Keep in mind that what isn't on a ship, can't get broken  :)
Um... I wasn't comparing anything. Only pointing out that thrusters exist and can be used usefully.
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Online tom66Topic starter

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #81 on: March 27, 2024, 08:17:42 pm »
Also the size of container ships has probably increased since the bridge was designed. 
Not “probably”. A better word is “dramatically”. The Dali is a roughly 10000-TEU ship. (TEU = twenty-foot equivalent units) That’s 4x the size of the biggest container ships in existence when the Key Bridge’s construction began in 1972. And a fraction of the size of the biggest ships today, which currently top out at 24,000 TEU!

I am curious how much of an improvement such container ships are.  Ultimately the TEU-per-day figures are what matter for a port.

I would presume the reason they exist is they have better fuel economy, and fuel is the biggest operating expense for a ship like this.  Are they better in other ways, such as overall logistics capacity?  Or, would it be better to have more smaller ships?

If it is a case where these ships offer, for instance, 5% better fuel consumption per container-km, it could be argued that society is bearing the cost of these ships in other ways (Suez Canal blockage would not have been possible without the Ever Given for instance, 20kTEU capacity) and governments should be thinking carefully about this.
 

Online soldar

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #82 on: March 27, 2024, 08:25:02 pm »
There are, visible here in Bing maps and in my earlier photo.  Oddly they aren't visible in Google maps satellite view.

Also visible in earlier Google Earth photos
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Offline bdunham7

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #83 on: March 27, 2024, 08:31:48 pm »
I believe they are intended more as navaids as they have lights and they are not really placed as dolphins and they are not massive enough to serve that purpose for any large ship.

They would be useless for a ship that size. I suppose they could serve to stop small speedboats or such.

Hmmm, small speedboats?  The reinforced concrete part that is out of the water is over 5 meters in diameter and presumably there is much more below the water.  They are placed over 50 meters from the main bridge piers.  I'm pretty sure that would stop a medium, or even a large speedboat!  But since the Dali bypassed them entirely, we'll never know for sure.  I'm betting that if even a large cargo ship hit them at a shallow angle as they anticipated, it probably wouldn't reach the bridge piers.  But without knowing the subsea profile around those, its hard to say.
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Offline floobydust

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #84 on: March 27, 2024, 08:46:24 pm »
That would be my guess as well.
Engineering the art of compromise.
Also, safety is a relative and changing concept. In the late 19th century, in the age of sail, it was considered quite normal to lose a sailor or two on a long voyage. they climbed the rigging and accidents were common. If a sailor fell on deck he was probably dead or maimed for life. If he fell in the water the chances of recovering him were slim... even if they tried and many times they didn't because it might be considered too risky with little chance of recovering him.

Up into the 1930s building bridges and other structures the risk of death was just considered part of the job. No safety equipment and no real accident prevention. It was a very different mentality.

Today we build a tunnel and it is two tunnels plus one or two service tunnels, etc. And build with much greater safety in mind. The culture has changed. Electrical appliances and installations from 60, 80, 100 years ago were extremely dangerous by the standards of today.

It is easy to see how the mentality of safety in general has changed in developed nations. Just go to some third world countries and you still see a mentality that any money or effort expended in safety and prevention is money and effort wasted.

Safety costs money and it is good if you can pay for it. The richer we become the more safety we can afford. Which is good.

I say nope. Profit is priority #1. Engineering is not so important. Ref. Boeing.
It's a toll bridge that makes a shit ton of money $56M last year. They even sell bonds. It's a big fat cash cow. I'm sure it's paid for itself a few times over its lifetime.

Could they not afford tugboat escorts? Upgrades would not useful, no bridge can withstand a fully loaded container ship nailing it.
 

Offline .RC.

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #85 on: March 27, 2024, 11:32:20 pm »
In a previous life I had a bit to do with cargo ships.

The number that broke down or had inoperable things like bow thrusters was surprising.  It is probably why they were mostly registered in some third world country.
 
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Offline JustMeHere

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #86 on: March 27, 2024, 11:52:39 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.
In addition to the electronic signage, there is the toll booth area on the east approach (for both directions) that could have stopped westbound traffic. But additionally, due to the roadwork being done, there were apparently traffic flaggers present. I don’t know whether they were the ones who actually stopped traffic.

The police stopped the traffic.  This is well documented.  (https://www.foxnews.com/video/6349808520112).  Also there are no toll booths on this bridge (https://www.google.com/maps/place/Francis+Scott+Key+Bridge,+Maryland/@39.2298883,-76.5108951,319m/data=!3m1!1e3!4m6!3m5!1s0x89c80052ddeb3cad:0xf3fb8c8f100a3e9e!8m2!3d39.2323329!4d-76.5063164!16zL20vMDR2Njgw!5m1!1e4?entry=ttu)
 

Online SiliconWizard

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #87 on: March 28, 2024, 12:16:15 am »
I say nope. Profit is priority #1. Engineering is not so important. Ref. Boeing.
It's a toll bridge that makes a shit ton of money $56M last year. They even sell bonds. It's a big fat cash cow. I'm sure it's paid for itself a few times over its lifetime.

Those cargo ships, as .RC. also confirms, are the epitome of favoring profits over anything else, being extremely polluting and transporting cheap goods all over the world that are of dubious quality and manufactured in dubious conditions for a bottom-low cost.
So really, I don't know how we can even be surprised.
 

Offline vk6zgo

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #88 on: March 28, 2024, 12:20:38 am »
In a previous life I had a bit to do with cargo ships.

The number that broke down or had inoperable things like bow thrusters was surprising.  It is probably why they were mostly registered in some third world country.

Back in the 1950s/60s the regulation of such things in Australian ports was very strict, to the point of harshness.
Ships suspected of not meeting the safety standards, (usually back then, those registered in Panama), would undergo a "snap" inspection.

If they didn't meet the requirements, they were asked nicely to fix things, & in the meantime they could not leave the port.
The "Sheriff's Officer"* would nail (in reality, tape) a notice to the mast, officially arresting the ship.
If they still didn't fix it, the fines started to apply.

*Yes, Virginia, we do have Sheriff's, but they don't lead posses chasing "owlhoots", they are "Officers of the Court", who in turn have minions who do such things as arresting ships.
 

Offline floobydust

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #89 on: March 28, 2024, 12:22:22 am »
[...] Also there are no toll booths on this bridge [...][/url])

"All eight Maryland Transportation Authority (MDTA) facilities are all electronic (cashless). With All Electronic Tolling (AET), drivers do not stop or slow down to pay tolls. Instead, they are collected through E-ZPass, Pay-By-Plate, and Video Tolling...." source {mysteriously offline for a while now}

I wonder if this disaster is out of the woods? The ship is stuck on top of the concrete pier, full 1.5M gal of fuel, has a history of structural damage from crashing into a dock years ago. Yeah good luck there. At least it's not on fire.
It's said the ship had electrical problems for two days while docked and they're suspecting contaminated fuel as another problem.
 

Offline Someone

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #90 on: March 28, 2024, 12:47:24 am »
At least it's not on fire.
Yet/so-far.
 

Offline johansen

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #91 on: March 28, 2024, 01:41:12 am »
I would presume the reason they exist is they have better fuel economy, and fuel is the biggest operating expense for a ship like this.  Are they better in other ways, such as overall logistics capacity?  Or, would it be better to have more smaller ships?

If it is a case where these ships offer, for instance, 5% better fuel consumption per container-km, it could be argued that society is bearing the cost of these ships in other ways (Suez Canal blockage would not have been possible without the Ever Given for instance, 20kTEU capacity) and governments should be thinking carefully about this.
I don't think the ships are going to get much bigger than they are now, because at some point the lowest natural resonance frequency of the largest boats, which is already on the order of 1 second.. results in a problem where the waves can split the ship in half. bigger ship would require more steel which means your improvements in hull speed are offset by the ratio of dead to full load.

 

Offline JustMeHere

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #92 on: March 28, 2024, 02:08:28 am »
I would presume the reason they exist is they have better fuel economy, and fuel is the biggest operating expense for a ship like this.  Are they better in other ways, such as overall logistics capacity?  Or, would it be better to have more smaller ships?

If it is a case where these ships offer, for instance, 5% better fuel consumption per container-km, it could be argued that society is bearing the cost of these ships in other ways (Suez Canal blockage would not have been possible without the Ever Given for instance, 20kTEU capacity) and governments should be thinking carefully about this.
I don't think the ships are going to get much bigger than they are now, because at some point the lowest natural resonance frequency of the largest boats, which is already on the order of 1 second.. results in a problem where the waves can split the ship in half. bigger ship would require more steel which means your improvements in hull speed are offset by the ratio of dead to full load.

The size of the ships are limited by canal locks and the bridges it will encounter.   The ship class is often incorporated into the name. Ex: Panamax 366m.  400m.appears to be the current size limit.  These ships cannot enter the Panama Canal though  .
 

Offline JustMeHere

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #93 on: March 28, 2024, 02:18:57 am »
I don't think it's a question of cost vs safety.  It's a question of mass.  The more mass added to a bridge means the more additional mass that is needed to stop the bridge from collapsing under its own weight.

At some point making the bridge stronger adds more weight to the point the bridge can't be made any stronger.  (My university roommates were civil engineers, and I remember discussing this exact subject with them.)

Space flight has the same limitation.  Say it takes 2 kg of fuel to lift 1 kg of fuel. (Don't know the exact numbers, but I've heard 2-1 works.)  This is why on orbit refueling is a big step to mankind moving past Earth.
 
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Offline coppercone2

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #94 on: March 28, 2024, 02:40:50 am »
this is why the nostromo had a self destruct on it

I wonder if these ships will be robotic one day (or have a escape helicopter) and have a rapid scuttle command to sink them to save lives.
 

Offline AlfBaz

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #95 on: March 28, 2024, 02:40:57 am »
It's been 20 plus years since I worked on ships that came into our local port so treat this info with a grain of salt.
I have worked on, maintained and fault found all of the gear mentioned below

Most large vessels have three main alternators driven by 3 separate diesel engines. Each alternator is somewhere in the vicinity of 600kW and up and run on heavy fuel oil, the same as the main engine.

This fuel at room temperature is a tar like substance and is heated to decrease its viscosity. It is then run through centrifugal separators to get rid of impurities prior to being fed to the engines

Under normal electrical load conditions only one alternator powers the main switchboard.

There are 2 methods of bringing a second or third main alternator on line. Automatically or manually. Both methods are the same just controlled by hand or actuators.
The alternator to be brought on line is started, its governor is adjusted to bring the frequency of the alternators’ output up as close as possible as the one already on line.
At this stage, fine adjustments are made to the speed to get the three phases in sync using either the three old school synchro lights or simply an analogue meter whose 12 o'clock position corresponds to phase alignment.

As the needle or lights come around slowly to the synchronized position it is connected to the main bus.

At this stage, depending on what you want to do the load sharing is adjusted by increasing or decreasing the governors whilst at the same time watching the frequency.
For example if you want to bring an extra alternator online you would start the diesel, synchronize and connect it to the bus. Once connected you increase the governor speed which has the effect of increasing that generators load and decreasing the load on the existing one. If the line frequency starts getting too high then you decrease the speed of the alternator with the most load.
Most of the ships at that time didn’t have autonomous load sharing, we did start to introduce these systems onto some vessels but that’s another story.

Ships that had bow thrusters needed two geny’s on line. Namely to handle the start up current but consequently as a safety measure, should one trip off.

All of the bow thrusters I had seen had variable pitch propellers and had to be at zero pitch before they could be started. Some were DOL others employed old school resistance starters with the latter method having massive inline resistance starters or slipring motors with resistors in their rotor circuits shorted out in stages

They all have an emergency alternator that runs on normal diesel fuel that have a substantially lower kW rating and start automatically when power loss is detected on the main buss. These were also air start.

When the emergency alternator is running only a small subset of essential equipment is powered and the main generators can't be switched onto the main bus until the emergency geny is ofline

In addition to emergency AC there are large banks of single cell batteries stacked up to create an emergency 24VDC supply for navigation, radios etc.

Some vessels had more than one bank for DC supplie for other various systems. One example of this was for a vessel that had three internal gantry cranes used to move and store large 30 tonne slabs of steel with large electro magnets. A large bank of AGM batteries making up 110VDC were used in the event of loss of power to ensure a slab wouldn’t detach.

In the steering flat where the top of the rudder comes into the ship, there would be a series of hydraulic rams actuated by a large pump and indeed had a backup. The port and starboard pumps. In fact there is very little equipment on a ship that doesn’t have 2 of everything.

If that vessel had a bow thruster it would explain why all the deck lights turned on and off as with the emergency geny, only a few would have turned on but the bow thruster certainly could NOT be run off of it so they would have been attempting to put the main genys back online which presumably tripped when attempting to restart the bow thruster.

Having worked on many overseas ships they were often poorly maintained with a lot of safety stuff spragged out. Many times when surveyors were called onboard to inspect dodgy vessels, they would be laid up and barred from going to sea until rudimentary safety gear was repaired.

Speculating here, but if they were attempting to restart the bow thruster any number of issues would certainly cause the generators to trip off

edit: typo bow thruster can not be run from emergency generator
« Last Edit: March 28, 2024, 03:37:53 am by AlfBaz »
 
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Offline NiHaoMike

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #96 on: March 28, 2024, 04:51:38 am »
Given all the difficulty of having to match phases, wouldn't HVDC make more sense nowadays? And/or just stick to hydraulics for the big mechanical stuff?
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Offline AlfBaz

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #97 on: March 28, 2024, 06:00:25 am »
Most ships don't carry an electrician any more let alone EE's. So having complex systems out in the middle of the ocean needs simpler systems which facilitate farming style bodges.

I recollect one vessel coming into port where the ctrl system wouldn't, for some reason or another, allow some motor contactor to energize. I opened the front enclosure door and a lump of timber fell out as they'd jammed it in there to keep some pump motor running till they got to shore
 

Offline tooki

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #98 on: March 28, 2024, 07:44:41 am »
The police stopped the traffic.  This is well documented.  (https://www.foxnews.com/video/6349808520112).  Also there are no toll booths on this bridge (https://www.google.com/maps/place/Francis+Scott+Key+Bridge,+Maryland/@39.2298883,-76.5108951,319m/data=!3m1!1e3!4m6!3m5!1s0x89c80052ddeb3cad:0xf3fb8c8f100a3e9e!8m2!3d39.2323329!4d-76.5063164!16zL20vMDR2Njgw!5m1!1e4?entry=ttu)
I don’t do Fox News, sorry.

The various sources I saw didn’t specify exactly who was actually by the bridge directing traffic, but the construction company had stated they had traffic control staff there.


As for the toll plaza: hah, serves me right for using, um, another map app! (See attached screenshot.) Well that and the fact that I haven’t driven through there in probably a decade at least.
 

Offline tooki

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Re: Baltimore Francis Scott Key Bridge collapse
« Reply #99 on: March 28, 2024, 07:49:21 am »
At least it's not on fire.
Yet/so-far.
Why would you expect this to happen, given that no indications so far point towards anything even distantly fire-related. The Dali is now at rest, and ships at rest don’t normally just burst into flame.

The two sources of smoke initially reported by some have since been explained: the black smoke is from the engines, and the “smoke” at the point of impact is concrete dust, isn’t it?
 


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