Container Ship Struck Key Bridge in Baltimore, Bridge has Collapsed

[smokeybandit]

I would imagine they have Chessie focusing on the debris still in the water, and have the Weeks 553 removing debris on the ship.

[BND]

5 hours ago, smokeybandit said:

They blew the rest of the bridge today. Apparently everything went according to plan and they hope to be in position to free Dali in the next couple days.

I watched it live on local DC news.  We shall see but apparently they started moving the bridge structure immediately after the demo.

[rafinmd]

11 hours ago, chengkp75 said:

Yeah, still a big slab of pavement on the bow, and even with removing the weight of the truss, the bow didn't rise any significant amount, so she is likely well and truly stuck in the bottom, and they may have to dredge around her to free her.

They purposely scheduled the demo for low tide, so there may be hope for not much more needed to free her at high tide,

 

Roy

[Ocean Boy]

2 hours ago, rafinmd said:

They purposely scheduled the demo for low tide, so there may be hope for not much more needed to free her at high tide,

 

Roy

Was that so they could try to limit the amount of uncontrolled movement as the weight fell off the ship?

[rafinmd]

5 hours ago, Ocean Boy said:

Was that so they could try to limit the amount of uncontrolled movement as the weight fell off the ship?

I think so. 

 

Roy

[Pratique]

The first NTSB report is out

https://www.ntsb.gov/investigations/Documents/DCA24MM031_PreliminaryReport 3.pdf

 

Dali had two electrical failures in port the previous day, apparently related to human error. "The first in-port blackout was caused by the mechanical blocking of the online generator’s exhaust gas stack. The second blackout in port was related to insufficient fuel pressure for the online generator."

 

The two blackouts while underway were caused by unexpected breakers tripping.

 

Fuel was not contaminated. No conclusions about why the breakers tripped while underway.

Edited May 14 by Pratique

[smokeybandit]

55 minutes ago, Pratique said:

The first NTSB report is out

https://www.ntsb.gov/investigations/Documents/DCA24MM031_PreliminaryReport 3.pdf

 

Dali had two electrical failures in port the previous day, apparently related to human error. "The first in-port blackout was caused by the mechanical blocking of the online generator’s exhaust gas stack. The second blackout in port was related to insufficient fuel pressure for the online generator."

 

The two blackouts while underway were caused by unexpected breakers tripping.

 

Fuel was not contaminated. No conclusions about why the breakers tripped while underway.

Gotta think the breakers tripping the day before played some role in them tripping that night.

[Pratique]

1 hour ago, smokeybandit said:

Gotta think the breakers tripping the day before played some role in them tripping that night.

I think it was a different pair of breakers after the crew switched over the night before, something about how the breakers had not been used for a few months. But hard to draw conclusions from this.

[chengkp75]

53 minutes ago, smokeybandit said:

Gotta think the breakers tripping the day before played some role in them tripping that night.

Nope.  The first in port blackout was caused by a mechanical blockage of the generator engine's exhaust, which would have caused the engine to slow down due to high exhaust gas pressure (potato in exhaust pipe), and when the engine slows, the frequency of the generated power drops, and when the frequency drops too low, the circuit breaker for that generator will open (which is what happened).  The second in port blackout was caused by "low fuel pressure" to the next diesel generator that came online after the first blackout.  This was caused by either someone leaving a valve closed on the engine fuel system, or a clogged fuel filter, and again, when the fuel pressure drops, the engine slows down, and the same process as the first blackout happens (low speed equals low frequency results in breaker opening).  These are totally normal safety features of the engines and their breakers, and there was no malfunction, other than human error or a blocked fuel filter.

 

The first blackout under way, was caused by two totally different circuit breakers than those that were involved in the in port blackouts.  So, the in port blackouts had nothing to do with the blackouts that caused the ship to hit the bridge.  The HR2 and LR2 breakers are designed to trip on low voltage, which is what happened when the generators tripped in port, so again, this is normal operation of the breakers.

 

Ships normally have two main power transformers, one in use and one in standby, as the Dali did.  It is common to rotate between the two transformers periodically (I usually did it once a year), as the Dali crew did when restoring power after the second in port blackout.  The breakers that tripped while the ship was heading towards the bridge, were the HR1 and LR1 breakers, which were in an open condition the entire time the ship was in port, and during the two in port blackouts, so again, not involved in the in port blackouts.

 

While I understand that this is a preliminary report, I find that it suffers from a lack of maritime experience on the part of the NTSB investigators, in that nothing is said in the reports that everything that happened during the two in port blackouts was normal operation, with the exception of human error, or possibly a clogged fuel filter (which are the only two reasons for a "low fuel pressure" alarm).

 

What I suspect is that the TR1 transformer, not having been in use for a while (undetermined at this point how long), likely developed a short, which tripped the HR1 and LR1 breakers (as it should).  My thought is that this transformer developed a short from not having it's heater on while off line (the heater keeps the windings warm and stops condensation forming, which could degrade the insulation.

 

It was 4 minutes from the time of the first blackout, and striking the pier.  The NTSB says the VDR (voyage data recorder) stopped recording when the blackout happened, but restarted recording one minute later.  The NTSB says they don't know when the emergency generator came online, but the restarting of the VDR gives that clue, within 1 minute.  The second blackout was less than two minutes after the first, and power was restored using the standby main generator, which started itself and put itself online in less than a minute, and full power was restored just over two minutes after the first blackout.  The engine crew were really jumping to get this done, and this is very good operational awareness and training.

 

Why the DG3 and DG4 breakers tripped, causing the second blackout is unknown, but my thoughts are that the engine crew were trying to rapidly restore cooling, fuel and oil to the main engine so it could be restarted, and closed too many breakers for these pumps too quickly, causing a rapid increase in power demand, and this resulted in the generators slowing (heavy load bogs a diesel down, and until the governor and turbocharger can catch up, the engine slows, and just as in the in port blackouts, this causes low frequency, and trips the generators.  The crew may also not have restarted the fuel pumps for the generators, thinking that since they were still running (but not connected to the electrical system), that the pumps were already running.  At this time, I can't say which scenario happened, but the alarm system "data dump" should show the actual timeline and events.

 

I would say that there was no forewarning of this incident, the blackouts the day prior had nothing to do with the blackouts approaching the bridge.

[Pratique]

2 hours ago, chengkp75 said:

 

I would say that there was no forewarning of this incident, the blackouts the day prior had nothing to do with the blackouts approaching the bridge.

Except that the first pair of blackouts caused them to switch over to the disused transformer, which may have failed at a most inopportune time. Swiss cheese as you say.

 

Public officials have already accused the ship as being unseaworthy after the first set of blackouts. Maybe not technically true? But difficult to explain away as pure coincidence considering the severity of the incident less than a day later.

[chengkp75]

6 hours ago, Pratique said:

Except that the first pair of blackouts caused them to switch over to the disused transformer, which may have failed at a most inopportune time. Swiss cheese as you say.

 

Public officials have already accused the ship as being unseaworthy after the first set of blackouts. Maybe not technically true? But difficult to explain away as pure coincidence considering the severity of the incident less than a day later.

But, there was no failure of any equipment, other than a possible failure of the transformer, and there is no requirement for periodic testing of the off line transformer, or for switching between on line and standby equipment.  Many systems that have say two cooling water pumps, some engineers will run one pump until it either fails, or reaches its overhaul period, and then switch to the other pump and run it until it reaches overhaul.  Other engineers will switch between pumps on a regular (like monthly) basis.  Both practices have good and bad points, but there is no requirement to do it either way.  Nothing from why the in port blackouts happened, nor  what happened, would cause either a port state inspector (USCG) nor the class society to declare the ship "unseaworthy".  And, had there not been any in port blackouts, but the Chief Engineer decided it was time to change over transformers, the underway blackouts could still have happened, with no warning. 

 

The public officials who have claimed the ship was unseaworthy, have no conception of what seaworthiness is.

[chengkp75]

There are also phrases in the NTSB report that really shouldn't be there, if they knew anything about maritime engineering, and had, at the very least USCG investigators on the board.

 

NTSB is "investigating the ship's electrical configuration".  The "configuration" of the electrical system is in accordance with SOLAS, and class rules for shipbuilding, as shown by the fact that the ship was approved by flag and class at the planning stage and during building and testing, and during subsequent annual surveys by class and by port state control in various nations.

 

"The emergency generator was not configured to power the ship".  No emergency generator, on any ship, is configured to power the ship.  The systems that an emergency generator must power are specified in SOLAS, and are basically enough to allow an evacuation of the ship, nothing more, and in fact an emergency generator is limited from powering much more than what is mandated, simply to prevent overloading of the generator.

 

The USCG and NTSB are looking into whether the crew reported the in port blackouts.  From my experience, and reading the CFR's, there is some gray area as to whether a blackout, while the ship is at the dock, and which did not happen as a result of a failure of any equipment (except the human equipment), is a reportable marine incident or not.

 

These kinds of statements, given out to a lay public, without supporting facts or context to maritime regulations, leads to a lot of things like people calling the ship unseaworthy.

 

Could the ship have been considered unseaworthy?  Perhaps, if there are other facts and conditions not mentioned.  But given the statements in the NTSB report, no, but they don't say so.

[CarnivalShips480]

If anyone is interested...

 

Here is a proposal for the new bridge. The clearance would be 230 feet, up from the old bridge's 185 foot clearance. Also, the main span would be 2230 feet, almost double what it was before.

Edited May 15 by CarnivalShips480

[Pratique]

4 hours ago, chengkp75 said:

Could the ship have been considered unseaworthy?  Perhaps, if there are other facts and conditions not mentioned.  But given the statements in the NTSB report, no, but they don't say so.

I'm an electrical/software engineer and all of what you say makes sense to me.

 

But the reality is that someone needs to be held accountable for this tragedy and it needs to be explained to the public. The public is unlikely to be satisfied with a technical explanation that nothing within reason could have been done to prevent it, even if that is true. If in the end that it all there is to say, then it seems like something else needs to be done to help prevent it from happening again. Maybe new ship design and/or bridge design. Otherwise it's like telling people in Houston that every flood is a 100-year flood. Hard to trust that it won't happen again soon.

 

And we are assuming now there was no sabotage or negligence even though criminal and civil investigations are still underway. This NTSB report is preliminary fact finding but I agree that it leaves much to be desired and makes me wonder whether the investigators really know what they are doing. Which is just going to make things worse. This report also felt rushed, I would not have expected to see it for another month or two at least.

[Pratique]

50 minutes ago, CarnivalShips480 said:

If anyone is interested...

 

Here is a proposal for the new bridge. The clearance would be 230 feet, up from the old bridge's 185 foot clearance. Also, the main span would be 2230 feet, almost double what it was before.

A cable stayed design seems like the way to go. Much more redundancy than a truss.

[smokeybandit]

5 minutes ago, Pratique said:

The public is unlikely to be satisfied with a technical explanation that nothing within reason could have been done to prevent it, even if that is true.

The public has long since lost interest in this.

[mo&fran]

The bridge pictured above has it supports in shallow water. No vessel big enough to hurt it would run aground before it got there.

[Pratique]

22 minutes ago, smokeybandit said:

The public has long since lost interest in this.

Probably more accurate to say the public is complacent. We are all paying for this though.

[Pratique]

14 hours ago, chengkp75 said:

I would say that there was no forewarning of this incident, the blackouts the day prior had nothing to do with the blackouts approaching the bridge.

Chief, one thing you have not discussed is speed. My understanding is that a ship this size needs to keep it's speed up for navigating through a narrow channel without a tug assist. In this case close to 10 knots. Which is why they didn't have enough time to recover from the blackout. Add to that the loss of steering control and it seems like a recipe for disaster - a breaker trips and the ship is adrift at 10 knots in a narrow channel.

[chengkp75]

30 minutes ago, Pratique said:

But the reality is that someone needs to be held accountable for this tragedy and it needs to be explained to the public.

What do you mean by accountable?  Will the shipowner and operator be on the hook for the lion's share of the cost?  Sure.  Just look at the Concordia, where the costs far exceeded both the hull insurance as well as the P&I insurance, and the company had to make up the difference.  Is someone "to blame" for this?  Likely not.  As I've said in many posts here about cruise ship incidents, the maritime industry has pretty much gotten out of the "blame culture", at least as far as individuals are concerned, and even corporate is not "to blame", but the SMS system the company has is not adequate.  The corporate entity will be held fiscally responsible, but unless you want to change every one of the 110,000 merchant ships currently operating, there isn't going to be anything that can prevent this from happening again, just making it less likely.  How many levels of redundancy are you going to require?

 

From my perspective, the fact that this bridge was not outfitted with adequate dolphins or fendering after Tampa's Sunshine Skyway bridge collapse is one of the glaring deficiencies.

[Charles4515]

32 minutes ago, Pratique said:

A cable stayed design seems like the way to go. Much more redundancy than a truss.

Likely the new bridge will be cable stayed. The photo is of one proposal. MDOT will be issuing a request for proposals so what they choose may or may not be the proposal in the image. 

[alfaeric]

36 minutes ago, smokeybandit said:

The public has long since lost interest in this.

Other than the people who live there and will be impacted by this for a long time. Which is appropriate since they are the ones most impacted. 

[smokeybandit]

2 minutes ago, alfaeric said:

Other than the people who live there and will be impacted by this for a long time. Which is appropriate since they are the ones most impacted. 

Sure, they want a new bridge and fast. But they've lost interest in technical details of why the Dali crashed into it.

[Pratique]

3 minutes ago, chengkp75 said:

How many levels of redundancy are you going to require?

I get it, but also not necessarily in agreement. I used to design safety systems for Disney. I once went to a conference and we spent a lot of time talking to another attendee from the Navy who was very interested in learning about how we did things so much better than they did. It blew my mind. I think there are lots of relatively simple solutions to improve fault tolerance. It sounds like an excuse to say there are too many ships so it doesn't make sense to do anything differently. Just my perspective.

[chengkp75]

2 minutes ago, Pratique said:

Chief, one thing you have not discussed is speed. My understanding is that a ship this size needs to keep it's speed up for navigating through a narrow channel without a tug assist. In this case close to 10 knots. Which is why they didn't have enough time to recover from the blackout. Add to that the loss of steering control and it seems like a recipe for disaster - a breaker trips and the ship is adrift at 10 knots in a narrow channel.

If you'll note from the NTSB report, the ship's minimum speed of "dead slow ahead" is 8.1 knots when loaded.  This means that if you want to go slower, you need to stop the propeller completely, and allow the ship to coast.  The next higher speed is "slow ahead", at 10 knots.  Not much difference between these two, and probably less than a minute in time difference during the allision.  Secondly, ship's rudders lose effectiveness at about 6 knots and below, so if going slower than dead slow, you lose the ability to steer effectively.  And, even at 8 knots, could the ship have stopped all way and backed off from the bridge piling?  Probably not.  To reverse this propeller requires stopping the engine (it is directly attached to the propeller, no gearbox or anything), administering compressed air into the engine cylinders in opposition to the ahead firing order (so the blast of air pushes down on a piston coming up) to stop the engine's rotation, then shift the fuel pumps to the astern firing order, send compressed air again to the engine in the astern direction, to get the engine rolling, and when there is enough heat in the cylinder to ignite the fuel, the engine will start turning the propeller in the astern direction.  This, even from dead slow ahead to any astern bell will take a minimum of 45-60 seconds, and then when first turning in the astern direction, you have not built up much force to counteract the inertia of the ship.