Bridge Collapse

Jamie Hall

Two good videos...

https://www.youtube.com/watch?v=R4AuGZIhJ_c
https://www.youtube.com/watch?v=grjK6sqQyDA

both these people really know hat they are doing...

CLamb

I wonder who the ship first reported the emergency to? I'm guessing it was the Coast Guard unless there is another agency controlling the port. Did that agency then notify all the other local services?

Sal Santamaura

hot_rod said:

...80% of all the goods we use and consume arrive by ship...

Beyond the loss of life, nautical details of the event (which I know nothing about and defer to those here who are informed), disruption to land travel and cost/time to replace the bridge, this bit of what hot-rod wrote seems next most significant. It's a sad commentary on what offshoring of almost everything has done to our country. I have no magic formula for reversing it, but sincerely hope we begin to do so.

SlamDunk

I'm pretty confident that 80% of ALL goods are shipped by sea, not the just goods consumed in the US.

A better google search would be "how many ships leave US ports empty?"

Just googled that. 59% of shipping containers leave US ports empty. Huh. I cant help but think it isnt that simple.

hot_rod

SlamDunk said:

I'm pretty confident that 80% of ALL goods are shipped by sea, not the just goods consumed in the US.

A better google search would be "how many ships leave US ports empty?"

Just googled that. 59% of shipping containers leave US ports empty. Huh. I cant help but think it isnt that simple.

Sylvain

hot_rod said:

80% of all the goods we use and consume arrive by ship.

The good news is: it doesn't come by air transport.

Sylvain

JamieHall said

Second, it is common, but not universal, to have the main electric power from a shaft generator on the main engine. Some ships have separate main generators. Either way, an electrical fault will stop the main engine (a number of pumps are involved). It looked to me from the videos as though she may have managed to get the emergency generator started -- the 30 second or so initial blackout looks about right for that). That generator probably would have given them rudder control, but without the main engine running at that speed (i now understand around 8 knots -- minimum steerage) the rudder would have had little effect.

-- but even if they got power back almost instantly the main engine takes several minutes to start *(I wonder if the smoke just before she hit was an attempt to start the main engine in emergency override?). The rudder normally does not have manual backup, but normally does have dual redundant hydraulics which can be controlled locally -- but only if there is electric power for the pumps.



"the rudder would have had little effect".
Little is better than none. At 8 Kn the ship travels about 123 m in 30 seconds. That might have made a difference.

I wander how the rudder hydraulics behaves at the very moment the electricity disappear? Does the rudder keeps its position or does it make a (full) travel in one or the other direction due to transient hydraulic valves positions?

So IMHO, ships should have their auxiliary power generators running from leaving the quay until clear from the shore.

Now, a ship does not behave like a car. It is the stern which moves sideways.
Coming back on course would have needed some kind of an S curve.

Jamie Hall

The rudder locks in position when the hydraulics are stopped. Designed that way, so the system doesn't have to be running all the time at sea.

Ships are unlike in three other ways with regard to steering. First, there is a lag -- depending on the ship, it can be long -- between a rudder command and the actual motion of the rudder. Second, once the rudder is put over and takes effect, as you note the stern will start to swing opposite the rudder -- let's say left rudder, the stern will swing to the right -- and the entire ship will actually slide slightly in the direction opposite to the rudder swing (that is again, left rudder, the ship will actually slide slightly to the right, even though it is starting to point left). This has taken more than one unwary captain by surprise.

Third, however, and in this instance perhaps most important, without the propellor wash the rudder is startlingly ineffective. Most small boat "captains" are totally unaware of this, but without the propellor wash the rudder really isn't much more than a trim tab, and the response is painfully slow (and fun fact -- without the propellor wash, full rudder (usually around 35 degrees) is much less effective than 5 or 10 degrees over).

No, once those poor guys had lost power, they were toast and so was the Key bridge -- and it is much to their credit that someone on the ship's bridge had the wit to call Mayday right away. Very sharp, very cool thinking there.

One more thought -- from experience. If you are out there in your twin Yamaha 36 foot bass boat or whatever, spare a thought for the bigger or heavier (even a fishing boat, like my own old trawler was) ship. It's not that they want to hit you when you cross their bows too close -- it's that they can't do a blessed thing about it except hope that you didn't cut it too close.

Wellness

There's going to be a big challenge in underwater welding and cutting in water the experts on site say you can hardly see in. Anybody know if robots do that work on bridges now?

Intplm.

Reports last night said the largest crane on the east coast is to arrive on seen today to hopefully minimalize the amount of under water demo. So far reports are that divers are to work under water. No mention of robots so far. I would think they would use all tools available. Divers and robots as needed.

Sylvain

Jamie Hall said:

fun fact -- without the propellor wash, full rudder (usually around 35 degrees) is much less effective than 5 or 10 degrees over).

Indeed one has to turn the rudder progressively to avoid stalling of the water flow.
As far as i know, he effectivity depends on the ratio actual yaw rate of the ship / rudder angle.

SlamDunk

While still trying to wrap my head around the damage to the Key bridge, my brother reminded me of what our high school physics teacher asked decades ago: would you rather be hit by a fast moving bullet? Or a slow moving train?

Teach also said: theoretically, a really fast moving ice cube could have sunk the Titanic just as easily as the iceberg.

I guess it isnt the damage that shocks me as much as the lack of defensive measures all high school physics teachers would have calculated if asked.

From tug boats to robust fendering to limiting the size of ships from entering the harbor because the design of the bridge is a given and the momentum of being hit by a a ship of a given weight and speed, also a given, or all of the above. Anything would have been better than nothing.

The accident was so predictable and the odds where so taken for granted.

HomerJSmith

Trying to figure out what went wrong and trying to plan so that it doesn't happen again is like beating a dead horse. Nothing of substance will change in the future. That's just human nature and is why mistakes happen over and over again. Whether a ship aground in the Suez canal, East Palestine, Ohio, train derailment, or the Baltimore fiasco, the fragility of these delivery system is obvious. The Complexity Theory says it all. Which snow flake starts the avalanche? Which grain of sand falling on a pile of sand causes the pile to collapse?
You can be sure, there will be supply disruptions, long delays, and increased costs. We are teetering on the edge of a razor blade. It doesn't matter which way we fall, disaster awaits. Perhaps, it would be prudent to stock supplies you most often use, especially since cost are escalating and delay times are increasing. "Out of stock" might just be more than a disappointment.

Jamie Hall

There are two sayings n all four major fields I've been associated with which are relevant. First, the rules and training are written in blood. Second, Keep It Simple Stupid.

The second is the one most likely to be overlooked in this modern age. The tendency is to add layers of complexity and layers of control or even regulation (and I've never seen a regulation which all by itself prevented an accident yet) on everything -- but if the fundamentals are not correct, that will only make things more prone to failure and -- often -- catastrophe.

ChrisJ

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

SlamDunk

Beating a dead horse? I dont thinks so. That's like saying the hartford loop is a waste of pipe or a LWCO isn't necessary. This was predictable, if the powers that be wanted to predict it, and is preventable in the future. Just watch the lawyers argue it. I'll bet there will be substantial changes. It just required people to be killed and a local economy to be wrecked.

As far as stocking up because of this, there are many ports that can load and off load ships.

EdTheHeaterMan

Trying to figure out what went wrong and trying to plan so that it doesn't happen again is like beating a dead horse.

I disagree, There are these people called underwriters that look at what insurance claims were paid over a time period. Then they sit down and talk about it. They say stuff like "How do we keep this from happening in the future?" Some come up with good ideas (like the boiler relief valve). Then they look at the cost of implementing the fix weighed against the cost of insuring against the problem. Then they make recommendations. Then the good ideas are made into Law or Code or Regulations or Recommendations, depending on the severity of the loss. It is all part of the economics of doing business in the world.

What never works is when a politician thinks that making a law based on something they know nothing about, is going to have any effect. Case in point: https://forum.heatinghelp.com/discussion/196737/nyc-council-bill-being-drafted-for-radiator-inspection. That law won't resolve anything, and will never find a defective radiator pipe, if that is even what caused that tragedy in the first place.

Jamie Hall

ChrisJ said:

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

Actually, @ChrisJ , there is a defensive measure which more recently constructed bridges use: basically an artificial island around the piers (the replacement Sunshine Skyway uses this, as do some other bridges in similar situations). The idea being -- quite correctly -- that running aground on such a thing will be quite effective in slowing and stopping even bigger ships.

Sadly, this could have been done for the Francis Scott Key bridge. I imagine that cost factors -- though relatively speaking not that great -- scuppered the idea. This is, after all, a government/highway department bridge. As it was, there was no -- repeat NO -- defensive structure around the piers. None. Not even an old tire.

EBEBRATT-Ed

The bridge has been there since the early 70s. So it's been over 50 years, and I am assuming it has never been hit (or at least not hit by anything big enough to take it down)


How much protection do you want? How much would it cost?

Should we stop getting on airplanes? Everything has some risk.

We have fossil fuels and electricity in our houses should we do away with that?

That's why they have something called insurance.

When the risk is big enough protection will be added. And it's not free.

KC_Jones

Jamie Hall said:

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

Actually, @ChrisJ , there is a defensive measure which more recently constructed bridges use: basically an artificial island around the piers (the replacement Sunshine Skyway uses this, as do some other bridges in similar situations). The idea being -- quite correctly -- that running aground on such a thing will be quite effective in slowing and stopping even bigger ships. Sadly, this could have been done for the Francis Scott Key bridge. I imagine that cost factors -- though relatively speaking not that great -- scuppered the idea. This is, after all, a government/highway department bridge. As it was, there was no -- repeat NO -- defensive structure around the piers. None. Not even an old tire.

You might want to read up on the USS Missouri grounding in 1950, took half a mile to stop the Missouri, with the engines not running, and the ship digging through the bottom the whole way. When it stopped the bow was a full 10’ higher than it was if the ship was still floating. The Missouri is half the loaded weight of the container ship that hit the key bridge. Let me repeat that, a fully loaded battleship is half the loaded weight of that container ship.

Running aground isn’t stopping the ship, might make people feel good to build it, but they know it’s not stopping a ship. It’s intended for glancing blows to redirect away from the bridge and hopefully prevent a direct hit. Stopping it isn’t in the cards, it’s just too much inertia. I’ve run aground in just regular boats, and they barely stop that fast, plenty of YouTube videos showing that happening.

Also you are incorrect about lack of protection. There are 4 dolphins around the bridge, quite clearly seen in aerial photography. Obviously not enough, or poor placement, but they are there. And again, if you look at any bridge protection, they are not intended to stop a ship, they are there to give some insurance the ship will go through the opening and not take the bridge out. Protection is not stopping.

Here is a picture showing the dolphins.

pecmsg

ChrisJ said:

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

Depending on the amount of cargo upwards of 250,000,000 - Tons! Yes 250 Million Tons.

ChrisJ

pecmsg said:

ChrisJ said:

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

Depending on the amount of cargo upwards of 250,000,000 - Tons! Yes 250 Million Tons.

250 million tons?

dko

The Dali (the ship in question) is a Neopanamax container ship with an overall length of 984 ft, beam of 158 ft, moulded depth of 81 ft, and summer draft of 49 ft. Her gross and net tonnages are 91,128 and 52,150, respectively, and her deadweight tonnage is 116,851 tonnes. Her container capacity is 9,971 twenty-foot equivalent units

Jamie Hall

pecmsg said:

ChrisJ said:

What defensive measures are you going to use against 99,000 tons moving at 8 knots?


Actually I think that's wrong.

How much does that ship weigh empty and how much can it carry?

Depending on the amount of cargo upwards of 250,000,000 - Tons! Yes 250 Million Tons.

Oh dear me no. Off by a factor of 1,000...

For @KC_Jones . I'm well acquainted with the grounding of USS Missouri. Actually, she managed it twice, but the one to which you are referring was in the Chesapeake Bay. There is a critical difference between that incident and striking a defensive barrier around a pier: the material and the slope. In the case of the Missouri, the material was bay mud -- which is very soft and "squoshy". It's also remarkably level. As you note, Missouri travelled half a mile for a rise of only about 10 feet in that incident. You can touch bottom in that stuff and half the time not even know it, until you look at your wake. A defensive barrier island, however, is not level. It is composed of rip rap, each particle -- if you can call it hat -- weighs several hundred to a thousand tons, and the particles interlock. The slope usually is 1 foot rise for 2 feet of run. Your bow will not ride up on it, or to the extent it crumples and does, it will be raised well out of the water. It WILL stop you.

A much better comparison for the power of an embankment to stop a ship is the incident to MV Evergiven a couple of years ago in the Suez Canal. She was travelling at about the same speed as the MV Dali -- and was stopped remarkably effectively in a matter of tens of feet -- in sand, not rip-rap.

Also on running aground with a small boat. Do try it someday, but not on a sandbar. Try it on a breakwater, which is comparable to a defensive barrier. Be surprised how fast you stop. I have watched intrepid mariners do that, and even fished a few out of the water afterwards.

I get a large chuckle over the picture posted by @KC_Jones of the protective dolphins. Yes, indeed, they are there -- around the power line towers. Right. And, in fact, had MV Dali sheered off towards one of those poles, they would have caught and deflected her. There were no protective dolphins or anything else around the bridge piers. Compliments to the power company for recognizing the threat, and doing something about it.

Zman

There is a great program on engineering failures by Stephan Ressling. In episode 6 they review an identical failure of the Skyway Bridge on Tampa in 1980. Modern engineering practices now require stiffer standards including barriers before the bridge to protect the abutments. https://www.amazon.com/Epic-Engineering-Failures-Lessons-Teach/dp/B0B7DRCVT3

CLamb

Here's a surprising good technical article on the force of the collision. https://www.nytimes.com/interactive/2024/03/28/upshot/baltimore-bridge-ship-force.html From looking at the damage on the ship it seems it did not hit the bridge head-on but on the starboard side of the bow.

Jamie Hall

CLamb said:

Here's a surprising good technical article on the force of the collision. https://www.nytimes.com/interactive/2024/03/28/upshot/baltimore-bridge-ship-force.html From looking at the damage on the ship it seems it did not hit the bridge head-on but on the starboard side of the bow.

correct -- and not all that hard, either. The bow flare just leaned on the column.
Nor is her hull damaged much below the waterline. Heave the bits and pieces off her, take her to dry dock, a few days welding and you're good to go.

SlamDunk

@EBEBRATT-Ed
How much protection do you want? How much would it cost?
I would like the protection to meet the risk even if it means banning these boats from some harbors. The cost of added protection would have cost less than what the clean up and bridge replacement will cost. It would have cost less the the economic losses Baltimore may experience.

Should we stop getting on airplanes? Everything has some risk.
There is a famous saying in aviation, and it applies to boats:

Aviation in itself is not inherently dangerous. But to an even greater degree than the sea, it is terribly unforgiving of any carelessness, incapacity or neglect.

That's why they have something called insurance.
Insurance wont arrive in time to provide for the surviving families or port workers whose pay checks will stop coming in for the next few months-years.

Jamie Hall

Your first point, @SlamDunk -- cost. Yes, it would have cost less, probably a lot less, to retrofit adequate protection for those piers. But... when have you ever seen a government entity take proactive risk protection for their own assets? It just doesn't happen.

You could ban large ships from Baltimore harbour, true. That would protect the unprotected assets. The ships would just go somewhere else where they were welcome -- and there are ample places to go on the east coast. Baltimore has enough problems without relegating it to a whistle stop on the northeast corridor.

On risk -- the highest transportation risk we (and most countries!) face is on our roads, both to life and limb of ordinary citizens, and in terms of catastrophic accidents and hazardous waste problems. All other modes are far safer. Trouble is, traffic accidents don't make headlines and clicks unless kids are involved, and all other modes do.

Insurance? Whose insurance? Unless one is going to be able to prove gross negligence on the part of the crew or shipowners (and I'm sure the lawyers will try), it can be very hard to overcome the strict liability limits which maritime law imposes -- and which are there for very good reasons. And, if you are paying attention to the news, the Port is reopening in the next few days with an alternate channel suitable for smaller ships. The only reason the main channel may take a while to reopen isn't technical -- it is bureaucracy. And who's fault is that?

SlamDunk

@Jamie Hall The lawyers and owners are already hard at work. $39M set aside for the victims' families and $43M for damage. $43M is the value of the boat after the wreck....So it begins.