Baltimore Bridge Collision and Collapse

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Tractionengines said:
Voith Schneider (Cycloida) Drive units are amazing for TUG maneuverability. Thrust an any direction changes almost instantly. Azimuth Drive Pods take time to turn the whole assembly. ( Standard Props are very outdated.)

https://en.m.wikipedia.org/wiki/Voith_Schneider_Propeller
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Voith units are really good for instant maneuverability, but they're not as good at converting horsepower into thrust. So (like anything in design) there are tradeoffs.
 
boatgeek said:
Hoo boy. I was wondering when tonnage was going to come up. Buckle up, this is a thrill ride. :D

First of all, let's go to the USCG Port State Information Exchange. If you want info on boats or ships that touch US waters, this is a great place to go. Here's the data for this ship:
View attachment 637377

Over on the right by where I have stuff highlighted, you'll see a bunch of tonnage numbers. The top two (not highlighted) are Convention tonnage, as measured under the International Tonnage Convention. The important thing to remember any time you see Convention Tonnage, gross tonnage, or net tonnage, is that these are measures of volume and not weight. If you see a statement that a ship is a "100,000 ton ship", that is almost certainly convention tonnage. From a basic formula and the convention gross and net tonnages, you can back out the total enclosed volume of the ship (from gross tonnage) and the enclosed cargo hold volume or passenger capacity (from net tonnage). But nobody except regulators, tax authorities, naval architects, and ship owners really care about convention tonnages. At best they're a reasonable proxy for "how big is this ship?"

The next two lines are tonnages in metric tons, meaning weight (strictly speaking, mass, but ships never leave Earth gravity, so we can call it even). Displacement is the total weight of the ship when it's loaded down to its load line. Deadweight is the total displacement minus the lightship weight, which is the weight of the ship itself. In other words, deadweight is the amount of stuff (cargo, tankage, food and stores, spare parts, etc.) that the ship is carrying. The rules for calculating lightship are moderately long, involved, and can be hairsplitting.

So if it was loaded down to its load line, it would have weighed 148,000 and change metric tons. Of course, it probably wasn't since most ships are fully loaded coming to the US (bringing in the $3 plastic crap of legend) and somewhat more lightly loaded leaving. How much lighter? :questions: We don't really know. However, lightship is around 32,000 tons, so we know it's definitely not 10,000 tons. Hazarding a guess based on where the bottom paint line is, I'd say it's likely around half loaded or around 90,000 tons.
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This is a pretty good explanation of tonnage numbers. Yes, I also get a chuckle when talking heads say a ship is x tonnes, not knowing what that number means. But if you go in and out of port often, we throw those numbers around all the time on paperwork and have them memorized in short order. Actually very important pieces of information.

My guess is that the ship was a little heavier than you estimated. Maybe 110,000 or 120,000mt displacement. But just a rough guess. Yes, we export a lot of containerized air, but they were headed on a long trip and probably filled up with fuel, plus some ballast. If I had a few more numbers I could calculate it, but not really a valuable piece of info. Just know that it was freakin' big, and no bridge on the planet is engineered to withstand that much impact force.
 
And to answer questions about age, a company like Maersk will usually build a ship like that and operate it for about 10 years. Then they sell it and perhaps charter it back for another 5-10 years if they still have need for it. After that, if it has been cared for, someone might buy it on the cheap and charter it out, or operate it another 5 years or so. Then it gets sold for scrap and run up the beach in India or somewhere and recycled into Tata motors cars. Sometimes these decisions are about financing and often a ship is owned by a bank or other financial type company.

Flag state authorities like the USCG really don't like ships older than 25 years old. That can statistically indicate poor condition and high risk of accidents. So they make it hard for companies to operate them. Older ships also get more expensive to maintain (parts, steel replacement, inefficiencies increase, new compliance issues, and so on).

Having said that, I've worked on some ships over 35 years old that were great, and 10year old ones that were relative crap. It can vary a great deal with ship type, operating company, and even flag of registry. US ships tend to be run older since they are so expensive to build.

So the Dali was approaching middle age, but looks to me to be in good shape, which is not surprising for a vessel operated by Maersk. They are considered a pretty good company, and I think is the largest in the world, or at least one of the largest.

Correction: Maersk was the charterer, but not the operator. Synergy Marine managed the vessel. But with Maersk using the ship, I would guess they don't put up with substandard operations.
 
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Getting more interesting, a dock worker said that the ship was having severe electrical problems before it left. The divers are also reporting that the ships bow is wedged in the bottom of the river.
 
rcktnut said:
Getting more interesting, a dock worker said that the ship was having severe electrical problems before it left.
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That would be ... bad for the ship management company if it bears out.
rcktnut said:
The divers are also reporting that the ships bow is wedged in the bottom of the river.
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That's expected since it ran aground. If the blackout had been five minutes earlier or later, that's all we'd be talking about.

If the NTSB's prior investigations are any guide, they'll release a "what we know now" press release a week or so after the incident. That will have details about what generators went down, what came back up before the collision, etc. It may have stuff like the electrical problems above if they are clearly borne out with evidence. The final report won't be out for a year or more, but the first cut will have most of the information we're looking for.
 
ksaves2 said:
Man they will probably have a pile of NTSB investigators on this unfortunate event. Imagine being the pilot and the Captain on the bridge to see this happen in slow-motion. Would be a nightmare. If ship maintenance was an issue, boy there will be a lot of h#ll about that.
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If the taxpayers don't pay now, we'll have a new bridge in Baltimore in approximately 15 years. Maybe. So yeah, I'd like the taxpayers to go ahead and fund restoration of port services and replacement of the bridge now, and then we'll see what we can get out of the ship's insurers later.

And please leave your political namecalling BS at the door. You know, like TRF rules say you're supposed to.
 
jderimig said:
Ship insurer's liability may be limited.

https://news.bloomberglaw.com/insur...ship-owner-limit-liability-in-bridge-collapse
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Perhaps, but I thought the limit might include the value of the cargo as well, likely to be a few dozen million bucks. In addition, they will have separate coverage for oil spill cleanup and salvage. That could pay out quite a bit more. My old company had up to 2 billion for those risks.

But yes, they won't have to cover the full bridge replacement costs. But I'm guessing that the bridge will have insurance too.

And then there is civil lawsuits where many parties can sue the operating company. That won't be too easy and would take many years to play out. The Exxon Valdiz cases took around 20 years to be settled, if I recall.

Marine insurance is very complicated, and I'm not an expert, just had a few brushes with it.
 
rcktnut said:
Getting more interesting, a dock worker said that the ship was having severe electrical problems before it left. The divers are also reporting that the ships bow is wedged in the bottom of the river.
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Dock workers would only know about lights, which is not always an indication of "severe" problems. Lights going on and off can be caused by a lot of things, most of which are not very severe.

I suggest we wait for the NTSB and USCG investigation. They are pretty good at this, and they have the data recorder from the bridge, so getting a clear picture of what happened won't be too difficult.
 
Sal reports the Port of Baltimore is losing around one hundred million dollars per day. He suggests the wreckage of the bridge could be removed from the main channel in as few as 5 days given ideal conditions. But he foresees a bigger problem in the command and coordination of so many agencies involved.

 
Sal is an amazing in-depth resource for maritime stuff like this. He does say it could be done in 5 days but later says it'll more realistically take one to three months to get the port open again.
 
cvanc said:
Sal is an amazing in-depth resource for maritime stuff like this. He does say it could be done in 5 days but later says it'll more realistically take one to three months to get the port open again.
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I think it (clearing the channel) will happen faster than that. They'll bring some barges and a crane and start grabbing that stuff up. That could be done within a week or two since there is motivation, plus government and insurance money involved. Once the channel is clear, they can take their time with the rest of the mess. That will take months. No rush at that point, since they need to design a new bridge and start lining up contracts and materials. Again, with government money to expedite it, could be done in 2-3 years as my guess. 5 on the outside. Check back here in 8 years and let me know how good a guesser I am. 😂😂
 
Capt. Eric said:
I think it (clearing the channel) will happen faster than that. They'll bring some barges and a crane and start grabbing that stuff up. That could be done within a week or two since there is motivation, plus government and insurance money involved. Once the channel is clear, they can take their time with the rest of the mess. That will take months. No rush at that point, since they need to design a new bridge and start lining up contracts and materials. Again, with government money to expedite it, could be done in 2-3 years as my guess. 5 on the outside. Check back here in 8 years and let me know how good a guesser I am. 😂😂
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I agree that clearing the channel can be done pretty quickly. A couple of weeks sounds plausible, especially given the number of USACE personnel on site (>1000!). They're motivated to get this going. They also need to clear some of the debris in order to finish the search and recovery of bodies, so that's going to get a lot of priority.

After that, the crystal grows hazy. I'd guess a year for design, maybe a little less if it's designed by a state agency (that presently has room in their schedule) without having to go out to bid by contracted structural engineers. I would guess 6-9 months to go out for construction bids and get contracts in place. The good thing is that with the amount of federal attention this is getting, we probably have a blank-ish check, so they probably won't need to go through two rounds of value engineering to reduce the cost of the project below the available budget. With contracts signed in 18-21 months, construction starts in 21-24 months.

The original bridge took 5 years to build. A roughly similar-size bridge over an active channel in Detroit is expected to take 7 years to build. That said, it's a high-visibility project so there will probably be some incentives to get it done sooner. It's amazing what a couple of tens of millions of dollars in incentives can do to get construction moving. And let's not discount the political angle. Whoever is running for president in 2028 would absolutely love to cut the ribbon in October. That would be a big lift, but it would pay political dividends for whichever party wins this November.

Boatgeek's official guess is 5-6 years before re-opening. I don't think they'll be able to make it before the 2028 election, so they'll probably do it on a more normal timeline.
 
boatgeek said:
I agree that clearing the channel can be done pretty quickly. A couple of weeks sounds plausible, especially given the number of USACE personnel on site (>1000!). They're motivated to get this going. They also need to clear some of the debris in order to finish the search and recovery of bodies, so that's going to get a lot of priority.

After that, the crystal grows hazy. I'd guess a year for design, maybe a little less if it's designed by a state agency (that presently has room in their schedule) without having to go out to bid by contracted structural engineers. I would guess 6-9 months to go out for construction bids and get contracts in place. The good thing is that with the amount of federal attention this is getting, we probably have a blank-ish check, so they probably won't need to go through two rounds of value engineering to reduce the cost of the project below the available budget. With contracts signed in 18-21 months, construction starts in 21-24 months.

The original bridge took 5 years to build. A roughly similar-size bridge over an active channel in Detroit is expected to take 7 years to build. That said, it's a high-visibility project so there will probably be some incentives to get it done sooner. It's amazing what a couple of tens of millions of dollars in incentives can do to get construction moving. And let's not discount the political angle. Whoever is running for president in 2028 would absolutely love to cut the ribbon in October. That would be a big lift, but it would pay political dividends for whichever party wins this November.

Boatgeek's official guess is 5-6 years before re-opening. I don't think they'll be able to make it before the 2028 election, so they'll probably do it on a more normal timeline.
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The reason the bridge will not take as long to rebuild as is that they should only have to replace the damaged sections not the entire bridge, most of the time spent building a bridge is on the supports not the deck structure. The steel truss cantilever structure can be built very quickly onshore barged to the location and hoisted into position in sections if needed if not steel girder structures go together very rapidly. The bridge pier struck will need to be partially or fully replaced, the others 3-4 and two sections of concrete decking may need replacement as well, all doable fairly easily since the bridge has been built once already and would need only the new sections modernized. Then again they (State of Maryland) may decide to replace the entire bridge by building a new one in that case all bets are off, but I suspect they will not go that route unless the rest of the bridge is found lacking.
 
In your back-of the-envelope musings, don't forget that bridge steel isn't an off the shelf item and the people who make it often have multi-year backlogs and waiting lists. Extra money can help here too but it only goes so far. When bridges are falling apart all over the country you need to convince someone that your emergency is more important than someone else's emergency.
 
Today I saw a meme on Facebook trying to draw some kind of conspiracy from the captain of the ship being Ukranian.

I don't see how that can even matter
 
Peartree said:
In your back-of the-envelope musings, don't forget that bridge steel isn't an off the shelf item and the people who make it often have multi-year backlogs and waiting lists. Extra money can help here too but it only goes so far. When bridges are falling apart all over the country you need to convince someone that your emergency is more important than someone else's emergency.
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My understanding has been that the common steel sections are fairly readily available with a few months’ lead time. I know that when we design barges, we use an uncommon thickness as a rulebeater and getting that custom mill run only takes a few months. That may be different if they have to use Buy America steel. If they have exceptionally heavy sections it may be different as well. And I’m open to correction by anyone who knows for sure.
 
Peartree said:
on Facebook
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There's the first and greatest clue or at least indication.
FB had a supposed glitch and kicked me off in 2015 in something they called "Malware Checkpoint" and this brings to mind something which happened in years before that.
Some way, somehow, I seemed to have an intuitive ability to smell a hoax from a block away and then massage Google the right way for it to find confirming or debunking documentation and drop it right in my lap within fractions of a second.
Said to someone named Vanessa who we were both in an incurable illness support group, that, hey, it only takes a few moments to look up whether this kind of thing is true or not before you share it. She said she did not have the time available to do that kind of thing then immediately posted what she'd just now finally accomplished after playing Farmville for the last 3 hours straight.
Say what?
Ahh, I get it ...
Entertainment is more worthy than veracity.
And be my conclusion verifiable or not ...
I decided that was the innate flavor of Facebook and at least some proportion of Facebook users, perhaps even of the entire society in which Facebook existed.
 
I would think that they will replace the bridge with a suspension bridge. That would cut down on the steel needed.
 
The visual of this wreck brings to mind a sentence in a book I'm currently re-reading,

The long wharves with their endless rows of containers and their vast rectangular gantries for dropping big boxes on to ships look from afar as though some child has got his Lego and Meccano sets mixed up.
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Page 103, Sydney, by Geoffrey Moorhouse, 1999.
 
rcktnut said:
I would think that they will replace the bridge with a suspension bridge. That would cut down on the steel needed.
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Maybe, but it would require an entirely new bridge instead of replacement of the damaged sections which would be much quicker and probably much cheaper. That would require 5-7 years as an entirely new abutement and anchoring system as well as support pillars would have to be built. The steel sections should be fairly standard grade and weights of structural H-columns iirc, heavy yes but easy to acquire cut, drill, and assemble.
 
What I can't understand is how the ship was able to hit the pylon in the first place. Every bridge I have seen over a waterway has large concrete bumpers on both sides of the supports to stop a ship or boat from hitting the bridge supports. They also have timbers on the sides of the supports. What I have seen in the pictures doesn't show bumpers. I did see a small concrete structure but it wasn't close to the support. I was also surprised that the whole bridge came down. I would have thought that only the span between the two central supports would have come down.
 
teepot said:
What I can't understand is how the ship was able to hit the pylon in the first place. Every bridge I have seen over a waterway has large concrete bumpers on both sides of the supports to stop a ship or boat from hitting the bridge supports. They also have timbers on the sides of the supports. What I have seen in the pictures doesn't show bumpers. I did see a small concrete structure but it wasn't close to the support. I was also surprised that the whole bridge came down. I would have thought that only the span between the two central supports would have come down.
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See @OverTheTop , the ship is huge I mean if you look at those boxes they are the same ones you see on the back of a semi and they are stacked 10 or 15 high…
 
teepot said:
What I can't understand is how the ship was able to hit the pylon in the first place. Every bridge I have seen over a waterway has large concrete bumpers on both sides of the supports to stop a ship or boat from hitting the bridge supports. They also have timbers on the sides of the supports. What I have seen in the pictures doesn't show bumpers. I did see a small concrete structure but it wasn't close to the support. I was also surprised that the whole bridge came down. I would have thought that only the span between the two central supports would have come down.
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The ship makes contact with its bow deck, and underwater at the bulbous section. Those will crunch and compress with all the momentum behind it. The contact underwater cannot stop the overhanging bow from reaching the bridge pillar, unless that little island, actually more like a post since the depth close to it is 30-50ft, were made about 200 feet, plus the width of the pillar, in diameter or more. That would typically be unusually large and expensive.

Timbers do nothing to stop a ship hitting something that directly. 2ft square timber is occasionally used as a rub rail on a pier, just to keep ship's steel from rubbing the concrete, but it won't stop a ship even 1/4 the size of that from crushing the wood like it wasn't even there. Note that when a ship comes alongside a dock, it is moving at about 20ft a minute or less, otherwise damages may happen to the ship and dock. It's not like a boat hitting a floating dock at your local marina.

As for the bridge, the pillar was knocked out, taking down the two sections on either side. Without those, the pillars on the other ends are out of balance since there is now only weight on one side of them, so they fail, and so on until the dominoes reached a point where the spans were lighter and the pillars closer together. At least that's what I recall from my strength of materials instructor some 37 years ago, who was a bridge designer when not teaching.
 

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