At least in the links with the video now you can see that the container ship directly hits one of the two main (and in the central area only) pillars completely collapsing it.
No matter(1) the engineering there is no pretty much way to not lose the whole large middle area and left area leading to the destroyed pillar in that situation.
Such a collapse crates so much force (tension vibrations etc.) so that the collapse of the section right of the right pillar is not unreasonable.
The only question is if the impact should have made the pillar collapse.
But a loaded container ship is ... absurdly massive I mean they are like multiple high raise building (but not sky scrapers) standing squished together side by side. So the force it can apply is huge and if cargo moving in it there will be force applied to whatever it crashes into even after the initial impact.
And looking at the waves caused by impact with the base it was at least 8m high I think (depending on the container ship). So that wasn't a "slow moving" impact. And even slow moving impacts with container ships can tear apart a solid jetty.
So while the US has issues with infrastructure maintenance idk. if anything but building a many pillar bridge would have made any difference. And building a many pillar bridge might not be very viable depending on the under water landscape and water use under the main area.
EDIT: Looking at pictures with daylight where you can try to estimate the high of the ship using containers I would say the waves where handwavingly 4 containers high so ~9.5m and it also looks like the ship might have embedded half of the pillars fundament into/under itself (but it's a bit hard to tell to the angle of the picture). I think if that's the case probably the huge majority of bridge pillars of past and presence would have collapsed.
The MV Dali (IMO#9697428) is a little over 95000 GT, or ballpark-ish probably around 114000 tons loaded (and it seems to have been loaded, which would make sense on departure). If it was going even 5kn (2.6 m/s) that'd be about 300 million newton-seconds, or about 3.3 times the momentum of a large jumbo jet like a 747 shortly at cruising speed (around 560 mph). It'd still have the same momentum as said jet if it was going just 1.5kn. The ship of course is enormously more stoutly built and the force is going to be transmitted far more directly into whatever it hits vs into explosions driving mass elsewhere.
I've read that both on water and in space for that matter enormously massive objects moving very slowly messes with human perception and "common sense", it "feels like" something moving along smoothly and slowly should be stoppable or come to a stop. Enormous momentum and forces can be terrifying things.
I had a summer job once, filling trains with sugar. They weighed about 15kkg per wagon (usually 5-10 wagons per train IIRC).
One time the pulling cart broke down and we had to switch it for another, but when we took it off the rails we forgot about the "shoe" that is supposed to go between the rail and one of the wheels so it can't move downhill (it was like 1degree of slope so barely recognizable as a slope).
It started moving extremely slowly, and all of us except one tried to hold back the force of the train, which of course was imossible and dangerous. The one who did not try to push it very quickly found the "shoe" and put in place. Initially it did not seem to help at all, the train just continued moving at the same pace, tearing up asphalt with the shoe. It finally came to a stop after about 3-5m(?) which takes a fair bit of time with such low speed, and felt like forever given the situation.
The train tracks headed out into an open road, so it could have been so much worse if it were not for the only person thinking clearly in the situation (he was one of the more experienced in our group).
Also want to highlight this for another reason. At slow speeds rail and boats suffer from far less “moving” friction than road vehicles. So once off there is very little slowing them down vs cars and trucks that suffer from high rolling friction.
Grady Hillhouse of Practical Engineering recently did a great demo of this. He was able to pull his car in neutral and an empty train car on rails with roughly the same force.
I think it's actually in an earlier video, and he wasn't able to actually pull the train car due to track irregularity -- but according to calculations he should have been able to if there was a safe way to give it a bit of a nudge.
Mostly the same as it would work on a car with a brake shoe applied to the steel wheel.
The only major difference is that they often use a safety air brake system shared across an entire consist (train) that requires “charged” pressure (above atmosphere) to disengage the brake (although I think they have moved to an electronic system that now monitors air pressure in each car individually).
A friend of mine was on the light rail here downtown when it stopped unexpectedly. He was confused and walked outside only to see the train had hit a fire truck and pushed it nearly a block before it stopped. He had no idea there was even a collision inside the train.
Trains are very scary stuff even when moving at a crawl.
A 110,000 ton ship collision is something the human brain is just not going to understand intuitively.
> all of us except one tried to hold back the force of the train
This reminds me of a vivid memory I have. I’d just finished a shift cooking, and out back of our restaurant there were railroad tracks. I had a beer and smoke out there with my shift mate, and a train was rolling by. I thought it would be fun to practice jumping on the train. So I do a few passes jogging alongside it, hopping on and off. Then my buddy, standing still, reached out and grabs a rung of a ladder on one of the cars. It immediately picked him up, but he gripped harder due to being startled. He got ragdolled through the air about 10 feet from where he was initially standing.
Kids, don’t play with trains (trespassing issues aside).
> enormously massive objects moving very slowly messes with human perception and "common sense"
Yes, hence warnings to amateur boat users (e.g. on a canal boat) not to try to stop a collision with the bank using your arms or legs.
[Edit] Boats can also do things that are unintuitive if you are used to driving a car. E.g. turning round the centre of gravity when you steer rather than following the front wheels.
There are similar warnings for sailing vessels, but because the standing rigging of the ship is usually kept in high enough tension that putting your hands on a pilon to stop a collision might leave your hands vulnerable to being cut off by a mainsail's shrouds.
According to https://gcaptain.com/ship-lost-control-before-hitting-baltim... they were going 7.6kn so your figures are “optimistic” by a factor of two. I really don’t know how much an engineer could have done to stop 600M N/s - that’s just an enormous amount of energy.
Crazy! Going by the higher 7.6 kn figure mentioned elsewhere in this thread, that'd be closer to 450 million N s.
For another comparison, Wikipedia gives an estimate of "Apollo 11 launched from Earth to orbit" at 495 million N s [1]. So this is a momentum that's order-of-magnitude comparable to space launches.
I don't know what sort of speed ships travel in harbors (though I know that they are faster than they appear.) In this case, it was an ebb tide (though within an hour of the low) which might have added something to the ship's speed.
It certainly does not seem reasonable to design a bridge pillar to withstand a direct impact from a massive cargo ship.
But I guess I thought that maybe there was... typically some kind of earthen buffer around the pillar to prevent such an impact?
That's probably impractical too, I guess.
I guess I just didn't realize ~$1bn bridges were one fluky ship accident away from total collapse at any given time. I think maybe I prefer my previous state of ignorance, to be quite honest....
When Florida's Sunshine Skyway bridge was partly collapsed by a similar incident in 1980, the replacement bridge was built with a series of "structural dolphins" and concrete barriers to protect against ship strikes. You can see them in the image linked below:
I would also add those barriers seem to depend on the ship staying intact during collision. Given the immense inertia involved on the bigger ships I could just as easily see a scenario where the barrier ends up ripping through the lower hull while the rest of the ship continues forward.
> easily see a scenario where the barrier ends up ripping through the lower hull while the rest of the ship continues forward
I don’t think that is likely? My intuition is that in order to stay seaworthy ships are constructed with more integrity than that.
I don’t have any hard evidence though, just that I have looked at many ship collision/allision aftermath photos and what you describe is not a failure mode I have seen so far.
> But any preventive measure will have limits as what and how serious an impact it can deal with.
The recent grounding of a large container ship in Baltimore's harbor channel demonstrates that a sufficiently massive berm will stop any ship. What's needed is the will to do something about low-probability but catastrophic events (though large-ship collisions, groundings and fortuitously harmless steering failures are frequent enough that this should not have been dismissed as a low-probability event.)
In this case, the nearby towers supporting transmission lines across the channel seem to be better-protected against ship collisions than the piers of the bridge.
Starting from xoa's calculations above, assuming you can pack a berm with well-compacted soil enough that it can absorb 1,000 joules per cubic meter, you'd need a buffer of something like 10 meters surrounding each piling with 3 meters of depth to keep it safe from this kind of impact. That's 10 meters in every direction from the center of the support -- let's assume the support has a thickness of 0 meters for the sake of the math, and acknowledging that the gaps between structural supports on the bridge is approximately 30 meters -- the only way to protect it with earth is to make the bridge impassable by water. Of course, this would protect it from ship strikes.
Even if it takes 10 meters to get the job done (in practice, ships will not be coming at the piers perpendicularly to the channel), that is far from rendering the channel impassable.
Secondly, I believe riprap would be preferred to compacted soil (though compacted soil did a pretty good job stopping the Ever Given three years ago.)
Thirdly (and rendering the above moot), what's been done around the replacement Sunshine Skyway bridge in Tampa bay (mentioned in other posts here) shows that protection is, in fact, practical.
In view of these considerations, I'm not even going to check if, for example, xoa considered the energy absorbed by the ship (Update: in fairness, I did take a look at what xoa wrote, and I see that it is you who has introduced the figure of 1000 J/M^3.)
For an introduction to a serious engineering approach to this problem, look here:
I have to say, you guys are all calculating things without any sort of deference to the nature of the soil underneath any of these piers or abutments. Also, you're both off on your other points as well. Sunshine Skyway has in no way been tested, and there are ways to "reinforce" earthen works so that they can handle more force so that you don't necessarily need 10 m.
You guys are doing amateur engineering. Firstly we don't even know what happened here yet. Secondly we don't know the nature of the problem we'd have to solve in protecting any span that would have been at that position. (How deep is the water? How far down to bedrock? Geological nature of the soil? etc etc etc)
It seems almost impossible for us as humans to just give the professionals some time and space to work so we can see what happened. I get that. I even engage in it at times. But you guys are stating things with certainty and almost indignation? Come on fellas.
Just say your peace and admit it's just a wild ass guess that's likely to be wrong in the end like the rest of our comments.
FWIW, I think there are even more errors in my figures. That said, I wasn't trying to bunk or debunk, as much as the grandparent's comment intrigued me enough to wonder "What if earthen barrier?" -- how much earth would that take. My guess was that it would be prohibitive, and that 116,000 tonnes traveling 8.5 knots is just too much to stop. Earth obviously can, as whomever alluded to the Ever Given points out, but a lot would be required. How much? I don't know, but I was just trying to get an idea.
You're right that it's amateur. This isn't remotely what I do. To your point though, I don't have that much confidence that the Skyway bulwarks would do -- I'm sure they're more than adequate in preventing strikes from my 40' sailboat. Probably much more than that. My gut tells me they are inadequate to stop the momentum of 100k tonnes at speed, but if they did SOMEthing, perhaps that would be enough to differentiate between bridge damage and bridge collapse. I can't find any details on how it's reinforced, with what, or how deeply those reinforcements are buried, so this too is wild speculation... but I wonder if it isn't somewhat security theater. My wife is already scared of bridges, and we're Marylanders who frequent that bridge and the (much longer) bay bridge -- putting something down there to calm her nerves enough that she isn't panicking for the duration of every crossing is almost certainly worthwhile, but doesn't leave the nerds much to ponder.
There are other issues with my work, namely that the central span is over 300m in width, not 30, as I had wrongly discovered, ergo the channel is passable even with my extremely half-baked solution.
That said, the dolphin-bulwarks around the Tampa Skyway are interesting. I've sailed through similar and not known their purpose other than to observe that local waterfowl like to line up at them ahead of tidal shifts to catch the fish as they're encouraged by the currents through them.
You needn't stop the ship completely with the berm: just taking up enough energy that the bridge lives for 20 minutes after the impact would be useful.
You should look at the deisgn of old stone bridges. Their side facing up ( so towards the floods and ice) is like a wedge pointed upwards. So it's not like he bridge needs a buffer to fully stop all the forward energy. It can lift the object out of the water and maroon it there.
What's needed is the will to do something about low-probability but catastrophic events
In general I share your sentiment society could do more to insure itself against lower-probability catastrophes. But overbuilding every bridge would probably cost more than rebuilding the occasional one that's taken out when an unusual event like this occurs. Maybe in a different environment that would make sense, like a warzone (although I think even then there's more tendency to rely on redundant infrastructure and mobile, power-at-a-point defense).
I think this would be even harder. Whilst the ship has a lot of kinetic energy that needs to get dissipated, it also has a huge momentum that needs to be partly overcome to redirect it. You’d also need a material with enough structural strength to turn the ship. Materials that can crumple or deform (like huge concrete blocks or earthworks) are great at dissipating energy, but they aren’t great at deflecting things.
In smaller channels and similar it's not that uncommon to have crash barriers. For example in many Berlin channels and rivers.
And while I'm not quite sure what it is for the bridge had concrete pillars orthogonal in front of the pillars (this picture shows them well, to be clear I do NOT mean the power line isles: https://www.upi.com/News_Photos/view/upi/7191ba50f17c5a68307...). They would have stopped the ship if it would have went orthogonal to the bridge (i.e. if they mistook where the pillar where in a otherwise normal situation). Through not sure if that was the purpose of them.
I mean, yes, everybody is pointing out about the mass of the container ship, but that's actually to the point of the above question and my question. Because the ship's size and weight are obvious. Were ships this size regularly passing by or under this bridge such that this scenario was effectively bound to happen given a ship failure and/or pilot error? That's my question. I'm not familiar with port activities, so it seems weird to have basically no secondary protection for that bridge with container ships of that size operating so close that they can hit it mere minutes after some failure.
Watching this video (https://www.youtube.com/watch?v=qJNRRdha1Xk) shows that the ship was incredibly close to the bridge in the first place, even prior to the supposed failure. It's a bit bewildering to me, with my current knowledge, that this scenario wasn't envisioned prior.
That was my thought. The supports look like toothpicks relative to the ships that routinely pass through. I don't know enough about the forces involved here, but I'd like to think when they rebuild, they will add some sort of deflection capabilities around the supports that ships must past in between.
But again, I don't know what that would take to deflect a massive ship like this. In hindsight, the bridge looks terribly exposed given the persistent risk of ships passing through.
You don't need to build the bridge to an absurd strength, but it may have been insufficiently marked as a navigational hazard. Something like a few well-lit pillars 500 feet upstream in the water would have given the ship plenty of warning to change course, since a vessel travelling at 5 knots takes about a minute to go 500 feet. The total bridge length is on the order of 10,000 feet, so widening the safe area around the pillars to 500 feet would not be a significant impediment to navigation.
I've seen close-up video where you can see the ship losing electrical power twice for not-insubstantial times as it approaches the column. I suspect that was a much larger factor in the collision than anything the crew may or may not have done. Warning time doesn't mean shit if you can't steer.
seems like they should have turned left and tried to go under the middle section there instead of cranking all the way around right. I imagine they were under task saturation with the power outages though.
I think we should restrain ourselves from armchair judgements when basically no one here is a harbor pilot, let alone someone informed with what was happening in the moment in this event.
What happened will be meticulously reconstructed and everyone involved in this is going to have their lives put under a microscope for years worth of legal battles. I don't think we should rush to judgement or second guess from a position of ignorance.
I heard through the grape vine they were able to halt traffic across the bridge at the last minute. Only people actually on it when it fell were construction workers who were filling potholes at the time.
No matter(1) the engineering there is no pretty much way to not lose the whole large middle area and left area leading to the destroyed pillar in that situation.
Such a collapse crates so much force (tension vibrations etc.) so that the collapse of the section right of the right pillar is not unreasonable.
The only question is if the impact should have made the pillar collapse.
But a loaded container ship is ... absurdly massive I mean they are like multiple high raise building (but not sky scrapers) standing squished together side by side. So the force it can apply is huge and if cargo moving in it there will be force applied to whatever it crashes into even after the initial impact.
And looking at the waves caused by impact with the base it was at least 8m high I think (depending on the container ship). So that wasn't a "slow moving" impact. And even slow moving impacts with container ships can tear apart a solid jetty.
So while the US has issues with infrastructure maintenance idk. if anything but building a many pillar bridge would have made any difference. And building a many pillar bridge might not be very viable depending on the under water landscape and water use under the main area.
EDIT: Looking at pictures with daylight where you can try to estimate the high of the ship using containers I would say the waves where handwavingly 4 containers high so ~9.5m and it also looks like the ship might have embedded half of the pillars fundament into/under itself (but it's a bit hard to tell to the angle of the picture). I think if that's the case probably the huge majority of bridge pillars of past and presence would have collapsed.