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.

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.

ETA: Thank you bmelton for owning that.

I'm not calculating anything; instead, I pointed to an article by someone who is involved in the real engineering of protecting bridges from ships.

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.