There is a really good paper with a simulation. https://gerardjoreilly.github.io/files/Journal/J6-2019_Calvi...

Yet Italy spent years trying to put Adrian Newey in jail for building an f1 car involved in a fatal crash.

Not a well-connected Italian, obviously.

> Not a well-connected Italian, obviously.

Obviously, since he isn't an Italian at all :-/

They also tried to put a bunch of earthquake scientists in jail for not predicting an earthquake.

No, they were jailed because they reassured the population that there was no risk of earthquake, when there absolutely was. That's very different.

Still ridiculous, though. Do doctors in Italy go to jail for giving false negative cancer diagnoses? Can I sue the weather man when I get struck by lightning when they said there's no chance of rain? Maybe next time the public should interpret the seismographs themselves.

Edit: It was eventually overturned [1]. Still, a shocking indictment of the court system.

1. https://www.theverge.com/2014/11/11/7193391/italy-judges-cle...

> Still ridiculous, though. Do doctors in Italy go to jail for giving false negative cancer diagnoses?

If there were strong indications of cancer and a doctor blatantly ignored it? An argument could be made that's negligence causing death.

Clearly some degree of negligence is absolutely criminal when people's lives are on the line. Maybe you don't agree where that line was drawn in this specific case, but that's not an argument that no such line exists.

Negligence means everything would have been fine if everyone involved did their duty. So I gave cases where people did their duty, got it wrong, and weren't negligent. You can imagine scenarios where they were negligent because they didn't do their duties, but I can assure you they were not since these were my imagined scenarios. In the case of these scientists who did their duty to the best of their abilities, this wasn't negligence, full stop.

Yeah don’t get involved in the Italian “justice” system. For another example, the still ongoing prosecution of Amanda Knox.

As the video states this was flagged by inspections 14 times over 7 years or so.

There's even inspection reports of one of the cross supports rusted through and disconnected, a cable taking some of the strain. At the very least the bridge should have just been closed, as unsafe.

> As the video states this was flagged by inspections 14 times over 7 years or so.

And the article starts by stating that the collapse was ‘without warning.’

Warning in this context means something obvious to the unsuspecting user that collapse is imminent. Like a building creaking or buckling minutes or hours before finally giving way.

I take that to mean there were no signs of imminent collapse, just sudden failure.

In engineering terms thats a mode of collapse, thing, not about people actually warning.

When we do design, we're generally designing things so that if it fails it does so in a way that doesn't suddenly all collapse at once, but first deforms for a while so people can get away.

Vibrations on a bridge are not normal?

I'm asking because I've been in standstil traffic (in my car) on the Lisbon "golden gate" type bridge and that thing was freaking bouncing up and down from traffic on other lanes.

Interestingly, the 25 of April Bridge in Lisbon was made by the American Bridge Company, same as the Bay Bridge, but not the Golden Gate.

And yes, it's normal. That bridge is very well maintained (there's a whole team there working daily, afaik, and I've witnessed many interventions in the past).

Now that you mention it, the diagonal braces on the piers (no idea how they're actually called) look very similar to the Bay Bridge. But to the casual observer, the number of piers and the color look more like the Golden Gate bridge, plus that's by far the better known one, so I'm not surprised it got this nickname...

I agree, and it's a very common misconception among locals that it's related to the Golden Gate bridge

Bridges do move some normally, yes. It may depend on the type of bridge though? Certainly suspension bridges do.

It's a suspension bridge. And a solid one :) Takes 6 lanes of traffic and whole trains on the bottom.

Trains cross bridges easily as they're either balanced with each half on each side, or half on and half on ground. And other time's just between these stable points. Furthermore, trains run on tracks which reduces chance of turning acceleration.

Unless it’s a floating bridge…

The thing about floating bridges is they don't need to span a waterway. The just need to link the part where getting onto the bridge then the bridge itself move to the exit section.

Floating bridges also don't necessarily need to have fixed points to load and unload. With suitable stabilisation and propulsion, they should be able to move to any number of loading and unloading points. We could have a floating bridge per train, vehicle, or any unit or set of users.

there will be a rail link across a floating bridge in seattle opening in 2025.

it was supposed to open earlier, but the contractor messed up the concrete pour and is fixing it at their own cost. but that doesn't have much to do with the fundamentals of the floating bridge itself.

Yes and no.

Railways work well in the center of bridges. One bridge that violates this principle is the Manhattan Bridge; it was built before we had fancy engineering simulations or much experience with railway suspension bridges at all, and so the lower deck is a pair of railway tracks on either side of a roadway.

This unusual design is very stressful on the bridge and has resulted in expensive rehabilitation programs.

Depends on the bridge type, I guess.

But it's true that big structures are often designed to move as a way to deal with forces. It's much better than something firm that doesn't move until it snaps.

I'm not sure you can diagnose it much from feeling vibrations if running. As an aside I don't remember it being open to pedestrians - I used to drive it occasionally.

More to the point a proper study a year before the collapse with endoscopes showed the cables were pretty rusted and dangerous https://www.lastampa.it/esteri/la-stampa-in-english/2018/08/...

The company managing it had tendered to get repairs done but they hadn't started by the time of the collapse.