I am not sure what conclusion can we draw from, as you said, two very rare incidents over a long period of time.

Reminds me of when Malaysian airlines crashed two planes in a short period of time. It was a good time to get cheap flights from Europe to south east Asia as long as you can withstand relatives thinking you are literally going to die in their third crash.

Spain basically does not do the required maintenance:

https://www.reuters.com/world/spains-deadly-rail-accidents-p...

After reading Shogun, Cryptonomicon and watching plenty anime and documents about Japan (including Japanese rail system - still using the "pointing and naming" method I've learned from them) I would risk saying that Japanese do literally everything differently.

> And that's in a country with a much larger population and much higher passenger count per year.

These are actually points making the Japanese system easier to maintain. Because of smaller surface area it’s much denser.

They are two very different accidents: The second was insufficient/poor maintenance: Supposedly the train that checks for this had passed 2 months before, and someone will have to wonder whether it's just not passing often enough, or if the inspections are just poor in general.

The first was purely a matter of not upgrading the signaling in a very low speed section: The crash could have happened with regional trains too. Every engineer knew that it was unsafe and one distraction was enough to get someone killed, but Spain is still well in the middle of track expansion, so it's all the horrors of politicking. Unless you have a crash, not upgrading those signals costs nothing, but, say, the very expensive connection to Asturias was worth a lot, so iffy tradeoffs were made.

Hopefully better engineering-driven tradeoffs are made regarding track maintenance, but hey, this is Spain, not a place where we are good at efficient, reliable safety processes: See the failures in Valencia for the DANA, where the chain between the meteorologists seeing a risk that led to recommending evacuation, and the actual order of evacuation was so slow, so we ended up with 229 deaths.

A component here is the highly unfortunate timing of two trains crossing one another as one of the trains derailed. Both trains look like rigid HSRs, and usually when these derails they stay very stable and rarely have fatalities.

Japanese rails are all built on commuter style architectures and the tracks are generally owned by its users. So train operators are strongly incentivized to keep them in good shape.

Also, Far East right now is also massively cash poor yet labor rich relative to the rest of the world. Everything is crazy undervalued and there are clear gaps between amounts of money changing hands vs work being done. Skilled-labor-intensive tasks are going to be much easier when cheap skilled labor is just perpetually available.

My understanding is that Shinkansen that is high speed rail in Japan is grade separated system. That is tracks are only used by high speed rail. In Europe generally tracks are shared outside few specific links.

This means that Shinkansen tracks are designed and build to much higher standard.

Track maintenance?

Perhaps there are less FSB agents blowing up sections of track with shaped charges in Japan.

Different soil? Different climate/weather patterns.

Japan having to build to earthquake standards, so being more robust overall? Or to specific failure modes, at least.

> What do they do differently?

Accountability.

> Santiago de Compostela derailment

Hey that infrastructure looks perfectly fine and new, ahhh ok... they were going 180kmh where the speed limit was 80kmh..

> While these events are statistically very rare

These events happening 4 times in 3 days are statistically nonexistent. Even less existent is them starting to happen right on the day before a major politician in Spain visits Israel to talk about buying Israeli security and monitoring systems.

Higher passenger count could imply ability to pass higher maintenance budgets?

I think even more important is the seismic activity in Japan asa risk factor here

Could weather or some other geographic/similar aspect be a factor?

Yeah. Japan really has better quality standards here overall.

Now - Japanese mentality is strange to me, but the quality standards and thought process, are convincing.

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Japan has a culture of perfection.

> I wonder how common it is for train tracks to fracture?

That entirely depends on which class of tracks we're talking about. And on top of that, remember that Europe is at war with Russia, railway sabotage has been attributed to Russia already in Poland [1] - and if you ask me, I don't believe for a single goddamn second that "cable thieves" were the cause behind the infamous 2022 attack on Germany's railways [2] either.

> And what systems are in place to actually detect this.

In Germany, dedicated railway cars called "RAILab" [3] that can measure track performance at up to 200 km/h perform the bulk of the work. In addition, each piece of infrastructure has something called an "Anlagenverantwortlicher", a person responsible for it - and that person has to walk each piece of infrastructure every two years at the very least, sections that have shown to be problematic get walked sometimes weekly.

[1] https://www.bbc.com/news/articles/c4gknv8nxlzo

[2] https://en.wikipedia.org/wiki/October_2022_German_railway_at...

[3] https://de.wikipedia.org/wiki/RAILab

In November, a bigger missing part of a train track was due to sabotage: https://www.bbc.com/news/articles/cp85g86x0zgo

Rare, but not unheard of. See for example the Hatfield disaster in 2000, or the 2021 Ghotki rail crash.

Most railways regularly inspect their tracks to detect issues before they turn into a disaster. The big question here will be: why wasn't this caught earlier?

Fractures could happen with ground shifting - perhaps recent flooding could have contributed

Nice find. The gap in the Spanish track is massive. I don’t know enough to speculate on technical reasons but it seems quite odd.

> I wonder how common it is for train tracks to fracture?

very

> And what systems are in place to actually detect this.

track circuit detection would pick up most cases I would have thought

CWT is laid in such a way that it has net zero stress in a "neutral" temperature, which naturally depends on the climate. Both extreme heat and extreme cold can cause damage, buckling and fracturing/embrittlement respectively, and choosing the neutral temperature is balancing act. But even if completely cut, track cannot shrink longitudinally much at all, it's the job of the sleepers and the ballast to keep it anchored in place. And if the track is laid on a concrete slab rather than ballast, it isn't moving anywhere.

Fun fact: the reason modern concrete or composite sleepers (e.g. [1]) have a slightly concave profile is to better resist lateral forces (i.e. buckling) than traditional straight-profile wooden sleepers.

[1] https://www.romicgroup.com/permanent-way/concrete-railway-sl...

It would require a very high speed camera, and a floodlight, which may be impractical.

More simply, you measure the impact for dangerous forces. No need to overcook it.

Too much processing. Accelerometer or even a microphone would do the job.

5!

An Asturias Circanías train collided with debris from a collapsed tunnel wall on Thursday afternoon in Olloniego. No injured though

A new mode for fluke meters is born: the train conductor

it is possible, track signals can be triggered by shorting between two rails for example.

Measurement trains filled with cameras and LIDAR

For example, in the U.K.:

https://en.wikipedia.org/wiki/New_Measurement_Train

There are special trains with measurement equipment on board, but yes, it sounds to me like every train should be equipped with some basic sensors for anomaly detection.

AFAIK, one technique for monitoring cracks uses ultrasonic sensors. They send sound waves through the rails and detect cracks by analyzing reflected waves.

You can look at the Wikipedia page on railway defect dectectors [0].

Under "rail break monitors" it mentions both electrical continuity and time-domain reflectometry can be used, and are most frequently used on high-speed tracks.

In addition, there are vast array of other detectors using acoustic sensors, strain gauges, accelerometers, cameras in the visible and infrared spectrum or laser measurement, that potentially could have detected an anomaly (i.e. damage to the wheels of other trains before the incident).

[0]: https://en.wikipedia.org/w/index.php?title=Defect_detector

Wheel impacts are the main way. But hardware can be bulky and trains can be surprisingly cramped.

We squeezed some track condition monitoring hardware into some locos but it was single-driver operations locations and we cannibalised some of the room that would have otherwise been occupied by the second driver.

Wheel Impact Load Detector.

It measures vertical forces in kips - (kilo-pounds-force, 1 KIP = 1,000 lbs)

They have these in the USA.

TFA indicates a 40cm gap — huge!

No, the claim is that the broken rail was the new one but it happened at the transition from old to new.

Got a link?

And how does it accord with the many statements made early on about the track being renewed recently?

I think the physics of the situation don't make a barrier feasible: a derailed train going >100 mph is going to transfer a lot of energy to any kind of barrier it impacts, which in turn might exacerbate the situation (by spreading debris).

I think these kinds of accidents are largely mitigated by rail defect monitoring. I know rails in the US are equipped with defect detectors for passing trains; I'm surprised that a similar system doesn't exist for the rails themselves. Or more likely, one does exist and the outcome of this tragedy will be a lesson about operational failures.

I’d rather they spent the money ensuring no trains ever left their tracks rather than halving the destruction if they do.

There was a switchover which made the derailed cars of the first train move into the track of the second one, you can't have a wall there anyway.

Pure economics. In Minneapolis the railroad demanded a crash wall to separate the light rail trains from their trains. It runs 1 mile and somehow cost nearly $100 million. This is a 5x increase from the original estimate but still $20 million for a 1 mile wall is a heck of a lot of money

The 20-ton bogie was flung 300m. What do you expect the weight of a whole car to do to such a wall?

You happened to have an opposing train at exactly the point where the train derailed.

That's simply really, really rare bad luck.

Practically anything you can think of is going to be a more effective use of safety resources than trying to contain a derailing high-speed train.

Thank about the change in airflow. The train would use more energy because of having to push air that is trapped by the barrier

Also the issues other comments described, including that any fault in the barrier means a new safety hazard

More practical but still probably unnecessary is having the planned “passes” be where the tracks are separated by some distance.

But that requires the trains mostly always being on schedule.

I mean maybe something of merit in that, but Spain has nearly 4000km of hitherto excellent and safe high speed rail and Switzerland around 200 km. Who should be giving lessons to whom? ;) Totally different scale of operations