The level of human negligence here is astounding. The system did exactly what it was supposed to (lock the train down if the track can't be confirmed clear), and then a human controller ordered the crew to override the system, and ordered them to proceed at an unsafe speed towards a similarly disabled train?
dimal [3 hidden]5 mins ago
Usually when you look deeper at failures like this, it’s because there’s a morass of bad incentives from the surrounding human system that enforces this kind of behavior.
Here is a plausible alternative explanation:
They’ve probably seen false warnings over and over and overridden them enough times that they lost sense of the risk. They need to keep trains on schedule, using a buggy system, with a manager looking over their shoulder. They override the warnings over and over, nothing goes wrong, and they forget that it may actually be right. Look at the Challenger explosion, Chernobyl, or any other failure like this, and there’s usually a bureaucratic process that has run amok, and the individual is just following perverse incentives that have been socially normalized over time.
So I’ll wait until I have more information before I proclaim this as human negligence and the system doing exactly what it’s supposed to do. We don’t know how often it was doing the wrong thing and confusing the fuck out of the human.
peri-cl [3 hidden]5 mins ago
> "the individual is just following perverse incentives that have been socially normalized over time"
I recently saw a doc on the 2013 Spanish crash and it was full of absurd system problems. The govt pinned it on the driver as best they could but it's clear that it was entirely preventable.
swiftcoder [3 hidden]5 mins ago
> human negligence and the system doing exactly what it’s supposed to do
Negligence is not limited to the single human who issued the order. it's pretty unlikely that their order could have caused this without a significant amount of other negligence that eroded the safeguards. Nevertheless, the negligence is human, not machine in nature.
toss1 [3 hidden]5 mins ago
Normalization of deviance [0], wherein a clearly unsafe practice becomes considered normal if it does not immediately cause a catastrophe: "a long incubation period [before a final disaster] with early warning signs that were either misinterpreted, ignored or missed completely
Whose negligence, though? "The system" isn't just the LZB equipment - the train dispatcher is just another cog inside the same system, and should be expected to occasionally fail just like every mechanical part.
This isn't a game of Hot Potato where the last person touching it goes to jail for gross negligence. You have to look at it through a Swiss Cheese model: every individual safety layer can and will have holes, but a disaster can only occur when all of those holes align.
Why did the LZB system fail? Why did the train dispatcher use the wrong backup procedure? Why did a backup procedure with zero safety checks even exist? Why did the train operator accept this backup procedure? Why did the train allow high-speed driving under those unsafe conditions?
It does indeed seem like the train dispatcher made a big mistake, but that was far from the only thing that went wrong, and it would be myopic to use him as the scapegoat for a far larger systemic issue.
Zigurd [3 hidden]5 mins ago
Overriding safety systems is itself a safety capability. But this wasn't a failure of the safety systems. It wasn't even a failure of the train drivers who had been over using safety system overrides. It was a management failure for not noticing that over use of overrides.
sznio [3 hidden]5 mins ago
why does the dispatcher even hold the right to override the automatic system by themselves? this should involve multiple people, at least a signoff by a superior.
bobthepanda [3 hidden]5 mins ago
The automatic system will fail at some points so manual dispatch is needed, which is how this all happened
avereveard [3 hidden]5 mins ago
Dispatcher, conductor at that time could not have know that dispatcher ordered manual bypass ignorig the rest of the guardrails of a traffic resume procedure
barbazoo [3 hidden]5 mins ago
Not OP but I'm imagining we'd ask the question why the "dispatcher ordered manual bypass ignoring the rest of the guardrails". They're saying it's all slices of cheese in a system that failed here.
gregoriol [3 hidden]5 mins ago
It seems that one of the train conductors did know that it was not the procedure and tried to warn of the problem.
larodi [3 hidden]5 mins ago
Indeed the system is all of it - all gear on another level of abstraction where it as a whole is just enabling processes, not the thing running it.
kazinator [3 hidden]5 mins ago
If you ignore a road sign and run someone over in your car today, nobody will make systemic excuses for you.
Someone was driving the train who couldn't estimate the stopping distance relative to speed.
If a car is stalled in the middle of the road, and you hit it, that's on you. 200% if a reflective warning triangle was up 100 meters back.
bobthepanda [3 hidden]5 mins ago
Trains take a long time to stop even at moderate commuter train speeds because they are so heavy, let alone high speeds of 300km/h+.
At least one of the failures here is that the dispatcher authorized such a high speed, in other systems I am familiar with, generally the procedure with a signal fault is to crawl at a speed such that the train can stop in line of sight distances.
In fact, that is the Spanish protocol, which for some reason was bypassed by dispatch even after the train driver had questioned it:
> Under normal protocols, the driver would be expected to continue moving at a maximum of 40km/h according to their line of sight, and not at normal speed on a track designed for speeds of up to 200km/h.
stetrain [3 hidden]5 mins ago
If a stretch of road continues to have frequent crashes even though a sign is present, it is worth examining why that sign alone is not solving the issue.
Air travel is as safe as it is because we don't stop the investigation at "pilot error" but instead ask why the pilot made the mistake, and why a single mistake was able to lead to loss of life.
mdemare [3 hidden]5 mins ago
Yeah. This single accident was more deadly than all commercial air traffic in the EU in the past 10 years together, while 50 deaths per day is the average for car crashes in the EU. Wild orders of magnitude difference in safety.
Rough estimate: by car, you can travel from Lisbon to Talinn (4000km) 100,000 times before expecting to die; by train, almost 4 million times, by plane 400 million times.
pixl97 [3 hidden]5 mins ago
I don't mean to pick, but it seems like you have near zero knowledge of how train systems work.
You are 100% dependent on your safety and monitoring systems because almost every problem that could come up is beyond the horizon of your human senses. Stopping distances are in thousands of feet to miles depending on the train size and weight. Add any curves and that's far beyond your visibility.
Then you add in management complaining that you're too slow and you need to do things faster and cheaper or you'll lose your job. Things turn from solution culture to blame culture.
Then you add in false errors and warnings in a system that teach you to ignore them and an upper management that doesn't fix them.
Then you have the day like hundreds of others where warnings are going off, management is yelling, but this time there is a stopped train around the corner and everyone dies.
This is a systemic problem.
SkiFire13 [3 hidden]5 mins ago
> Someone was driving the train who couldn't estimate the stopping distance relative to speed.
The stopping distance for a train this size and this fast is around 2km. Good luck estimating that by sight. There is a reason the normal protocol has a 40km/h max speed for traveling according to line of sight, which the driver was told wasn't needed.
ahelwer [3 hidden]5 mins ago
I wish this were true, but there is basically no consequences for drivers in the situation you described. The most egregious example I can think of near me was in 2022 when a kid was crossing a flashing crosswalk with his bike near Tacoma, and truck had stopped to let him cross. A woman ignored the crosswalk signal and used the adjacent lane to drive past the stopped truck and hit the kid, killing him. The woman was never criminally charged. She didn't even experience any consequences for her driver's license.
Indeed, car crashes tend to just blame one (or more) of the drivers. Nobody excuses a foolish driver with systemic excuses.
On a surely unrelated note, car travel is by a substantial margin the most dangerous mode of transport most of us ever use, and the most dangerous activity most of us routinely engage in.
wjnc [3 hidden]5 mins ago
I would argue that we should look at systems-level explanations. The human factor is so glaring we can get caught up in it. There are what, 50?, high speed trains in movement in Spain at the same time. Even GPS + Starlink + 1 monitor (is that 50k€?) could have prevented this. But it happened, and the question is what is going on with train security in Spain in general for people to (be able to) make such decisions.
jonny_eh [3 hidden]5 mins ago
After learning about a sufficient number of such "accidents" I'm now convinced the cause is never "operator error", it's always a system error. It's the humans that design (or oversee their design and implementation of) those systems that are at fault.
Maken [3 hidden]5 mins ago
The current control system dates from the early 90s. They started rolling a modern system with more redundancies and automatic blocking in 2022 but it's still not fully deployed.
siva7 [3 hidden]5 mins ago
I'm pretty sure we had modern computer systems around 1990.
1718627440 [3 hidden]5 mins ago
PZB is from 1934. Arguably always prioritizing deploying the most modern system on the highest profile lines, is what prevents us from properly rolling out the basic safety systems everywhere.
djankauskas [3 hidden]5 mins ago
PZB is only used up to 160 kph, and relies on wayside signals being read by operators. That's not possible on a high speed line. A more sophisticated signal system is simply necessary here.
swiftcoder [3 hidden]5 mins ago
These high speed trains are pretty recent. Are we really not upgrading safety systems past the 1930's when upgrading a line from ~80kmph to ~300kmph?
1718627440 [3 hidden]5 mins ago
I was only talking about the general problem domain, not about this specific location. The current safety system is also not was has caused this, likely. Or rather it has caused this by it's availability, not by it's safety.
iSnow [3 hidden]5 mins ago
According to the article, the track had LZB, though.
1718627440 [3 hidden]5 mins ago
And according to the article the signalling system reported, that the track is blocked.
1718627440 [3 hidden]5 mins ago
Trains are still not able to assess properly where they are, even using satellites and inside train sensors. Of course there is research on that, but it's still an unsolved problem. (Current alternative is to put markers in the track, but that's also expensive at scale.)
ricardobeat [3 hidden]5 mins ago
Attach a device to the train that will drop / attach beacons at regular intervals. Do it once.
This is just one viable solution out of dozens that anyone can come up with in minutes. The idea that 'we don't know where the trains are' is a thing in this age is absurd and an entirely political problem. You could even monitor it from real time satellite video at this point.
Pragmata [3 hidden]5 mins ago
Yeah and that's fucking ridiculous and a damning indictment of the glaring incompetence of train companies.
If I can have reasonably accurate gps readings of my phone while I'm on the train, there is zero reason for train companies to not have systems that are at least as accurate.
AnimalMuppet [3 hidden]5 mins ago
Part of the problem is multiple tracks. Those tracks may be only 10 feet (3 m) apart. (I don't know if high-speed rail lines in Spain are that close, and I don't know if the line where the accident occurred was double track.)
"Reasonably accurate GPS" trying to determine which track you're on at 150 mph is not as simple as you make it sound. Yeah, it can determine how far along the track you are. But when you get two trains moving toward each other, each at 150 MPH, do you really trust that GPS to tell you that they're on different tracks?
busywaiting [3 hidden]5 mins ago
Trains can't change lanes without warning like a Nissan Altima on the Dan Ryan Expressway. The only way a train can move from one track to an adjacent track -- or get on the first track in the first place -- is if switches are set to allow the train onto that track. And on any modern high-speed line, those switches are centrally controlled by dispatch.
Keeping track of which parallel track a train was on automatically was a solved problem a hundred years ago, using relays and lights and hard-wired logic. Adding computers and GPS greatly increases the precision with which dispatch knows position and speed along the track, but knowing which track has not changed in the last century.
iggldiggl [3 hidden]5 mins ago
Yes, but as long as the central signalling system is working, it already knows where the train is, with no need to involve GPS. (And where modern signalling and train protection systems need increased precision as compared to the granularity of track circuits/axle counter sections, the solution usually involves a combination of on-train odometry plus track balises at occasional intervals in order to reset any inaccuracies that might have accumulated.)
What we're talking about here is some sort of TCAS-equivalent for the case where the central signalling is down – while it's easy to accurately localise trains with the aid of a central signalling system that authoritatively knows about the infrastructure layout, it's quite more difficult when you're trying to do the same thing in a decentralised, train-local fashion.
And as of now, I suppose that RCAS (or RCAS-like systems) is best suited for (especially minor) single track branch lines that don't currently have a full-scale signalling system already up-and-running, but instead still rely on "Timetable & Train Order" and similar systems.
Single track means that at least outside of stations, collisions can be reliably identified without much danger of false positives (and for station areas you can just institute a blanket speed limit to compensate for the gap in RCAS coverage, which might not even be any lower than the speed limit required for traversing diverging/spring-operated/hand-operated points there anyway), and no already existing full-scale signalling system means that RCAS actually provides a significant safety benefit and is therefore likely worthwhile from a cost-benefit-analysis point of view, too, if you're actually regularly operating multiple trains simultaneously on that kind of infrastructure.
Whereas on multi-track mainline railways avoiding false positives is much harder and normally you should already have proper signalling and train protection systems in place anyway, so the additional safety benefits of RCAS would be much more marginal.
pixl97 [3 hidden]5 mins ago
>Trains can't change lanes without warning
Oh, they can, but it's usually a very traumatic event.
1718627440 [3 hidden]5 mins ago
Basically what was the case with the previous accident in Spain.
esafak [3 hidden]5 mins ago
It's very easy since there is limited ability for trains to change tracks, so the location history of the train is a strong indicator of which track it is on. Even Google Maps can tell you which lane you are in since god knows when, and cars can freely change lanes. And that's just consumer software. For something commercial like a train they could trivially solve this problem with something more robust. But I'm not familiar with the Spanish system; how much of the engineering did they do?
brookst [3 hidden]5 mins ago
There are switches that move trains between tracks. Now you need every switch to report, keep a history of that. Many trains also separate and combine. Trains sometimes go backwards to be switched.
It's not impossible. But handwaving GPS placement of trains at the correct location, direction, and track deserves more than a handwave as trivial.
esafak [3 hidden]5 mins ago
All of those failure modes can be accommodated. I fail to see anything here a competent engineer couldn't address. I speculate it's not a technical problem, but an operational and cultural one. This is not rocket science.
1718627440 [3 hidden]5 mins ago
But it must be also cheaper and more reliable than the current system, otherwise nobody is going to implement it.
kube-system [3 hidden]5 mins ago
Google maps gives me the directions for the express lanes when I'm in the normal lanes and vice versa like 50% of the time, and that's an order of magnitude greater error in distance than the distance between adjacent train tracks. And several orders of magnitude greater failure rate than is acceptable for a safety system.
AnimalMuppet [3 hidden]5 mins ago
Yes, it can tell you. How perfectly, though? Perfectly enough to bet 60 lives on?
When Google Maps gets wrong what lane I'm in, nobody dies. It can be right 99% of the time, that's good enough. It's not good enough for a train system, though - at least, I suspect it's not. I'd want a lot more than "it works in my car" before I trusted it.
californical [3 hidden]5 mins ago
Can we just have it as an additional data point, on top of what we should already know from where the train should be from switching history? If we get 99% accuracy, is that enough to check with an operator “specify which track you are in, left or right” when the measured value is different than the expected?
giovannibajo1 [3 hidden]5 mins ago
Would that work in tunnels and forests too?
IAmBroom [3 hidden]5 mins ago
Tunnels are controlled by a single block - only one train can ever be allowed access at once, period. Until the "current" occupant train is verifiably out of the tunnel, that block is forbidden to all.
Forests are irrelevant; rail right-of-way contains no trees, and is wide enough to assure clear "view" of satellites.
1718627440 [3 hidden]5 mins ago
You are just answering how the current system actually works. This discussion was about how a hypothetical system works based on GPS or radar alone.
1718627440 [3 hidden]5 mins ago
> a damning indictment of the glaring incompetence of train companies.
No, what I describe has nothing to do with the companies, that's the research state. It's just an indictment of you making bold statement about a subject, you don't now enough about.
> I can have reasonably accurate gps readings of my phone
Would you dare to cross on a rope over a deep valley, blind using only GPS readings of your phone? Because that's kind what you are suggesting, expect you also move a few hundred other people.
swiftcoder [3 hidden]5 mins ago
> Would you dare to cross on a rope over a deep valley, blind using only GPS readings of your phone?
Hang on, this is nothing at all like that - trains run on fixed tracks. The only bit of data we are interested in for collision avoidance is the linear offset along the track. Even the shittiest GPS fix of all-time would give a good-enough intersection with a fixed path to avoid crashing into a second stationary train in the open country-side (do you see any satellite line-of-sight blockers in the crash footage?)
1718627440 [3 hidden]5 mins ago
> The only bit of data we are interested in for collision avoidance is the linear offset along the track.
So that is naive, but assuming that would be all that you need, with GPS you would also need the positions of all other trains. But why would you transmit all this information to every train, instead of just computing the collisions in a central node? (That's what is done now.) A better fit for what you suggest would be radar, and this does exist. [1] But that's where your original assumption is naive. You regularly pass other trains within <2m at high speeds, so linear offset is not all you need.
> But why would you transmit all this information to every train, instead of just computing the collisions in a central node?
Because central nodes can fail (as they did here, both human and machine), and providing this redundant data allows both the computer and the human-in-the-loop on the fast-moving chunk of steel to independently validate the decisions coming from the central node.
> You regularly pass other trains within <2m at high speeds, so linear offset is not all you need.
In this collision, both trains were on the same track. So while we obviously care about adjacency issues in the general case, this specific failure mode can be detected purely via a linear offset.
1718627440 [3 hidden]5 mins ago
You can and do have redundancy in the central node already. Also that's not what failed here.
> In this collision, both trains were on the same track.
Yeah, but how do you distinguish that? So when I understand you correctly, what you want is: Find another moving chunk of metal in the radius of 2km, which moves toward you, but not in a direct or ballistic trajectory, but in a arbitrary complicated trajectory, but which can lookup in a database. Also you are operating in the real world, so there are potentially houses, trees and mountains in between. I guess that would be possible, but it would be really expensive. Your best bet would be to adapt a missile detection and targeting system from the military. A system which does exist and is somewhat similar is RCAS (https://www.dlr.de/en/kn/research-transfer/projects/next-gen...).
swiftcoder [3 hidden]5 mins ago
> Yeah, but how do you distinguish that?
By enumerating the tracks?
I feel like you are intentionally trying to turn this into a spherical cow situation by insisting on solutions that work in an information vacuum. All of this sort of problem in the real world is solved by sensor fusion from multiple data sources.
Trains are captive to a particular track - they can only change tracks at specific pre-determined junctions. With a pretty minimal sensor feed from each junction we can statically determine which track segment a given train is on. With GPS we can shrink that segment length down to a few kilometres. By sharing data persistently every single train can validate that central command-and-control is not about to run it into another train from behind...
There cases which are genuinely challenging engineering problems (i.e. derailments that impinge on adjacent tracks), but this trivial case of bumper cars is not one of them.
1718627440 [3 hidden]5 mins ago
>> Yeah, but how do you distinguish that?
> By enumerating the tracks?
How do you distinguish that the <2km away detected moving train runs on your track on not on the one directly besides you?
> Trains are captive to a particular track - they can only change tracks at specific pre-determined junctions.
Yeah, but you do not know which one it runs on. Your entire point is that you do not trust the information the infrastructure knows. If you do allow to use information from the infrastructure, then why not use the sensors that already exist along the whole train network? It's also very unlikely that there is something electrically connecting the two rails of a track, that you would like to run over. So why wouldn't you trust that information, but some vague GPS signal?
> we can statically determine
But the current state of the art is, that you deterministically and provable know where a train is. Why would you use a more expensive, less safe system? The current focus to reduce errors in computing train conflicts is to prevent random bit flips due to radiation at the same time in three different computers running different software.
> I feel like you are intentionally trying to turn this into a spherical cow situation
The situation where you proposal makes sense, but the current system does not, is a spherical cow situation, that's my point.
swiftcoder [3 hidden]5 mins ago
> that you deterministically and provable know where a train is
You are the one who framed this conversation as it not being solved how to deterministically know where a train is. Everyone else in here has been kindly suggest that if perfect information is unobtainable, then we should work with what we have
1718627440 [3 hidden]5 mins ago
Oh, I see how you could think that, without context. That's in fact not what I wanted to say. I meant that pretty literally. The infrastructure of course knows where the train is.
> Trains are still not able to assess properly where they are, even using satellites and inside train sensors. Of course there is research on that, but it's still an unsolved problem.
*Trains* on there own! This IS a hard problem, how to do that with any other infrastructure. It IS current research and not yet solved. That is for example relevant, if you want to be able to run trains at full speed <1m tolerance, so that you can have more than one train stopping at a station <60s. All while still not paying for infrastructure and maintaining backward compatibility with a century old trains. (I mean in the future you could use the same to also couple trains at full speed, but that's still sci-fi.)
thaumasiotes [3 hidden]5 mins ago
> That is for example relevant, if you want to be able to run trains at full speed <1m tolerance, so that you can have more than one train stopping at a station <60s.
...is that something you'd ever want? In general, it is, but the way it's handled is by having those trains stop on separate tracks.
Running multiple trains through the same station track in under 60 seconds means that all passengers must embark and disembark in under 30 seconds. That's very tight. I would venture to say it's too tight and meeting this goal would make the trains worse.
(And if passengers aren't getting on or off the train, then the train isn't stopping at a station.)
1718627440 [3 hidden]5 mins ago
In a society where building more rail is not welcomed, trying to get more out of the existing tracks becomes critical. In a metro, time for embark and disembark of 30s is not unreasonable. https://de.wikipedia.org/wiki/Fahrgastwechselzeit#cite_ref-d...
tancop [3 hidden]5 mins ago
Redundancy in a central node is an oxymoron. Safety critical systems need to work 100% of the time if any single node fails, and stop safely if there are multiple failures and it can't work properly. Doesn't matter if each individual node is 100% reliable by itself because connections fail too.
1718627440 [3 hidden]5 mins ago
You can still have redundancy in the computation, that isn't prevented by being in the same location.
> Safety critical systems need to work 100% of the time
Railway safety must be safe 100% of the time, but not available 100% of the time. Also the point of a signal box is to make decisions about the order of train assignment to track. You absolutely do not want multiple points of truths for that.
collabs [3 hidden]5 mins ago
The way I think of it, divide the tracks into segments. Before you put a train on a segment, you must ask a question - is there a train on it. There are only two answers possible, No, and something else. If it is something else, stop. Don't let the train on that segment.
There are optimizations possible like make segments smaller etc but the original algorithm is trivial. If we can't figure things out, we make segments longer and we slow down the trains until we can. I am positive for a sufficiently large track segment and a sufficiently slow train, we can always answer the question with a no.
1718627440 [3 hidden]5 mins ago
Congratulation you are reinventing 1890 state of the art.
jdmichal [3 hidden]5 mins ago
You've "invented" interlocking railway semaphores, after which the computer science concept was named.
i don't see where it says they should use gps alone. In fact it even mentions starlink in addition to gps.
>Even GPS + Starlink + 1 monitor (is that 50k€?) could have prevented this.
My reading on that sentence was that even a simple setup would have been sufficient to prevent this. Not that it should be the only thing.
1718627440 [3 hidden]5 mins ago
My reading indicates, that "Even X could have prevented this." means that X is able to solve the issue on it's own. Otherwise X would in fact not prevent it.
- I don't think X would actually work, without actually eventually recreating part of the current railway control system, and the current rail control system alone already works better.
- I don't think another less reliable more costly safety system helps, when the current one already stated that there is a problem, and it was ignored.
swiftcoder [3 hidden]5 mins ago
> Trains are still not able to assess properly where they are, even using satellites and inside train sensors. Of course there is research on that, but it's still an unsolved problem
Throwing up our hands about how hard a problem this is seems like a ridiculous position to stake. If we can design self-driving cars, that operate safely in far less controlled environments, we can figure out the linear offset of a large vehicle traveling along a physical rail running along a fixed pre-determined path.
iggldiggl [3 hidden]5 mins ago
> If we can design self-driving cars, that operate safely in far less controlled environments
Self-driving cars aren't supposed to drive quicker than they can look ahead, which makes the problem way easier because you don't have to figure out how to detect obstacles ahead of time and can simply rely on vehicle-local information to stop if necessary. And because cars can brake way more rapidly than trains, it means you can still drive reasonably quickly even within that limitation.
Plus in an emergency, cars have steering as an additional degree of freedom to attempt getting out of any nasty situation that may have developed.
(And of course the socially expected safety standards for cars are quite a bit lower than for public transport…)
Trains on the other hand have braking distances on the order of a kilometre or so, and high-speed trains at full speed several kilometres, so trying to get by on local data only is hopeless and the usual strategy is instead having central signalling system that can accurately track trains and coordinate their movements.
1718627440 [3 hidden]5 mins ago
I said nothing about "throwing up out hands", this is a current research topic. But you can hardly blame the workers for not using a system, the researchers haven't invented yet.
> If we can design self-driving cars
We can not design self-driving cars to the safety standard that is required for railways. They are way less safe than the current half-manual system for railways. What you suggest is using less automatic safety systems than what we currently do.
knottn [3 hidden]5 mins ago
Has there ever been a case where two self driving cars collide with each other? I hate to be part of the peanut gallery, but as a totally naive person when it comes to railway safety research it really does seem amazing train collisions can’t be easily prevented with gps, lasers, sonar or various other trivial ways. Even the crash in question seems like it might have been easily prevented by having a second human in the loop. Maybe I and others just suspect the difficulty isn’t so much technological as it is financial.
Fargren [3 hidden]5 mins ago
> Has there ever been a case where two self driving cars collide with each other?
I don't think that's relevant to trains. Cars can avoid a collision much more easily than trains can. Cars can swerve, and if they are at a distance at which line of sight tells them they will hit an obstacle, they are moving slow enough to stop before hitting that obstacle. Trains have to stay on tracks, and they need up to 4 kilometers to stop moving.
The constraints are very different, so the solutions and tradeoffs will be different too.
1718627440 [3 hidden]5 mins ago
As far as I am aware, there has been no non-supervised train in a general train network. (They exist in closed systems.) However whether the train is self-driving is really not the issue here. In current railway safety systems (even from the 80s) a crash is about the same probability as random bitflips. However reality is too messy, so that the availability is not satisfactory enough to not use a human fallback, and then you are back to the assisted human error rate.
Current operation of a train is basically self-driving and supervising driver. So if you suggest "just use self-driving", you make the system less safe, not more, because it means just getting rid of the human supervisor. This is not currently done, because it would be too insecure. It might be done in the future, but rather because less safety is going to be accepted in favor for getting rid of the costly human.
A self-driving train will happily cause a crash, if the target is "drive with high-speed in that segment currently occupied by another train". The issue is that that becomes a target, not that there is a human in the loop.
IAmBroom [3 hidden]5 mins ago
> A self-driving train will happily cause a crash, if the target is "drive with high-speed in that segment currently occupied by another train".
Sure, if you allow trains to ignore safety completely, then accidents will occur. That is a ridiculous statement.
1718627440 [3 hidden]5 mins ago
Yes, if the dispatcher issues faulty movement authorities, it's futile to look for the error in the train. That was my point.
wewtyflakes [3 hidden]5 mins ago
Why is it that these fatal train accidents have happened multiple times in Spain, but never in Japan, even though Japan has been doing it high speed rail longer, and at 10x the passenger volume than Spain? Do they have some alien safety technology unavailable to Spain?
1718627440 [3 hidden]5 mins ago
The were several other train accidents, where it was found out, that the drivers have made races, who can stay above the speed limit longer. But I think that was already in the 90s. There is/was definitely something at fault with the safety culture.
But there was a recent incident in Germany as well (https://en.wikipedia.org/wiki/Burgrain_train_derailment), which is somewhat similar to the earlier accident in Spain this year. Targeting high value projects, while not paying for proper maintenance is not something that only happens in a single country.
wewtyflakes [3 hidden]5 mins ago
Yes, you can say that high-speed rail crashes are not limited to one country (though Spain has had multiple this year alone), but you can't say that it has ever happened in Japan. So for you to argue up and down this thread that everyone calling out issues with Spanish high speed rail safety is wrong, as if it is some sort of intractable problem, is bananas.
1718627440 [3 hidden]5 mins ago
I have not stated anything that is specific to Spain in this thread? I do think there is something wrong with the safety culture in Spain, I mean obviously, there was an accident.
> but you can't say that it has ever happened in Japan.
indeed. Japan is a compliance and shame based society. that alone is the foundation of a very strong safety culture, something that southern europe is famous for lacking.
1718627440 [3 hidden]5 mins ago
> that alone is the foundation of a very strong safety culture
> We can not design self-driving cars to the safety standard that is required for railways.
That is completely false. PTC does that, and we've had it for several decades. There are several self-driving cars operating in the world right now. I have never heard of a PTC system causing accidents; those occur in places where the system isn't required (like entering Grand Central).
You keep pretending that avoiding train collisions is too magical to achieve with current tech, but train traffic is easy to limit (but slightly harder to optimize), and systems exist to do that, because rail is unique amongst all forms of travel: if you drop speed to zero for any trains at risk of collision, they are safe. Planes will plummet; most cars are human-operated and you can get rear-ended, etc.
1718627440 [3 hidden]5 mins ago
> That is completely false. PTC does that, and we've had it for several decades.
And they somehow work with radar, lidar and GPS from inside the train? No they work with classical block based systems and on signalboxes. So all the safety systems are outside of a train.
> You keep pretending that avoiding train collisions is too magical to achieve with current tech
Huh?? Railway interlocking exists for more than a century. It's very safe and I didn't wrote anything contradicting that.
djankauskas [3 hidden]5 mins ago
Yes they are, those balises on tracks are the standard technique for both metro and mainline signaling systems at this point. Those balises, often combined with radio communication, are how fully autonomous trains have been operating for decades. (It's possible to use things other than balises, like track radio loops as in LZB or more recently beacons or LIDAR, but balises are standard and pretty affordable).
1718627440 [3 hidden]5 mins ago
Yeah, that works and has been for a while. I was talking about non-track based safety systems. You can have balises in specific locations, but you can't have them every few centimeters on your whole network.
djankauskas [3 hidden]5 mins ago
I guess I'm confused by why non track -based solutions are necessary? ETCS L2 would gracefully handle a system restart and automatically force a 40kph speed limit until a train traversed the unknown track proving no occupancy, and allowing proceeding trains to go faster. This all works on a track-based system.
1718627440 [3 hidden]5 mins ago
Because railway infrastucture companies would like to not pay for them, not build more tracks and still get more capacity due to "digitization".
djankauskas [3 hidden]5 mins ago
Not sure what you're arguing, the line affected by this tragedy was migrating to ETCS L2. Its installation costs are getting lower too, I don't think there's an actual problem here.
1718627440 [3 hidden]5 mins ago
I wasn't talking about a specific line at all. Research doesn't need a clear problem to try to find better solutions. Also Deutsche Bahn does think there is enough of a "problem", because they do support that research.
wjnc [3 hidden]5 mins ago
Would you mind sharing some more of the why it is still an open problem? (I know I know little about this subject.) I understand satellite positioning isn't definitive and did not suggest it should be the /primary/ risk mitigating factor. But even as a tertiary or lower risk mitigating factor, this would have been a worthwhile investment. (Sorry for the bleak introduction of economics.)
And some problems are just _open_ to outside looks. My assistant tells me that the room for error in trains on one dimension ('left - right') is mere 10s of centimeters. I understand that problem. But what track you are on, isn't that obvious to the human in the cabin? (Again, simplifying, not flaming. Production ready safety is _hard_.) So could a vision based solution help count tracks from left to right? (Assistant: "US PTC, on about 54,000 route-miles, uses GPS for the lead locomotive plus crew-entered track information and switch position".) So you use the dimension that matters most in crashes (forwards / backwards) from satellite, augmented with vision or human based left-right positioning. Some trains already have sensors to sense things like leaves on the track to adjust speeding and braking... So the sensor based approach is already there.
Perhaps I am read as suggesting that the problem is easy, and that is not my intention. But for cars this was solved decades ago for routing and years ago for self-driving. I use that daily. Flying is organised with a very clear 6 sigma approach. Crashes are nearly always situations where events / risks stack. Trains (in Spain)...?
Tl;dr - Safety is a function of (human; process; technology) and there is clearly something lacking for trains, when compared to other types of transport.
1718627440 [3 hidden]5 mins ago
So that's a lot of questions, that I all can't answer in full.
> Would you mind sharing some more of the why it is still an open problem?
Because for train sensors, there is a small drift which accumulates too much, hence it is synchronized by magnetic position markers in the tracks.
> I understand satellite positioning isn't definitive
Yes, and the point is it might be some solution if we would have the safety systems from 1860. But we do not and hence it needs to be more accurate than the current system, and it is not and in addition also more expensive (and subject to remote influence and reliance on potentially adversary nation states).
> Sorry for the bleak introduction of economics
No, economics is basically the primary constraint for safety. We could pay million people to make sure a single person does not stumble if we want total safety, but that's completely pointless, and also these million people would starve, because no one is producing food anymore.
> But even as a tertiary or lower risk mitigating factor
But for that it's too expensive and still unreliable. There is RCAS[1], which I already linked elsewhere in the thread. That's basically cutting edge and too expensive to introduce everywhere. Also previous safety systems are already not rolled out enough, which is causing these accidents, so rolling out yet another expensive system is not going to improve much.
> But what track you are on, isn't that obvious to the human in the cabin?
Yes, but if it is already known, why use GPS to calculate the same information with more error?
> So could a vision based solution help count tracks from left to right?
If the train driver or dispatcher makes use of vision to assess the train position, the error will be higher than the current sensor/electric-resistance based system.
According to Wikipedia, ASFA being introduced in 1975 is rolled out in the entire Spain network. ETCS which is the European standardization seems to be rolled out on all high-speed lines or currently being rolled out.
> So you use the dimension that matters most in crashes (forwards / backwards) from satellite, augmented with vision or human based left-right positioning.
Duh, that just sounds like trains would be operating blindly in space currently and need to assess their approximate position.
> Perhaps I am read as suggesting that the problem is easy, and that is not my intention.
No, the issue is that you are suggesting far more complicated solutions to already solved problems, with simpler systems in operation for decades. The current system is that nobody in the train even has a say on where the train goes, so the problem you are trying to prevent doesn't even exist. This IS why it's way more safer than a car. There are movement authorities, that define from where you are allowed (and have to) drive with your train. The problem is not, that the train driver isn't able to know where he is and hence drives wrong or too far (that would be prevented by the on-board safety system), but that the movement authority itself is faulty.
On an up-to-date signaling box (withing the past 6 decades), even the train dispatcher is no say in safety questions. You could put a monkey in charge of it. There would be chaos, but they would not cause a crash. The current job of a dispatcher in normal operation is to assign resources to prevent deadlocks and to implement vaguely defined priorities. (Basically the equivalent of the public thinking a programmer is a code monkey, while the actual point is clarifying stakeholder interests.)
The actual issue here is, that while these safety system have a very small false positive rate, they do have a too large false negative rate for there to be an acceptable availability. Hence in the latter case, the human needs to take over and then you are back to a much higher false positive rate. The issue would be alleviated by relaxing the constraints on cost per availability. Either by allowing for less availability or by reintroducing more humans, so that the system situation can be assessed by humans directly.
These accidents are caused as follows: the automatic system fails, because the internal state of the system does not match the actual state of the world. Hence the human needs to take over. But the human also needs to rely on some system to know the world state. Which systems can he trust, given that the whole situation is that the systems report that he can't trust them? So he needs to make some decision and in most cases, that decision is still correct. But there is still an error rate to that, and then something like what we are discussing happens.
> But for cars this was solved decades ago for routing and years ago for self-driving.
This is absolutely not solved for the cars, and to the sense that it is, it was solved and rolled out from the 1870s onward for railways using mechanical computing systems, the switch to using electricity happened in the 1910s.
> Flying is organised with a very clear 6 sigma approach.
You are correct, that aircraft safety systems need to be designed to a higher reliability than railways, because on a rail you can always stop in case of an error, while in the air such a choice doesn't lead to a safe state. But if you compare these safety systems, basically aircraft is operated like railways used to be operated in the 1920s. (My peers actually had a task to compare them and find ideas from one that can be applied to the other. While there is a lot of automation to be taken from rail that can be applied to the aerial industry, there is not really much that can be applied the other way.) It is also operated with the amount of personal than 1920s railways. That's because there is a lot of money in aircraft, while railways are mass-transit and need to be cheap. If you would operate today's railway with the amount of human oversight than in the past, it would be a lot safer than aircraft.
> there is clearly something lacking for trains, when compared to other types of transport.
What are you talking about? Railways are so much safer than cars. https://news.ycombinator.com/item?id=50288518 Yes, there are less accidents in planes than in trains, but this is due to what I already explained.
GPS-based PTC absolutely does what you describe. It has long been solved.
1718627440 [3 hidden]5 mins ago
No, it does not do, what I described. I was talking about solely determining it inside the train. At least Wikipedia indicates it is similar to LZB or ETCS. I am not familiar with PTC itself.
That's a research topic, because the infrastructure companies would like to not pay as much for maintenance and still have a high sequence of trains. Also with track based train control systems you can only have very high resolution in specific places, where you place your track-side infrastructure, but it would be nice to have that resolution anywhere you like.
cryptoegorophy [3 hidden]5 mins ago
oh man, the override thing is super dangerous. I use FSD in Tesla a lot and there is a lot of times I "override" with the gas pedal because I think it phantom breaks or being slow and there were at least 2 cases where there was legitimate reason to stop (person crossing in my blind spot).
thatfrenchguy [3 hidden]5 mins ago
They have a failsafe to use (visual) block backup signaling on that line and used it incorrectly. 200km/h is right at the border where you don’t need in cabin signaling.
tencentshill [3 hidden]5 mins ago
Too bad they don't run it with AI. Then it would be nobodies fault!
1718627440 [3 hidden]5 mins ago
Sorry, but ordering trains to drive manually after the system locks itself down, is the proper procedure. Of course you are still supposed to only send trains to free sections, but the error is in that step, not that they ordered a train to drive on it's own.
Also the fallback procedure is also aided by automatic systems and a sizable number of accidents in the past were caused by that information being faulty.
julik [3 hidden]5 mins ago
It is the proper procedure, and it does come (in a lot of countries, AFAIK) with a lot of guardrails:
There will be a so-called "train order" allowing passage of a specific section ignoring the safety system warnings, which has strict validity limits both in time and in the area where it applies, usually denoted by specific hectometric mileposts
When cab signaling is involved (LZB is one of these) and it malfunctions, the entire system normally changes to "driving on sight only" - which indeed limits the train to 40, 30, 20, sometimes - 15 km/h (see https://fr.wikipedia.org/wiki/Marche_%C3%A0_vue) or the line gets switched to lineside signaling - if it is available.
I don't know how you could violate all of those rules - both from the driver's side and from the traffic control side - but it sounds absolutely horrible. Like an override of at least 2 (if not 3) very explicit safety margins.
dist-epoch [3 hidden]5 mins ago
There are audio recording from this incident where you can hear the "train orders" being given and acknowledged.
They were the wrong orders apparently.
AdrianCX [3 hidden]5 mins ago
Why is that?
I remember a long time ago I was stuck in a train in a field a considerable time because of a similar failure and conductor just wouldn't move unless green
I was expecting the same here, conductor is the first to die so just refuse until the idiots fix their system
1718627440 [3 hidden]5 mins ago
> Why is that?
What exactly?
A conductor always just gets a movement order. They are not able to assess whether the track is clear, that's the reason why the signalling system exists in the first place. How they get that movement order doesn't necessarily tell what the security steps were to back it.
Of course an attentive conductor can notice and mention there something being weird ("Doesn't the other train normally arrive first?"), but that's a rare lucky occasion, nothing to be relied on. And they just need to swallow the answer ("No, you go first today...") anyway.
> and conductor just wouldn't move unless green
The conductor won't ever move unless they get a movement authority, which most of the time is a green signal.
AdrianCX [3 hidden]5 mins ago
so in this case, couldnt conductor just say - make it green, not my problem, staying still until then
1718627440 [3 hidden]5 mins ago
Why would they trust "a random blinking green light", but not a written and stamped order? Yes, they could do that (and sometimes it will actually prevent an accident), but it will be more being a snowflake, then being a decision for safety. A conductor is simply not responsible for whether it's safe to drive on a given track. Their equivalent is not a car driver.
AdrianCX [3 hidden]5 mins ago
The "random blinking green light" is generally more reliable
Being a snowflake here has 2 benefits:
1. Getting company managing tracks to fix the lights (they need to deal with angry customers and pay off damages for delays and more), so there's a direct path from unreliable lights to economic damage.
2. Avoid crashing and killing yourself and passengers on the offchance the person on the radio is a moron
1718627440 [3 hidden]5 mins ago
> The "random blinking green light" is generally more reliable
Yes, but not because of the light itself, but due to the safety steps done before. Which should also have happened before the movement order in any other form.
As a train driver, you do not have the information required to distinguish these situations. If drivers simple refuse all movement orders, besides "green lights", running trains will become a rare occasion and the drivers will simply get fired for not doing their job. _The train driver is not the one who decides where a train goes._ For this safety-relevant decision a driver is (roughly speaking) nothing more than an innocent bystander.
You can think of a train driver more of the person who makes sure the automatic engine works correctly and also has an eye, that nothing weird happens. Most of your train driver education is knowing how the train works and how to get a broken train back working fast. In addition you also learn the safety protocols how you get the information in which state the engine should operate in. This is what train signals are, it's not really the equivalent of a green traffic light for car traffic.
robhlt [3 hidden]5 mins ago
Many train systems have a trip-stop on signals that will automatically activate the trains's emergency brake if one passes a red signal.
It cannot be bypassed, if an operator must go through a red they have to manually reset the e-brake on each car once it passes the signal.
So that's why my train slowed to 40kmph when the Norwegian Telecom died for a few hours 3 weeks ago.
_trampeltier [3 hidden]5 mins ago
Yes, 40km/h is for driving on sight in most Europa. I think in France it's even 30km/h.
masfuerte [3 hidden]5 mins ago
In the UK at night it's walking pace. Literally. The guard gets out and walks and the train follows. (At least that was the case 25 years ago when I had a very slow train journey.)
inglor_cz [3 hidden]5 mins ago
This really reminds you of the Chernobyl station computer printing all the warnings and recommendations to shut the reactor down when they started playing around with it ... and Comrade Dyatlov overriding it.
Dyatlovs seem to be born everywhere.
juliushuijnk [3 hidden]5 mins ago
It should not be possible for one person to make a mistake of this magnitude.
In case of a disconnected/off main safety system, the train should be limited on a hardware level to not be able to go over 40km/h.
Zigurd [3 hidden]5 mins ago
If I read the description correctly, those hardware level systems were manually overridden, which should only be done in extremis. My guess is that this is going to turn into a normalization of deviance case, since such a cavalier attitude toward safety was unlikely to be one person's first time doing something so dangerous. There was no dilemma here and no time pressure.
Your suggestion about limiting speed after a shut down is a good one. On top of that, the rail operators should have spotted a trend of repeated safety system overrides and investigated why that was happening.
aquafox [3 hidden]5 mins ago
Exactly this was my first thought! I always thought highspeed trains operate under a model of clear sectors where one train is just allowed to enter when it was cleared by the previous train. From my layman point of view, those incidents point to a fundamental design flaw.
notenchange [3 hidden]5 mins ago
Reading the text it seems to me this is due to a very widespread issue in Spain and other southern European countries: people don’t care about the warnings because there are too many false positives.
That’s why people here, when they hear the fire alarm they just wait for it to go off: the probability that it is actually a fire is minuscule… but the alarm triggers a lot.
Not sure how to actually solve this… but I’m also not making excuses for what happened. High speed trains is not the same as a fire alarm in some office building, the people in charge should be held responsible somehow.
PaulDavisThe1st [3 hidden]5 mins ago
I'm a volunteer firefighter in rural NM. We have a commercial property close to us that repeatedly has false alarms on its fire alarm/smoke detection system, to the point where even the best of us are suffering from "the boy who cried wolf" feelings.
Because of this, I discovered that (apparently) NY Fire Department charges $5000 per false call on an alarm system directly connected to the dispatch system.
Somethng to think about.
jcrawfordor [3 hidden]5 mins ago
ABQ Fire charges $300/call for false alarms after the first three. It steps up to $500 after number ten. There is, of course, also the $25 annual permit fee for a reporting alarm system. Failure to comply with these fees is a misdemeanor. Just in case some local precedent will help advocate :)
Honestly it's remarkable to me to think that anyone ever gets to that $500 "excessive" tier, I've had one false alarm where the fire department attended in years of having an alarm system and I was mortified. felt like the biggest idiot in the world.
brudgers [3 hidden]5 mins ago
$500 is probably cheaper than a Simplex service call.
jonah [3 hidden]5 mins ago
Pretty common in lots of places - you get charged after n false-alarms and are required to fix your broken sensors or whatever is causing the issue.
Maxion [3 hidden]5 mins ago
Sometimes code gets in the way. E.g. in the school I went to growing up they had to have firealarms in all kind of closets and storage rooms. We got at least once per semester a firealarm when some teacher went in to sort stuff due to the dust.
js2 [3 hidden]5 mins ago
There's generally two types of smoke alarms each with pros/cons: photoelectrical which are very susceptible to dust and ionizing which generally are not:
I wouldn't think code dictated the alarm type. (I just replaced all nine sensors in my home due to age and went with all photoelectric this time and it was less than six months before I had my first false alarm. Never had any false alarms with previous ionizing type.)
femto113 [3 hidden]5 mins ago
"False" isn't really binary. In my condo building we used to have in-unit smoke detectors wired directly into the building alarm, which meant whenever anyone in any of 200 units burned their toast sirens were blaring. The smoke was real, it just wasn't a threat to the whole building. This would happen once a month or so, and because it's a highrise that sent the big ladder truck down our little street. The fire department got sick of this so we updated a few years ago to have heat detectors that are wired into the building-wide alarm but the smoke detectors only go off locally. False alarms have fallen to basically zero, but the downside is that for reasons not entirely clear to me the new system has to get inspected every 6 months, which includes making sure every one of 200 heat sensors is working, so we get days with 100s of very short bursts of the alarms twice a year.
Animats [3 hidden]5 mins ago
In my aerospace days, our buildings had both ionization and temperature detectors, plus water flow on the sprinklers. Any detection would sound loud buzzers locally, but two sensors, or water flow, had to trigger before everything powered off.
That's common in big installations.
We once got an alarm because the heating element in a computer room air conditioner had turned on for the first time ever. It was defective and started to smoke. Smoke detection tripped, buzzers sounded, lights on a panel showed where the problem was, and alarms went off in the security control center. But this didn't trigger building evacuation or full power down. That took confirmation from a second sensor.
Someone ran into that computer room, saw smoke coming from the A/C unit, and pulled the big red power switch, installed by the safety people, on the air conditioner. Then we had time to shut down normally, the safety people came to clear the alarm, and the HVAC people came to fix the problem.
I kept the burnt heating element on my desk for a few days for people to see.
This is typical for big industrial plants. Bad stuff will happen, and you have procedures for it.
childofhedgehog [3 hidden]5 mins ago
I learned this from my last landlord after I kept causing issues for the whole building by cooking bacon. The detector was installed ABOVE THE STOVE. It was cheaper for him to move the detector than to pay for the repeat call outs over a mildly smoky apartment due to my need for crispy almost burnt bacon…
JumpCrisscross [3 hidden]5 mins ago
Consider investing in powerful window fans. If it's setting off a detector it's causing havoc in your lungs.
infecto [3 hidden]5 mins ago
These are elegant solutions imo.
futureproofd [3 hidden]5 mins ago
For example, my condo in Toronto charges $800 per false call.
munk-a [3 hidden]5 mins ago
I'm surprised the strata was able to offload that to you. Most building corps are in charge of maintaining the fire alarm system especially if it's a tower (rather than just a SFH community under a strata) where unit to unit spread needs to be addressed promptly.
Kinrany [3 hidden]5 mins ago
It should probably be X$ per alarm regardless of it being false or not, minus first N per year.
rtkwe [3 hidden]5 mins ago
Why? The goal is to incentivize property owners to fix broken systems not to pay for the actual cost of responding to a real call. That's covered by taxes.
ralegh [3 hidden]5 mins ago
Depending on who is paying and how much, someone might light a small fire to avoid the fine.
mindslight [3 hidden]5 mins ago
Arson when the fire department is already on the way. Great idea! Firefighters hate this one simple trick.
bell-cot [3 hidden]5 mins ago
I'd interpret the "minus first N per year" to mean that you get a few "free" fires per year - but after that your habits filling your closets with oily rags, overloading electrical extension cords, and smoking in bed will start to cost you.
munk-a [3 hidden]5 mins ago
Fire is one of those things that really sucks for you - but also really sucks for your neighbors.
You never want to supply any reason for someone to demur about reporting a fire.
eastbound [3 hidden]5 mins ago
I'm sure someone somewhere will interpret it a 3 free demos of firefighters at home for their kid, with sirens and light, pretty entertaining (It's a reference to the Freakonomics study that, if you make parents pay by the minutes for being late getting their kid, they basically take the fine as a slightly expensive childcare facility).
uniq7 [3 hidden]5 mins ago
That will also decrease the number of true positives
See also a million USCSB industrial disaster postmortems
prmph [3 hidden]5 mins ago
I've had the thought that:
"known to the state of California to cause cancer"
Should probably be:
"known to the state of California to be a class N carcinogen"
eastbound [3 hidden]5 mins ago
I've deactivated my (EU equivalent of) Amber alerts the second they sent ONE irrelevant notification. It took me a few tries but fortunately they also tried their system a few times A WEEK during installation.
I prefer to risk my life every day at not knowing what the government thinks is really important for me to know.
1718627440 [3 hidden]5 mins ago
It just means that a false positive rate is as dangerous as a false negative rate. Just issuing a warning doesn't come for free when you are designing a security system.
karmakurtisaani [3 hidden]5 mins ago
This is very well illustrated in the fable Boy who cried false positive.
jryle70 [3 hidden]5 mins ago
False positive? How did you know?
mercer [3 hidden]5 mins ago
that sounds like a character from Harry Potter and the Methods of Rationality.
thaumasiotes [3 hidden]5 mins ago
Any lessons in HPMOR are also going to be found in traditional works.
I was interested to find a discussion of the trolley problem in a book of out-of-copyright Norwegian-region folk tales (in English translation) that Amazon recommended.
coopykins [3 hidden]5 mins ago
Something similar is happening in my region after the flood that happened two years ago: The alarm was raised late; Now, even mild rain is triggering an alert.
Guess whats the consequence of that? Less and less people pay attention to the alerts.
ricardobayes [3 hidden]5 mins ago
What you mention makes me frustrated, as it also signals the infrastructure is so underdeveloped even moderate rain grinds daily life to a halt: kids don't go to school if rain is forecast. We need to elevate our professionalism in Spain and not accept African-level infrastructure in the 21st century. It's really sad within one continent we have countries producing AI and photon computing, and others can't even figure out how to put gutters and rain drains.
cbovis [3 hidden]5 mins ago
This is not what it is. The infrastructure isn't THAT bad.
Government officials are terrified of taking the blame for another Valencia style flooding catastrophe so any hint of rain blasts the mobile phone emergency system. Once the alert has been sent the officials can feel safe in the knowledge that they've done something.
jonny_eh [3 hidden]5 mins ago
To your point, a contributing factor here was the front train couldn't start due to either a minor or bogus "security" alarm. Whatever alarm that was, it wasn't worth triggering such a tragic accident.
jameshart [3 hidden]5 mins ago
To be fair the Spanish word for security is the same as the Spanish word for safety: seguridad. It could as easily be a ‘safety’ alarm and a mistranslation.
jonny_eh [3 hidden]5 mins ago
I'd bet this "safety" alarm was minor or bogus, not worth risking lives over.
throwitaway222 [3 hidden]5 mins ago
The fix is to do things right every time, and if we're losing money to false alarms, spend more money to make sure the false alarms stop happening. Make it a new persons problem rather than just making someone "used to it" and start ignoring it.
gambiting [3 hidden]5 mins ago
The escalator failure in 2018 in Rome that caused severe injuries to 24 people was found to be partially caused by safety systems being disabled and overriden because they caused too many false alarms.
fix the alarms? I only had one false fire alarm in my life. and thankfully zero real ones. it's possible.
do fire drills? if alarms get ignored, and you can't reduce the false-positive rate, then introduce fake alarms and monitor the response?
whycome [3 hidden]5 mins ago
Then what? In this case, Suspend the train engineer? The company itself is incentivized to ignore the warnings to keep things on track.
(...on track)
eastbound [3 hidden]5 mins ago
A really important strike that Spanish pilots should do, is striking by respecting the red lights and refusing oral overrides. Hours of delays the first day, trains at the wrong place in the evening, we'd see exactly which regions are affected, and either we agree to repair things or we just leave trains to rot at the red lights rather than risking 900 people's life again (x2 trains = 1800).
> That’s why people here, when they hear the fire alarm they just wait for it to go off
This literally happened to me last night, I was having dinner at my apartment, and suddenly I start hearing a smoke alarm, but not quite inside the apartment, I just kept having dinner thinking "bah, someone probably burned a toast".
Then it wont stop, I walk to door and hear people talking, still don't bother enough, wait a few minutes, then go out and my neighbor said "there are three fire trucks down there, I think it's a real one" hahhaha
The hallway was kind of hazy and smelled like burnt food, for sure... so I just grabbed my laptop and went out hahaa.
D-Coder [3 hidden]5 mins ago
My apartment has both a local fire detector and a building fire alarm.
The building fire alarm is soooo loud and obnoxious, you _want_ to leave the building at speed. (Which I think is the right way to do it.)
avereveard [3 hidden]5 mins ago
Because they don't get held responsible enough for bypissing procedures. Some system are too complex for fully automated operarions, and the human need to play along.
Safety culture is blameless, but only if everyone plays along.
inglor_cz [3 hidden]5 mins ago
"bypissing procedures"
I know that this was likely a typo, but it is also a genuinely great word for the sort of attitude related to these situations.
tintor [3 hidden]5 mins ago
Issue and enforce fines for every false positive alarm, and problem will solve itself.
kazinator [3 hidden]5 mins ago
Or, how about, issue a mandatory repair order and follow-up inspection for every false positive alarm that appears to be due to equipment failure. The follow-up inspection checks that the alarm has not simply been disabled.
IAmBroom [3 hidden]5 mins ago
In a modern passenger rail control system[0], ignoring the warnings results in automated responses like dumping all the hydraulic pressure, setting all brakes at once. This will have two effects: (1) the wheels will slide on a fixed spot, grinding a flat spot, and (2) the operator will either require central control to remotely release the emergency brake state, OR the operator will have to continue at the safest (lowest) speed.
What I'm saying is: false positives should not be ignorable, and modern systems take that choice away (at least, just before the situation becomes unavoidable in worst-case analyses).
That being said, previous fatal accidents in Spain's high-speed rail have resulted in "primitive" uncontrolled areas between controlled areas. Those SHOULD NOT exist. You are essentially saying "lives don't matter that much here " ($/life).
[0] I work in rail safety.
esafak [3 hidden]5 mins ago
Improve your alarms. Duh. You just have to care. Now that people died perhaps they will pay more attention.
electroweak [3 hidden]5 mins ago
I think aircraft are so safe in this regard because, essentially, they are required to use a single international collision avoidance system that is well defined. And modern cars have AEB systems built by vendors aiming for commonality to meet worldwide rules.
But train traffic systems seem to be a hodgepodge of different systems, perhaps locally grown and driven by the local vagaries of politics and rulemaking.
What a surprising inversion of expectations regarding safety.
djankauskas [3 hidden]5 mins ago
The newest signaling systems, ETCS and related sibling CTCS, are quite standardized and interoperable across international borders, so this is an area the EU especially has been making big strides on.
Zigurd [3 hidden]5 mins ago
I'm totally not on the spectrum so I've only watched about 80% of the Plainly Difficult channel on YouTube, but if you want a painless and entertaining, if you're into that kind of thing, way of learning about train signaling and safety, and how safety systems have evolved, I highly recommend it.
>In one recording, the controller tells the driver of the Renfe train to disconnect and reconnect the LZB mechanism that monitors train speeds, and then resume the journey at normal speed.
Wait, I thought Spain's high-speed rail network was all ETCS L1 or even L2?
germandiago [3 hidden]5 mins ago
The main problem comes from under maintenance. I am spanish, we have known this for years.
15 or 20 years ago when I took the train it worked well.
Now there are more trains and they increased the traffic like by 70% if I am not wrong and the budget for railway infrastructure by only 17% and it seems to not scale well enough, for whatever reason I do not know all the details.
There are a lot of railway tracks that are not in good state so speed must be lowered. There are incideents and delays routinely, all the time.
This did not happen until like 10 years ago and it has gotten worse and worse since then, not only in high speed trains.
The roads is a mess also: 52% of infrastructure for roads has bad or very bad defects in it.
The thing is that we have a record in government incomings and the services, ALL of them (healthcare, roads, infrastructure...) slowly collapsing.Part of the money is not going to the right places. I think that nearly 40% of the budget goes for retired people. We have 9.5 million pensionists in Spain.
We have to change that system and rationalize government spending and welfare or eventually everything will collapse.
Grombobulous [3 hidden]5 mins ago
I’m very wary of finger-pointing like your comment that ultimately serves to advocate for cutting quality of life for citizens.
Roughly 31% of Japan’s budget goes to social security. They don’t have problems keeping their high speed trains safe.
Cutting pensions won’t make trains safe.
I will also point out that on its own without further context, a high percentage of government spending going toward something doesn’t make that spending irresponsible or misappropriated. In the United States, a very high percentage of federal taxes are spent on Medicare and Social Security. But it should come as no sirprise that a very large percentage of federal income tax revenue is directly appropriated to pay for those things.
Al-Khwarizmi [3 hidden]5 mins ago
Pension expenditure in Spain is out of proportion from any point of view, though. I'll provide links to some graphs because I think they give more information than my words could:
So yes, the reason why we are underinvesting in pretty much everything is basically pensions. GDP is up, tax collection is up, debt to GDP is sligthly decreasing... but pension expenses keep growing at a fast pace so there's less and less money for everything else. And I say this with both of my parents earning the maximum pension, so I don't have an axe to grind, but it's just reality.
germandiago [3 hidden]5 mins ago
I am not suggesting cutting down pensions. My own parents are pensionists... so that you get an idea.
I am giving an objective explanation in all honesty: Spain needs a pensions reform probably at some point bc it is 40% of the expenses in the yearly budget, with a deficit and a demographic deficit. This will explode.
If it can be taken from elsewhere, better.
But you know how much are pensions in Spain and know our pension system in detail (it is literally a Poncy system...)? They are often higher than people working!
Whether we like it or not, we need to reform or collapse in the future. I wish it could be taken from elsewhere, but 40% is a lot...
There is a lot of useless expenses in public work in our "federal system" (comunidades autónomas).
pofferfish [3 hidden]5 mins ago
You will notice that 31 is less than 40
LtdJorge [3 hidden]5 mins ago
We're financing pensions with debt, that's why it's a problem.
square_usual [3 hidden]5 mins ago
Japan is a terrible comparison here because their rail network is privatized. They're also paying their pensions with debt, and their economy is really stagnant and not a shining example of a country doing well with a pension burden that high.
Grombobulous [3 hidden]5 mins ago
I don’t know why that makes them a bad comparison, anyone can follow what Japan did with its train system.
qurren [3 hidden]5 mins ago
> They don’t have problems keeping their high speed trains safe
Their trains are safe, but they also have 2X the national suicide rate as Spain, which amounts to about 17000 more deaths per year. I'd attribute a big chunk of that to their work culture treating people like machines, whereas Spain's work culture tends to lean towards treating people like humans.
That isn't an excuse for railway mishaps, of course, but I'm just trying to de-romanticize Japan as some kind of magical perfect place. It's not. They might have gotten their railways right, but they have massive safety issues around mental health.
nbajka [3 hidden]5 mins ago
> Spain's work culture tends to lean towards treating people like humans
You clearly have not worked for the average Spanish employer.
xorcist [3 hidden]5 mins ago
Not saying maintenance isn't a problem, it probably is. It's a problem everywhere in Europe. Have you seen train service in England, Germany or Sweden? Absolutely terrible, compared to just two decades ago.
But under-maintenance causes trains to stand still and be late. It does not cause them to crash.
Crashes are caused by running at speeds higher than the (under-maintained) rail can support, or (against all rules and every regulation) no cap on speed when the signalling system is down.
The latter can not be solved with more money and resources. It is a culture problem. Rules can not routinely be disregarded for arbitrary reasons, especially not when they are completely in line with common sense.
rwyinuse [3 hidden]5 mins ago
Over here in Finland our road infrastructure sucks too, and pensioners take lion's share of all the resources. Yet our trains aren't crashing. There's something wrong with systems and safety culture in your railroads. Bad maintenance doesn't cause trains to crash into each other if proper procedures are followed.
Still I agree, pension systems in most EU countries are unsustainable.
JaumeGreen [3 hidden]5 mins ago
Deterioration started long before that, according to my sources it started on 2008, but yeah, last 5 years or so it has gone worse. The budget for it has been increasing year by year. It seems that the main problem is not just lack of maintenance but that there's more traffic and new construction.
Pensions is 13%PIB which is on the European median.
The problem is demographic. Also take into account that retired people have paid for their retirement.
Your rhetoric is not what I'd like to be promoted as the first answer entering. Just reading the title of the news I knew what kind of messages I'd see promoted.
nbajka [3 hidden]5 mins ago
>Also take into account that retired people have paid for their retirement.
No, they have not. It's a pyramid scheme. Whatever they put into the system when they worked probably doesn't even cover 5 years of retirement.
I still don't know why the train drivers don't have a simple data:
The distance to the train that is next in in that railway in its direction.
With this information, that accident will have never happened.
amiga386 [3 hidden]5 mins ago
Signalling systems are never simple.
The LZB system, which broke down, had the data you describe. It knows when trains pass over fixed sensors so it computes where they are, and sends data packets to specific trains informing them their current speed limit, and the next, and how far away that is. If the driver won't slow down, the train will.
When LZB broke down, they had to switch to their other system, BSL (fixed block signalling: https://en.wikipedia.org/wiki/Automatic_block_signaling). You can then know the distance to the next block, and if it's occupied or not, but not where the train is inside the block. You can only guess.
In the next few days we'll likely find out if the control centre also fucked up the block signals...
bgnn [3 hidden]5 mins ago
I'm wondering why don't they use GPS as a redundant data source too.
ironman1478 [3 hidden]5 mins ago
If it was so easy then this never would have happened.
maxglute [3 hidden]5 mins ago
There's like 100s location data on each train, do they not just have a map of where all nearby trains are.
bell-cot [3 hidden]5 mins ago
General case, it's not that simple. Say there's another train a mile ahead of you...but it's on a siding. To compute the effective distance, you'll need to know the positions of the switches connecting the main line to that siding. And switch positions can change far faster than you can stop, even if the other train doesn't move.
rimeice [3 hidden]5 mins ago
Off topic I know but, the BBC has adopted this clickbaity title pattern of “what we know so far about x” for the last year or so and it really jars me. Especially when x is very serious and involves people dying. It’s like an amateur tictoc’er is in charge of headlines at the moment.
dogscatstrees [3 hidden]5 mins ago
Is there an international consortium for best practices in high-speed train control? Surely there are countries that have good systems in place, or have benefited from knowledge-sharing. I have to believe these train systems were built with outside help and then organic improvement or the opposite. Spain, talk to them.
iSnow [3 hidden]5 mins ago
The issue (at least in Europe) is that there are too many historical train control systems. There are more than 25 different, non-interoperable train control systems currently used across the European rail network.
That's where the EU came in and developed ETCS (https://en.wikipedia.org/wiki/European_Train_Control_System) as a modern alternative. Unfortunately, the EU doesn't have the legislative power to force member states to adopt it and also not the money to bribe them. So ETCS is still competing with the legacy systems.
However, the reason for that crash apparently was the dispatcher who greenlit the cab driver to go full speed ahead after the train control system on that track had crashed even though they knew that another train was reporting that it was unable to restart and get going. Procedures in case of a train control outage are clear: all trains can only move at a max speed of 40Km/h - slow enough to drive and brake on sight.
Instead, that train crashed into the stationary one coming from 200Km/h
djankauskas [3 hidden]5 mins ago
There's definitely international communication, LZB is a German signaling system and the intended 40kph speed limit after system restart is common across Europe.
satellites [3 hidden]5 mins ago
Japan has had high-speed trains since the 1960's and have had zero passenger fatalities. They must be doing something right.
steelframe [3 hidden]5 mins ago
This event was pretty chilling for me because I just took the Renfe line from Seville to Madrid a couple of weeks ago while visiting Spain. I generally like to think that I have a pretty good instinct on relative risks and make reasonable decisions based on that. This time around, between the incident earlier this year and this most recent incident, depending on how you interpret and apply the statistics (of course that's always up for healthy debate), it looks like it would have actually been safer driving between Seville and Madrid. That's a pretty low bar in terms of safety!
I set my favorite agent on the task (Opus 5.5 in the Kagi Assistant), and given the two rail crashes in Spain this year, these are the stats it came up with for "chances of dying" via various modes of transportation between Seville and Madrid:
* EU high-speed rail, long-run average: ~1 in 36 million
* This rail line, counting both 2026 crashes: ~1 in 400,000 to 1.2 million (prior to the most recent crash it was 1–3 million; now ~2.5× higher)
* Flying with a European airline: ~1 in 80 million
* Driving: ~1 in 1 million or worse
Of course this is hindsight. Heightened awareness of risks, higher propensity to overreact to anomalies or alarms, procedural changes, and so forth in the wake of this second crash might push high-speed rail in Spain to be higher than the European average in the future.
loloquwowndueo [3 hidden]5 mins ago
Ask it to look for high-speed train crashes globally over the past 15 years (to include the 2013 one in Spain as well) to be honest I don’t remember any HS accidents other than the three in Spain so, odds or not, I am NOT taking a high speed train in Spain ever.
absoluteunit1 [3 hidden]5 mins ago
This was a terrifying read because I initially read about this at the air port in Madrid after taking a Renfe train from Alicante; literally at the same time...just a different line
enriquto [3 hidden]5 mins ago
it's a matter of budget and political will. Spain simply cannot afford all these train lines, and the system fails. But hey, we have high speed train between Villacojón del Caudillo and Cagalera de la Reina, because they happen to be aligned to the center of the country (Madrit). These railways make no economical sense, they were built for political reasons, to support a "radial" concept of the country that does not really exist yet.
Meanwhile no high speed rail between València and Barcelona, because that would somehow erode the power of the central elites.
Yokolos [3 hidden]5 mins ago
So based on this, the safest place to sit is presumably the middle carriage?
I would actually sit in front now. Sometimes you would be able to still get vital information and being actually able to act. But the safe decision would be no to enter the train.
flohofwoe [3 hidden]5 mins ago
> But the safe decision would be no to enter the train.
You might just as well never leave your bed, that's even safer ;) Train travel is much safer than travelling on roads, and in the same ballpark as commercial flight.
barbazoo [3 hidden]5 mins ago
> Sometimes you would be able to still get vital information and being actually able to act.
Optimistically assuming you have a minute to react (I'm imagining closer to 10s), what could one possibly do?
1718627440 [3 hidden]5 mins ago
Yeah, I would also guess about that time. Run away, jump out of the train, duck behind some larger wall, pray.
comrade1234 [3 hidden]5 mins ago
That's where the bus hits you.
ktallett [3 hidden]5 mins ago
I can't imagine what every passenger who survived and the families of those who passed are going through. Such a catastrophic incident with multiple human failures is so tragic and so needless. From the controller to the driver, every single one of them should have said hey we shouldn't just ignore a signal and should investigate why it's on first. For this to be such a quick decision suggests it's not a one off. I would be extremely interested to see how many near misses or ignored signals there has been across Spain. The crash earlier this year was due to inexperienced workers and it seems as if significant training improvements and protocols are needed.
jplrssn [3 hidden]5 mins ago
If as a driver you get told by the control centre to get the train moving again at maximum line speed, surely you should be able to trust that it is safe to do so?
I don't see how this would fall on the drivers at all.
gpvos [3 hidden]5 mins ago
My thoughts as well. It appears that such signal failures happen so often that the controllers regularly let trains run through red under verbal authorization. I don't know the exact protocols, but I would expect a driver to ask for confirmation, as happened here, and then trust the control centre. However, there is clearly a huge systemic problem, with added complexity for the controllers, and there should at least be double checks in the control centre.
1718627440 [3 hidden]5 mins ago
The person who controls whether the light shows red or green and gives verbal authorization is the same. It's both a tool, to transmit the same information.
pixl97 [3 hidden]5 mins ago
Same information, no.
A person saying you have a green light when you have a red light is not the same information at all. The probability that something has gone wrong and will lead to disaster is many many times higher.
1718627440 [3 hidden]5 mins ago
That's also true, but you should also be able to trust written movement authorities, otherwise why have them in the first place?
crote [3 hidden]5 mins ago
Trust but verify. You wouldn't drive your car into a lake just because your satnav tells you to, would you?
As we also know from the aviation industry, controllers are human and therefore will make mistakes. A controller shouldn't issue a wrong order, but a driver also shouldn't accept an order they aren't certain about, and there should be technical systems backing both sides of that up.
It doesn't "fall" on the driver, but it doesn't "fall" solely on the controller either. It's a systemic issue, and many pieces have to fail for a disaster to happen.
gus_massa [3 hidden]5 mins ago
You can't verify, the rail has curves and other stuff that block sight.
Also stopping distance for trains is huge. This video for high speed trains says 5km (3mi) https://www.facebook.com/Renfe/videos/%EF%B8%8Fcu%C3%A1l-es-... That is probably at full speed, but IIUC the accident was at half speed so the distance should be like 1.2km (0.8mi).
1718627440 [3 hidden]5 mins ago
> As we also know from the aviation industry
The aviation industry operates like the railway industry ~1920 (somewhat by necessity).
> You wouldn't drive your car into a lake just because your satnav tells you to, would you?
You are assuming a train driver is equivalent to a car driver. He's not, the analog would be more a repairmen that you always take with you on journeys.
bigDinosaur [3 hidden]5 mins ago
To have had this many incidents compared to other HSR networks around the world gives all the signs of a classic case of normalisation of deviance.
Sadly we'll probably watch a lot of individuals being blamed/scapegoated for systemic issues, but hopefully even Spanish politics can organise a proper investigation after this many deaths in a single year.
1718627440 [3 hidden]5 mins ago
> From the controller to the driver, every single one of them should have said hey we shouldn't just ignore a signal
A train driver has zero insight in what is going on and where other trains are. They do need to trust the orders they get, if you want to question every order you will never start to drive.
AdrianCX [3 hidden]5 mins ago
The train driver's job is to say: "it's red, I'm no moving, not my problem, you make it green if you want me to go"
That's why it's a union job
Also he's the first person to die on accident so it's that and the safety of everyone else
They do not 'need' to follow others, they just need to refuse unless all safe and green.
If they never start to drive it's the companies problem to deal with angry non-dead customers
stevage [3 hidden]5 mins ago
That is not how the procedures work, so the driver would be fired as soon as they did that.
Every train network has situations where drivers are authorised to proceed against a red signal. Not usually at full speed though.
AdrianCX [3 hidden]5 mins ago
They wouldn't get fired. They are protected both in the US and Spain.
At most face unlikely discipline.
Here they would even have valid reason to refuse - order was given for full speed, regulation says low speed ready to stop.
So a "No, i'm not doing that, you're moron" would be justified.
1718627440 [3 hidden]5 mins ago
No, he would get fired, because that's not his job. It would be like the machine engineer on a race track refusing to fix the ignition, because somewhere on the track he doesn't see, the asphalt might be broken.
kube-system [3 hidden]5 mins ago
Do train conductors not have the final authority in safe operation the way airline pilots do? If so that is absolutely insane.
1718627440 [3 hidden]5 mins ago
The equivalent is a tower telling a pilot they should land and the runway is clear, except it isn't. And there also being fog, so you can't see it before it is too late. And you can magically not veer of. Planes can go around in three dimensions and try to rise again, a train basically moves in one direction, if they see the problem, it is way to late.
There is no point in the train driver making a decision about where the train goes, because he has no information for that decision. Hence it is also not his job. Like, yeah if he has reasonable reasons to think there is something wrong, nobody is going to fire him, but what is the policy that allows him to do so, while not just randomly deciding to not drive today? There is no difference for him, until he is about to die.
kube-system [3 hidden]5 mins ago
Pilots have the final say to refuse or stop a flight for any safety reason of their judgement... even if others tell them it is safe. And they are protected not by policy, but by law in doing so in the US and most countries.
1718627440 [3 hidden]5 mins ago
But they also have the means to do so. If a train driver has a reasonable doubt about safety, nobody is going to punish them. But there is simply no way the doubts are reasonable, so it becomes just randomly doing otherwise, at which point the question is asked whether you are fit for the job.
kube-system [3 hidden]5 mins ago
I fail to see how following normal safety protocol of proceeding at 40km/h would have been indefensible or unreasonable? They are the rules of operation for this scenario and exist for the exact reason we are reading this story. I can’t think of anything more defensible than “I am not going to break safety rules”
Never would a pilot be reprimanded for refusing an ATC order to move their plane in a way that violates established protocols
1718627440 [3 hidden]5 mins ago
I don't know, because there is no actual proper safety report yet. That certainly sounds reasonable, but obviously the dispatchers though otherwise. Likely because they did not actually understood that there was a problem, but that it's just that annoying bug again.
pixl97 [3 hidden]5 mins ago
>No, he would get fired, because that's not his job.
Then what the fuck is this country even doing with trains.
No, no no, no no no.
Interlock safety systems exist for a reason. In any safety system where the interlock is down you do not resume standard operations. Ever. Why, because there is a book with blood that is 10,000 pages deep that describe the horrific accidents that happens when you do. Might as well be an axiom at this point.
>because somewhere on the track he doesn't see, the asphalt might be broken.
Again, stay away from analogies and safety critical systems.
The person behind the break and speed control of the train is no different from the captain of the airplane or the captain of a ship. They have full authority control to stop the train and refuse to move it until they are sure of the safety conditions. Any attempt to fire them should result in an immediate stop work from every employee in the system until they are put back on the job and the safety concerns are resolved.
1718627440 [3 hidden]5 mins ago
> Then what the fuck is this country even doing with trains.
That has nothing to do with a single country. Above 40km/h you are not allowed to drive on sight in a lot of countries. I don't know how it is in Spain, but in Germany, you are also not allowed to drive via track-side signals above 160km/h. You can simply not decide about where it is safe to go from inside the train.
> Interlock safety systems exist for a reason
Yes, and that's a job of the dispatcher, not of the driver.
> In any safety system where the interlock is down you do not resume standard operations.
That might be nice in theory, but that has not much to do with reality. There is simply always something broken. It doesn't even need to be a signal, way more often a crossing doesn't properly report that it is closed.
> The person behind the break and speed control of the train is no different from the captain of the airplane or the captain of a ship.
Nah, it's very different. For one a captain or pilot can control the direction of the ship/plane. They can also determine whether their operation range is clear. A train driver can do none of these things. What's the point of making them responsible for safety if they neither have the knowledge, nor the lever to change things? Trains are more secure, because the driver is not responsible for the infrastructural safety, not less. That includes whether the track is clear or not.
knottn [3 hidden]5 mins ago
So it’s clearly an industry wide problem then. The more I read the more thankful I am California can’t build high speed rail.
The point of this discussion is that people blame the train driver or say "use self-driving", when that is not going to solve the problem, because that's not where the error is. The error is not there, *because* for rail making errors operating the train is not going to cause an accident (most of the time), which is not the case for cars.
ktallett [3 hidden]5 mins ago
The driver always has the final say on whether the train is safe to move. They are not just a button and lever pusher. They have to analyse whether the decision is correct. Hence why I stated there were multiple points of failure. The controller and the driver both went with full speed despite it being completely against regulation on a red signal.
1718627440 [3 hidden]5 mins ago
> They are not just a button and lever pusher.
I agree. But the decision whether all switches are locked in the correct position and that the track is clear, is not one that he is supposed to make and he also doesn't have the information for it.
> The controller and the driver both went with full speed despite it being completely against regulation on a red signal.
Going full-speed in the case of a red signal is not necessarily against regulation. Also the information of "red signal" or "you can go" is both a signal from the same source. There is no information for the driver to make a different decision over the dispatcher.
I can't comment about whether the current accident was caused by going against regulation, and more important by whom and against which. We need to wait for the proper safety report, not for a BBC article. If you take the latter at face value, it would mean there are clowns operating, which I am sure, is not actually the case. The real error is always way more subtle, otherwise it would not have happened.
1718627440 [3 hidden]5 mins ago
> The train driver's job is to say: "it's red, I'm no moving, not my problem, you make it green if you want me to go"
A written movement authority is a signal as well in railway terms. It's more like "I don't trust your second traffic light, that you placed next to the normal one, because the normal one is broken".
dutchbart [3 hidden]5 mins ago
The even more insane thing to me is that the controller knew that there was another train in that block, knowing it was no signal failure. The driving train should’ve never been commanded to continue on full speed by the controller.
cedws [3 hidden]5 mins ago
Trains shouldn’t even be manually driven in 2026. We have self driving cars now which is a way harder problem to solve. Relying on a system of signals and driver attentiveness is archaic.
delta_p_delta_x [3 hidden]5 mins ago
> Trains shouldn’t even be manually driven in 2026
Potentially, but the point is that signallers should physically be unable to allow trains to proceed, and drivers should physically not be able to override them. British signalling from the 1800s has physical interlocks; this isn't a matter of manual versus automatic train operation. It is clearly systemic.
M95D [3 hidden]5 mins ago
How do you pass a defective signal then? How do you couple a second locomotive? How do you add cars?
kube-system [3 hidden]5 mins ago
Yeah, if you completely ignore availability as a problem. The state of the art self-driving technologies we have today only work in some conditions, some of the time.
The reason vehicles are still driven manually is because humans rely on transportation every day, all of the time.
dns_snek [3 hidden]5 mins ago
Driving a train and driving a car are two completely different challenges.
If signaling worked properly then it wouldn't matter whether the train was driven autonomously or not, the "problem" becomes trivial. Establishing and continuously verifying that signaling is working properly is the hard part.
Without signaling you're limited to crawling speed just like humans are when they don't have any signalling .
1718627440 [3 hidden]5 mins ago
We do not have self-driving cars in all environments that clear the necessary security regulation! Also the socially accepted number of deaths due to trains is way below that for cars. The current accident is just a Tuesday for car traffic. (Spain recorded 1785 road deaths in 2024[1], that's 4.9 per day) Detecting objects (and future objects!) on a train track is still a hard problem.
The current system is basically that the train is driven both automatically and by a professional attentive driver at the same time. Changing it to just the automatic system is going to reduce safety. Also the real world is way to messy to reach acceptable availability rates with only automatic systems.
> Detecting objects (and future objects!) on a train track is still a hard problem.
In this case the “object” was another train. That’s not the “hard” part of the problem. This sounds like an apologist comment.
dns_snek [3 hidden]5 mins ago
What difference does that make, genuinely?
Are there systems that can warn drivers and prevent collisions without external signaling, like ACAS?
1718627440 [3 hidden]5 mins ago
Yeah, that's a solved problem. Did you even read my whole comment? I answered why "just use the system from self-driving cars" wouldn't work and in fact would be less safe than the current system.
AnimalMuppet [3 hidden]5 mins ago
What's the stopping distance of a high-speed train at full speed? I don't know, but I bet it's kilometers, not meters.
Detecting an object on the tracks 2 km away (say), as opposed to beside the track at the same distance, is in fact a hard problem. The tech used in self-driving cars is not going to solve it.
It's incredible the minister didn't resign after the January crash and I doubt he will now either. I understand that perhaps the problem started in the control centre but surely at the end of the day the minister is responsible - they don't get paid a fortune just to pass the blame on to the workers.
Xenoamorphous [3 hidden]5 mins ago
> they don't get paid a fortune
Salary for ministers is around 80k euro per year. Yes significantly more than the minimum salary but hardly a fortune.
logicchains [3 hidden]5 mins ago
The average salary in Spain is around 30k euro, and almost nobody makes 80k there.
baal80spam [3 hidden]5 mins ago
> The average salary in Spain is around 30k euro
I could not believe it, but it is actually true:
The average gross annual salary in Spain is €29,540, which translates to approximately €2,461 per month before taxes.
agarsev [3 hidden]5 mins ago
I fail to see how the two accidents, which seem to have very "down to earth" explanations (maintenance failure by workers, protocol override by operators) are being assumed to be a political responsibility so quickly by some and asking for the minister resignation. Now, two in a row seem to point to systemic issues. Is this responsibility of Adif or Renfe? maybe those state companies have to be thoroughly revised. is it due to lack of funding? maybe taxes should be raised, or money diverted from somewhere else (though seeing the spanish budget, it's hard to tell where from, both teachers and doctors are currently protesting for lack of funding). Maybe it is, in the end, a political directive that should have responsibilities declared in the executive. But seeing so many interested parties jumping to that conclusion literally hours after the crash means it's not done out of any reasoning but political animosity
Xenoamorphous [3 hidden]5 mins ago
> are being assumed to be a political responsibility so quickly by some and asking for the minister resignation
It sucks but that's how it is over here. It's "my" party the one in power when a catastrophe like this happens? It's not the politicians, it's someone else. Is it the "other" party? Surely the politicians are ultimately responsible.
This reflects on the news media as well.
pvaldes [3 hidden]5 mins ago
"the collision occurred after one train stopped on the line unexpectedly due to an Automatic Warning System fault causing it to brake. It was then hit from behind by the second train that had passed a red stop signal protecting the stationary train in front"
The train collided rear-end into the rear carriages of the other train and derailed, which also resulted in the three rear carriages of the first train to derail
- This was Białośliwie train collision (Poland) in June 2026
In this last case Police suspected sabotage after a 300 Kg piece of rail was found deliberately laid in the railway.
"A fire was detected in the rear cabin of the high-speed train. Following safety protocols, the 283 passengers on board have been evacuated"
This was an AVE passenger train in the line Madrid-Barcelona, in October 2026. Most probably another case of sabotage.
vagab0nd [3 hidden]5 mins ago
Tell your travel agent:
"Add a global memory. Whenever I'm in Spain or planning to go there, remind me of this: <story url>, and plan to avoid it."
whycome [3 hidden]5 mins ago
Why isn't there basically adsb data for trains?!
They can broadcast speed and position. Other trains can then see things ahead on their track. This seems like a solved problem so I must be missing something obvious.
iSnow [3 hidden]5 mins ago
Two main reasons:
- trains go in tunnels or tracks are between houses. When train control systems were defined in the 1990's, there was no way to make them sensitive enough to record GPS positions. Instead there is a different location system based on so-called balises with a fixed position on the tracks. Every time a train crosses one, it knows where it is.
- Planes go in 3 dimensions, trains in one. If ATC wants to ensure two planes do not collide, they will assign them different headings and/or heights. Precise position isn't that important. Trains cannot avoid each other, that's why they move in blocks.
And yes, they do signal their position back to the control center, it's just a different protocol
jcdavis [3 hidden]5 mins ago
Modern signalling systems are basically adsb for trains. (ETCS is the modern standard in Europe, this line was using the older German LZB). Problem is that they can, and do, fail. And when that happens too frequently (as it seemingly has been in Spain due to a lack of maintenance), its easy to get sloppy on the manual handling
flohofwoe [3 hidden]5 mins ago
Safety systems don't help much when they fail themselves. E.g. usually there are automatic systems in place that prevent that two trains are on the same rail network section at the same time, but this system apparently has failed. Details are in the article.
Here is a plausible alternative explanation:
They’ve probably seen false warnings over and over and overridden them enough times that they lost sense of the risk. They need to keep trains on schedule, using a buggy system, with a manager looking over their shoulder. They override the warnings over and over, nothing goes wrong, and they forget that it may actually be right. Look at the Challenger explosion, Chernobyl, or any other failure like this, and there’s usually a bureaucratic process that has run amok, and the individual is just following perverse incentives that have been socially normalized over time.
So I’ll wait until I have more information before I proclaim this as human negligence and the system doing exactly what it’s supposed to do. We don’t know how often it was doing the wrong thing and confusing the fuck out of the human.
Normalization of deviance,
https://hn.algolia.com/?query=normalization%20deviance&type=...
Negligence is not limited to the single human who issued the order. it's pretty unlikely that their order could have caused this without a significant amount of other negligence that eroded the safeguards. Nevertheless, the negligence is human, not machine in nature.
[0] https://en.wikipedia.org/wiki/Normalization_of_deviance
This isn't a game of Hot Potato where the last person touching it goes to jail for gross negligence. You have to look at it through a Swiss Cheese model: every individual safety layer can and will have holes, but a disaster can only occur when all of those holes align.
Why did the LZB system fail? Why did the train dispatcher use the wrong backup procedure? Why did a backup procedure with zero safety checks even exist? Why did the train operator accept this backup procedure? Why did the train allow high-speed driving under those unsafe conditions?
It does indeed seem like the train dispatcher made a big mistake, but that was far from the only thing that went wrong, and it would be myopic to use him as the scapegoat for a far larger systemic issue.
Someone was driving the train who couldn't estimate the stopping distance relative to speed.
If a car is stalled in the middle of the road, and you hit it, that's on you. 200% if a reflective warning triangle was up 100 meters back.
At least one of the failures here is that the dispatcher authorized such a high speed, in other systems I am familiar with, generally the procedure with a signal fault is to crawl at a speed such that the train can stop in line of sight distances.
In fact, that is the Spanish protocol, which for some reason was bypassed by dispatch even after the train driver had questioned it:
> Under normal protocols, the driver would be expected to continue moving at a maximum of 40km/h according to their line of sight, and not at normal speed on a track designed for speeds of up to 200km/h.
Air travel is as safe as it is because we don't stop the investigation at "pilot error" but instead ask why the pilot made the mistake, and why a single mistake was able to lead to loss of life.
Rough estimate: by car, you can travel from Lisbon to Talinn (4000km) 100,000 times before expecting to die; by train, almost 4 million times, by plane 400 million times.
You are 100% dependent on your safety and monitoring systems because almost every problem that could come up is beyond the horizon of your human senses. Stopping distances are in thousands of feet to miles depending on the train size and weight. Add any curves and that's far beyond your visibility.
Then you add in management complaining that you're too slow and you need to do things faster and cheaper or you'll lose your job. Things turn from solution culture to blame culture.
Then you add in false errors and warnings in a system that teach you to ignore them and an upper management that doesn't fix them.
Then you have the day like hundreds of others where warnings are going off, management is yelling, but this time there is a stopped train around the corner and everyone dies.
This is a systemic problem.
The stopping distance for a train this size and this fast is around 2km. Good luck estimating that by sight. There is a reason the normal protocol has a 40km/h max speed for traveling according to line of sight, which the driver was told wasn't needed.
https://komonews.com/news/local/13-year-old-boy-killed-while...
On a surely unrelated note, car travel is by a substantial margin the most dangerous mode of transport most of us ever use, and the most dangerous activity most of us routinely engage in.
This is just one viable solution out of dozens that anyone can come up with in minutes. The idea that 'we don't know where the trains are' is a thing in this age is absurd and an entirely political problem. You could even monitor it from real time satellite video at this point.
If I can have reasonably accurate gps readings of my phone while I'm on the train, there is zero reason for train companies to not have systems that are at least as accurate.
"Reasonably accurate GPS" trying to determine which track you're on at 150 mph is not as simple as you make it sound. Yeah, it can determine how far along the track you are. But when you get two trains moving toward each other, each at 150 MPH, do you really trust that GPS to tell you that they're on different tracks?
Keeping track of which parallel track a train was on automatically was a solved problem a hundred years ago, using relays and lights and hard-wired logic. Adding computers and GPS greatly increases the precision with which dispatch knows position and speed along the track, but knowing which track has not changed in the last century.
What we're talking about here is some sort of TCAS-equivalent for the case where the central signalling is down – while it's easy to accurately localise trains with the aid of a central signalling system that authoritatively knows about the infrastructure layout, it's quite more difficult when you're trying to do the same thing in a decentralised, train-local fashion.
Single track means that at least outside of stations, collisions can be reliably identified without much danger of false positives (and for station areas you can just institute a blanket speed limit to compensate for the gap in RCAS coverage, which might not even be any lower than the speed limit required for traversing diverging/spring-operated/hand-operated points there anyway), and no already existing full-scale signalling system means that RCAS actually provides a significant safety benefit and is therefore likely worthwhile from a cost-benefit-analysis point of view, too, if you're actually regularly operating multiple trains simultaneously on that kind of infrastructure.
Whereas on multi-track mainline railways avoiding false positives is much harder and normally you should already have proper signalling and train protection systems in place anyway, so the additional safety benefits of RCAS would be much more marginal.
Oh, they can, but it's usually a very traumatic event.
It's not impossible. But handwaving GPS placement of trains at the correct location, direction, and track deserves more than a handwave as trivial.
When Google Maps gets wrong what lane I'm in, nobody dies. It can be right 99% of the time, that's good enough. It's not good enough for a train system, though - at least, I suspect it's not. I'd want a lot more than "it works in my car" before I trusted it.
Forests are irrelevant; rail right-of-way contains no trees, and is wide enough to assure clear "view" of satellites.
No, what I describe has nothing to do with the companies, that's the research state. It's just an indictment of you making bold statement about a subject, you don't now enough about.
> I can have reasonably accurate gps readings of my phone
Would you dare to cross on a rope over a deep valley, blind using only GPS readings of your phone? Because that's kind what you are suggesting, expect you also move a few hundred other people.
Hang on, this is nothing at all like that - trains run on fixed tracks. The only bit of data we are interested in for collision avoidance is the linear offset along the track. Even the shittiest GPS fix of all-time would give a good-enough intersection with a fixed path to avoid crashing into a second stationary train in the open country-side (do you see any satellite line-of-sight blockers in the crash footage?)
So that is naive, but assuming that would be all that you need, with GPS you would also need the positions of all other trains. But why would you transmit all this information to every train, instead of just computing the collisions in a central node? (That's what is done now.) A better fit for what you suggest would be radar, and this does exist. [1] But that's where your original assumption is naive. You regularly pass other trains within <2m at high speeds, so linear offset is not all you need.
Because central nodes can fail (as they did here, both human and machine), and providing this redundant data allows both the computer and the human-in-the-loop on the fast-moving chunk of steel to independently validate the decisions coming from the central node.
> You regularly pass other trains within <2m at high speeds, so linear offset is not all you need.
In this collision, both trains were on the same track. So while we obviously care about adjacency issues in the general case, this specific failure mode can be detected purely via a linear offset.
> In this collision, both trains were on the same track.
Yeah, but how do you distinguish that? So when I understand you correctly, what you want is: Find another moving chunk of metal in the radius of 2km, which moves toward you, but not in a direct or ballistic trajectory, but in a arbitrary complicated trajectory, but which can lookup in a database. Also you are operating in the real world, so there are potentially houses, trees and mountains in between. I guess that would be possible, but it would be really expensive. Your best bet would be to adapt a missile detection and targeting system from the military. A system which does exist and is somewhat similar is RCAS (https://www.dlr.de/en/kn/research-transfer/projects/next-gen...).
By enumerating the tracks?
I feel like you are intentionally trying to turn this into a spherical cow situation by insisting on solutions that work in an information vacuum. All of this sort of problem in the real world is solved by sensor fusion from multiple data sources.
Trains are captive to a particular track - they can only change tracks at specific pre-determined junctions. With a pretty minimal sensor feed from each junction we can statically determine which track segment a given train is on. With GPS we can shrink that segment length down to a few kilometres. By sharing data persistently every single train can validate that central command-and-control is not about to run it into another train from behind...
There cases which are genuinely challenging engineering problems (i.e. derailments that impinge on adjacent tracks), but this trivial case of bumper cars is not one of them.
> By enumerating the tracks?
How do you distinguish that the <2km away detected moving train runs on your track on not on the one directly besides you?
> Trains are captive to a particular track - they can only change tracks at specific pre-determined junctions.
Yeah, but you do not know which one it runs on. Your entire point is that you do not trust the information the infrastructure knows. If you do allow to use information from the infrastructure, then why not use the sensors that already exist along the whole train network? It's also very unlikely that there is something electrically connecting the two rails of a track, that you would like to run over. So why wouldn't you trust that information, but some vague GPS signal?
> we can statically determine
But the current state of the art is, that you deterministically and provable know where a train is. Why would you use a more expensive, less safe system? The current focus to reduce errors in computing train conflicts is to prevent random bit flips due to radiation at the same time in three different computers running different software.
> I feel like you are intentionally trying to turn this into a spherical cow situation
The situation where you proposal makes sense, but the current system does not, is a spherical cow situation, that's my point.
You are the one who framed this conversation as it not being solved how to deterministically know where a train is. Everyone else in here has been kindly suggest that if perfect information is unobtainable, then we should work with what we have
> Trains are still not able to assess properly where they are, even using satellites and inside train sensors. Of course there is research on that, but it's still an unsolved problem.
*Trains* on there own! This IS a hard problem, how to do that with any other infrastructure. It IS current research and not yet solved. That is for example relevant, if you want to be able to run trains at full speed <1m tolerance, so that you can have more than one train stopping at a station <60s. All while still not paying for infrastructure and maintaining backward compatibility with a century old trains. (I mean in the future you could use the same to also couple trains at full speed, but that's still sci-fi.)
...is that something you'd ever want? In general, it is, but the way it's handled is by having those trains stop on separate tracks.
Running multiple trains through the same station track in under 60 seconds means that all passengers must embark and disembark in under 30 seconds. That's very tight. I would venture to say it's too tight and meeting this goal would make the trains worse.
(And if passengers aren't getting on or off the train, then the train isn't stopping at a station.)
> Safety critical systems need to work 100% of the time
Railway safety must be safe 100% of the time, but not available 100% of the time. Also the point of a signal box is to make decisions about the order of train assignment to track. You absolutely do not want multiple points of truths for that.
There are optimizations possible like make segments smaller etc but the original algorithm is trivial. If we can't figure things out, we make segments longer and we slow down the trains until we can. I am positive for a sufficiently large track segment and a sufficiently slow train, we can always answer the question with a no.
https://en.wikipedia.org/wiki/Railway_semaphore_signal
https://en.wikipedia.org/wiki/Interlocking
>Even GPS + Starlink + 1 monitor (is that 50k€?) could have prevented this.
My reading on that sentence was that even a simple setup would have been sufficient to prevent this. Not that it should be the only thing.
- I don't think X would actually work, without actually eventually recreating part of the current railway control system, and the current rail control system alone already works better.
- I don't think another less reliable more costly safety system helps, when the current one already stated that there is a problem, and it was ignored.
Throwing up our hands about how hard a problem this is seems like a ridiculous position to stake. If we can design self-driving cars, that operate safely in far less controlled environments, we can figure out the linear offset of a large vehicle traveling along a physical rail running along a fixed pre-determined path.
Self-driving cars aren't supposed to drive quicker than they can look ahead, which makes the problem way easier because you don't have to figure out how to detect obstacles ahead of time and can simply rely on vehicle-local information to stop if necessary. And because cars can brake way more rapidly than trains, it means you can still drive reasonably quickly even within that limitation.
Plus in an emergency, cars have steering as an additional degree of freedom to attempt getting out of any nasty situation that may have developed.
(And of course the socially expected safety standards for cars are quite a bit lower than for public transport…)
Trains on the other hand have braking distances on the order of a kilometre or so, and high-speed trains at full speed several kilometres, so trying to get by on local data only is hopeless and the usual strategy is instead having central signalling system that can accurately track trains and coordinate their movements.
> If we can design self-driving cars
We can not design self-driving cars to the safety standard that is required for railways. They are way less safe than the current half-manual system for railways. What you suggest is using less automatic safety systems than what we currently do.
I don't think that's relevant to trains. Cars can avoid a collision much more easily than trains can. Cars can swerve, and if they are at a distance at which line of sight tells them they will hit an obstacle, they are moving slow enough to stop before hitting that obstacle. Trains have to stay on tracks, and they need up to 4 kilometers to stop moving.
The constraints are very different, so the solutions and tradeoffs will be different too.
Current operation of a train is basically self-driving and supervising driver. So if you suggest "just use self-driving", you make the system less safe, not more, because it means just getting rid of the human supervisor. This is not currently done, because it would be too insecure. It might be done in the future, but rather because less safety is going to be accepted in favor for getting rid of the costly human.
A self-driving train will happily cause a crash, if the target is "drive with high-speed in that segment currently occupied by another train". The issue is that that becomes a target, not that there is a human in the loop.
Sure, if you allow trains to ignore safety completely, then accidents will occur. That is a ridiculous statement.
But there was a recent incident in Germany as well (https://en.wikipedia.org/wiki/Burgrain_train_derailment), which is somewhat similar to the earlier accident in Spain this year. Targeting high value projects, while not paying for proper maintenance is not something that only happens in a single country.
> but you can't say that it has ever happened in Japan.
That sounds very unlikely to me, and in fact Wikipedia indicates otherwise: https://en.wikipedia.org/wiki/Shigaraki_train_disaster
It's a mixed bag. That can also cause safety violations, they were suicidal incidents, because punctuality is placed over safety, in Japan. https://en.wikipedia.org/wiki/Amagasaki_derailment
That is completely false. PTC does that, and we've had it for several decades. There are several self-driving cars operating in the world right now. I have never heard of a PTC system causing accidents; those occur in places where the system isn't required (like entering Grand Central).
You keep pretending that avoiding train collisions is too magical to achieve with current tech, but train traffic is easy to limit (but slightly harder to optimize), and systems exist to do that, because rail is unique amongst all forms of travel: if you drop speed to zero for any trains at risk of collision, they are safe. Planes will plummet; most cars are human-operated and you can get rear-ended, etc.
And they somehow work with radar, lidar and GPS from inside the train? No they work with classical block based systems and on signalboxes. So all the safety systems are outside of a train.
> You keep pretending that avoiding train collisions is too magical to achieve with current tech
Huh?? Railway interlocking exists for more than a century. It's very safe and I didn't wrote anything contradicting that.
And some problems are just _open_ to outside looks. My assistant tells me that the room for error in trains on one dimension ('left - right') is mere 10s of centimeters. I understand that problem. But what track you are on, isn't that obvious to the human in the cabin? (Again, simplifying, not flaming. Production ready safety is _hard_.) So could a vision based solution help count tracks from left to right? (Assistant: "US PTC, on about 54,000 route-miles, uses GPS for the lead locomotive plus crew-entered track information and switch position".) So you use the dimension that matters most in crashes (forwards / backwards) from satellite, augmented with vision or human based left-right positioning. Some trains already have sensors to sense things like leaves on the track to adjust speeding and braking... So the sensor based approach is already there.
Perhaps I am read as suggesting that the problem is easy, and that is not my intention. But for cars this was solved decades ago for routing and years ago for self-driving. I use that daily. Flying is organised with a very clear 6 sigma approach. Crashes are nearly always situations where events / risks stack. Trains (in Spain)...?
Tl;dr - Safety is a function of (human; process; technology) and there is clearly something lacking for trains, when compared to other types of transport.
> Would you mind sharing some more of the why it is still an open problem?
Because for train sensors, there is a small drift which accumulates too much, hence it is synchronized by magnetic position markers in the tracks.
> I understand satellite positioning isn't definitive
Yes, and the point is it might be some solution if we would have the safety systems from 1860. But we do not and hence it needs to be more accurate than the current system, and it is not and in addition also more expensive (and subject to remote influence and reliance on potentially adversary nation states).
> Sorry for the bleak introduction of economics
No, economics is basically the primary constraint for safety. We could pay million people to make sure a single person does not stumble if we want total safety, but that's completely pointless, and also these million people would starve, because no one is producing food anymore.
> But even as a tertiary or lower risk mitigating factor
But for that it's too expensive and still unreliable. There is RCAS[1], which I already linked elsewhere in the thread. That's basically cutting edge and too expensive to introduce everywhere. Also previous safety systems are already not rolled out enough, which is causing these accidents, so rolling out yet another expensive system is not going to improve much.
> But what track you are on, isn't that obvious to the human in the cabin?
Yes, but if it is already known, why use GPS to calculate the same information with more error?
> So could a vision based solution help count tracks from left to right?
If the train driver or dispatcher makes use of vision to assess the train position, the error will be higher than the current sensor/electric-resistance based system.
> Assistant: "US PTC [...]
BTW, that seems to be a verbatim quote from https://www.railwayage.com/cs/the-way-forward/
> US PTC
According to Wikipedia, ASFA being introduced in 1975 is rolled out in the entire Spain network. ETCS which is the European standardization seems to be rolled out on all high-speed lines or currently being rolled out.
> So you use the dimension that matters most in crashes (forwards / backwards) from satellite, augmented with vision or human based left-right positioning.
Duh, that just sounds like trains would be operating blindly in space currently and need to assess their approximate position.
> Perhaps I am read as suggesting that the problem is easy, and that is not my intention.
No, the issue is that you are suggesting far more complicated solutions to already solved problems, with simpler systems in operation for decades. The current system is that nobody in the train even has a say on where the train goes, so the problem you are trying to prevent doesn't even exist. This IS why it's way more safer than a car. There are movement authorities, that define from where you are allowed (and have to) drive with your train. The problem is not, that the train driver isn't able to know where he is and hence drives wrong or too far (that would be prevented by the on-board safety system), but that the movement authority itself is faulty.
On an up-to-date signaling box (withing the past 6 decades), even the train dispatcher is no say in safety questions. You could put a monkey in charge of it. There would be chaos, but they would not cause a crash. The current job of a dispatcher in normal operation is to assign resources to prevent deadlocks and to implement vaguely defined priorities. (Basically the equivalent of the public thinking a programmer is a code monkey, while the actual point is clarifying stakeholder interests.)
The actual issue here is, that while these safety system have a very small false positive rate, they do have a too large false negative rate for there to be an acceptable availability. Hence in the latter case, the human needs to take over and then you are back to a much higher false positive rate. The issue would be alleviated by relaxing the constraints on cost per availability. Either by allowing for less availability or by reintroducing more humans, so that the system situation can be assessed by humans directly.
These accidents are caused as follows: the automatic system fails, because the internal state of the system does not match the actual state of the world. Hence the human needs to take over. But the human also needs to rely on some system to know the world state. Which systems can he trust, given that the whole situation is that the systems report that he can't trust them? So he needs to make some decision and in most cases, that decision is still correct. But there is still an error rate to that, and then something like what we are discussing happens.
> But for cars this was solved decades ago for routing and years ago for self-driving.
This is absolutely not solved for the cars, and to the sense that it is, it was solved and rolled out from the 1870s onward for railways using mechanical computing systems, the switch to using electricity happened in the 1910s.
> Flying is organised with a very clear 6 sigma approach.
You are correct, that aircraft safety systems need to be designed to a higher reliability than railways, because on a rail you can always stop in case of an error, while in the air such a choice doesn't lead to a safe state. But if you compare these safety systems, basically aircraft is operated like railways used to be operated in the 1920s. (My peers actually had a task to compare them and find ideas from one that can be applied to the other. While there is a lot of automation to be taken from rail that can be applied to the aerial industry, there is not really much that can be applied the other way.) It is also operated with the amount of personal than 1920s railways. That's because there is a lot of money in aircraft, while railways are mass-transit and need to be cheap. If you would operate today's railway with the amount of human oversight than in the past, it would be a lot safer than aircraft.
> there is clearly something lacking for trains, when compared to other types of transport.
What are you talking about? Railways are so much safer than cars. https://news.ycombinator.com/item?id=50288518 Yes, there are less accidents in planes than in trains, but this is due to what I already explained.
That's a research topic, because the infrastructure companies would like to not pay as much for maintenance and still have a high sequence of trains. Also with track based train control systems you can only have very high resolution in specific places, where you place your track-side infrastructure, but it would be nice to have that resolution anywhere you like.
Also the fallback procedure is also aided by automatic systems and a sizable number of accidents in the past were caused by that information being faulty.
There will be a so-called "train order" allowing passage of a specific section ignoring the safety system warnings, which has strict validity limits both in time and in the area where it applies, usually denoted by specific hectometric mileposts
When cab signaling is involved (LZB is one of these) and it malfunctions, the entire system normally changes to "driving on sight only" - which indeed limits the train to 40, 30, 20, sometimes - 15 km/h (see https://fr.wikipedia.org/wiki/Marche_%C3%A0_vue) or the line gets switched to lineside signaling - if it is available.
I don't know how you could violate all of those rules - both from the driver's side and from the traffic control side - but it sounds absolutely horrible. Like an override of at least 2 (if not 3) very explicit safety margins.
They were the wrong orders apparently.
I remember a long time ago I was stuck in a train in a field a considerable time because of a similar failure and conductor just wouldn't move unless green
I was expecting the same here, conductor is the first to die so just refuse until the idiots fix their system
What exactly?
A conductor always just gets a movement order. They are not able to assess whether the track is clear, that's the reason why the signalling system exists in the first place. How they get that movement order doesn't necessarily tell what the security steps were to back it.
Of course an attentive conductor can notice and mention there something being weird ("Doesn't the other train normally arrive first?"), but that's a rare lucky occasion, nothing to be relied on. And they just need to swallow the answer ("No, you go first today...") anyway.
> and conductor just wouldn't move unless green
The conductor won't ever move unless they get a movement authority, which most of the time is a green signal.
Being a snowflake here has 2 benefits:
1. Getting company managing tracks to fix the lights (they need to deal with angry customers and pay off damages for delays and more), so there's a direct path from unreliable lights to economic damage.
2. Avoid crashing and killing yourself and passengers on the offchance the person on the radio is a moron
Yes, but not because of the light itself, but due to the safety steps done before. Which should also have happened before the movement order in any other form.
As a train driver, you do not have the information required to distinguish these situations. If drivers simple refuse all movement orders, besides "green lights", running trains will become a rare occasion and the drivers will simply get fired for not doing their job. _The train driver is not the one who decides where a train goes._ For this safety-relevant decision a driver is (roughly speaking) nothing more than an innocent bystander.
You can think of a train driver more of the person who makes sure the automatic engine works correctly and also has an eye, that nothing weird happens. Most of your train driver education is knowing how the train works and how to get a broken train back working fast. In addition you also learn the safety protocols how you get the information in which state the engine should operate in. This is what train signals are, it's not really the equivalent of a green traffic light for car traffic.
It cannot be bypassed, if an operator must go through a red they have to manually reset the e-brake on each car once it passes the signal.
Dyatlovs seem to be born everywhere.
Your suggestion about limiting speed after a shut down is a good one. On top of that, the rail operators should have spotted a trend of repeated safety system overrides and investigated why that was happening.
That’s why people here, when they hear the fire alarm they just wait for it to go off: the probability that it is actually a fire is minuscule… but the alarm triggers a lot.
Not sure how to actually solve this… but I’m also not making excuses for what happened. High speed trains is not the same as a fire alarm in some office building, the people in charge should be held responsible somehow.
Because of this, I discovered that (apparently) NY Fire Department charges $5000 per false call on an alarm system directly connected to the dispatch system.
Somethng to think about.
Honestly it's remarkable to me to think that anyone ever gets to that $500 "excessive" tier, I've had one false alarm where the fire department attended in years of having an alarm system and I was mortified. felt like the biggest idiot in the world.
https://www.nfpa.org/news-blogs-and-articles/blogs/2023/03/0...
I wouldn't think code dictated the alarm type. (I just replaced all nine sensors in my home due to age and went with all photoelectric this time and it was less than six months before I had my first false alarm. Never had any false alarms with previous ionizing type.)
We once got an alarm because the heating element in a computer room air conditioner had turned on for the first time ever. It was defective and started to smoke. Smoke detection tripped, buzzers sounded, lights on a panel showed where the problem was, and alarms went off in the security control center. But this didn't trigger building evacuation or full power down. That took confirmation from a second sensor.
Someone ran into that computer room, saw smoke coming from the A/C unit, and pulled the big red power switch, installed by the safety people, on the air conditioner. Then we had time to shut down normally, the safety people came to clear the alarm, and the HVAC people came to fix the problem. I kept the burnt heating element on my desk for a few days for people to see.
This is typical for big industrial plants. Bad stuff will happen, and you have procedures for it.
You never want to supply any reason for someone to demur about reporting a fire.
> Healthcare: The constant sounds of alarms and noises from blood pressure machines, ventilators and heart monitors
> Amber Alerts: sent to cell phones as far away as [...] 15 hour drive
> "known to the state of California to cause cancer"
etc
https://www.youtube.com/user/USCSB
See also a million USCSB industrial disaster postmortems
Should probably be: "known to the state of California to be a class N carcinogen"
I prefer to risk my life every day at not knowing what the government thinks is really important for me to know.
I was interested to find a discussion of the trolley problem in a book of out-of-copyright Norwegian-region folk tales (in English translation) that Amazon recommended.
Guess whats the consequence of that? Less and less people pay attention to the alerts.
Government officials are terrified of taking the blame for another Valencia style flooding catastrophe so any hint of rain blasts the mobile phone emergency system. Once the alert has been sent the officials can feel safe in the knowledge that they've done something.
https://en.wikipedia.org/wiki/2018_Rome_escalator_accident
fix the alarms? I only had one false fire alarm in my life. and thankfully zero real ones. it's possible.
do fire drills? if alarms get ignored, and you can't reduce the false-positive rate, then introduce fake alarms and monitor the response?
(...on track)
https://en.wikipedia.org/wiki/Alarm_fatigue
This literally happened to me last night, I was having dinner at my apartment, and suddenly I start hearing a smoke alarm, but not quite inside the apartment, I just kept having dinner thinking "bah, someone probably burned a toast".
Then it wont stop, I walk to door and hear people talking, still don't bother enough, wait a few minutes, then go out and my neighbor said "there are three fire trucks down there, I think it's a real one" hahhaha
The hallway was kind of hazy and smelled like burnt food, for sure... so I just grabbed my laptop and went out hahaa.
The building fire alarm is soooo loud and obnoxious, you _want_ to leave the building at speed. (Which I think is the right way to do it.)
Safety culture is blameless, but only if everyone plays along.
I know that this was likely a typo, but it is also a genuinely great word for the sort of attitude related to these situations.
What I'm saying is: false positives should not be ignorable, and modern systems take that choice away (at least, just before the situation becomes unavoidable in worst-case analyses).
That being said, previous fatal accidents in Spain's high-speed rail have resulted in "primitive" uncontrolled areas between controlled areas. Those SHOULD NOT exist. You are essentially saying "lives don't matter that much here " ($/life).
[0] I work in rail safety.
But train traffic systems seem to be a hodgepodge of different systems, perhaps locally grown and driven by the local vagaries of politics and rulemaking.
What a surprising inversion of expectations regarding safety.
What we know so far about Spain train crash - https://news.ycombinator.com/item?id=50286197 - Oct 2026 (84 comments)
Wait, I thought Spain's high-speed rail network was all ETCS L1 or even L2?
15 or 20 years ago when I took the train it worked well.
Now there are more trains and they increased the traffic like by 70% if I am not wrong and the budget for railway infrastructure by only 17% and it seems to not scale well enough, for whatever reason I do not know all the details.
There are a lot of railway tracks that are not in good state so speed must be lowered. There are incideents and delays routinely, all the time.
This did not happen until like 10 years ago and it has gotten worse and worse since then, not only in high speed trains.
The roads is a mess also: 52% of infrastructure for roads has bad or very bad defects in it.
The thing is that we have a record in government incomings and the services, ALL of them (healthcare, roads, infrastructure...) slowly collapsing.Part of the money is not going to the right places. I think that nearly 40% of the budget goes for retired people. We have 9.5 million pensionists in Spain.
We have to change that system and rationalize government spending and welfare or eventually everything will collapse.
Roughly 31% of Japan’s budget goes to social security. They don’t have problems keeping their high speed trains safe.
Cutting pensions won’t make trains safe.
I will also point out that on its own without further context, a high percentage of government spending going toward something doesn’t make that spending irresponsible or misappropriated. In the United States, a very high percentage of federal taxes are spent on Medicare and Social Security. But it should come as no sirprise that a very large percentage of federal income tax revenue is directly appropriated to pay for those things.
https://elequidistante.github.io/graficos-jongonzlz/pensione...
https://elequidistante.github.io/graficos-jongonzlz/pensione...
https://elequidistante.github.io/graficos-jongonzlz/pensione...
And maybe this is the most illustrative:
https://i.redd.it/uwvgxycxhjeg1.jpeg
So yes, the reason why we are underinvesting in pretty much everything is basically pensions. GDP is up, tax collection is up, debt to GDP is sligthly decreasing... but pension expenses keep growing at a fast pace so there's less and less money for everything else. And I say this with both of my parents earning the maximum pension, so I don't have an axe to grind, but it's just reality.
I am giving an objective explanation in all honesty: Spain needs a pensions reform probably at some point bc it is 40% of the expenses in the yearly budget, with a deficit and a demographic deficit. This will explode.
If it can be taken from elsewhere, better.
But you know how much are pensions in Spain and know our pension system in detail (it is literally a Poncy system...)? They are often higher than people working!
Whether we like it or not, we need to reform or collapse in the future. I wish it could be taken from elsewhere, but 40% is a lot...
There is a lot of useless expenses in public work in our "federal system" (comunidades autónomas).
Their trains are safe, but they also have 2X the national suicide rate as Spain, which amounts to about 17000 more deaths per year. I'd attribute a big chunk of that to their work culture treating people like machines, whereas Spain's work culture tends to lean towards treating people like humans.
That isn't an excuse for railway mishaps, of course, but I'm just trying to de-romanticize Japan as some kind of magical perfect place. It's not. They might have gotten their railways right, but they have massive safety issues around mental health.
You clearly have not worked for the average Spanish employer.
But under-maintenance causes trains to stand still and be late. It does not cause them to crash.
Crashes are caused by running at speeds higher than the (under-maintained) rail can support, or (against all rules and every regulation) no cap on speed when the signalling system is down.
The latter can not be solved with more money and resources. It is a culture problem. Rules can not routinely be disregarded for arbitrary reasons, especially not when they are completely in line with common sense.
Still I agree, pension systems in most EU countries are unsustainable.
Pensions is 13%PIB which is on the European median.
The problem is demographic. Also take into account that retired people have paid for their retirement.
Your rhetoric is not what I'd like to be promoted as the first answer entering. Just reading the title of the news I knew what kind of messages I'd see promoted.
No, they have not. It's a pyramid scheme. Whatever they put into the system when they worked probably doesn't even cover 5 years of retirement.
The LZB system, which broke down, had the data you describe. It knows when trains pass over fixed sensors so it computes where they are, and sends data packets to specific trains informing them their current speed limit, and the next, and how far away that is. If the driver won't slow down, the train will.
When LZB broke down, they had to switch to their other system, BSL (fixed block signalling: https://en.wikipedia.org/wiki/Automatic_block_signaling). You can then know the distance to the next block, and if it's occupied or not, but not where the train is inside the block. You can only guess.
In the next few days we'll likely find out if the control centre also fucked up the block signals...
That's where the EU came in and developed ETCS (https://en.wikipedia.org/wiki/European_Train_Control_System) as a modern alternative. Unfortunately, the EU doesn't have the legislative power to force member states to adopt it and also not the money to bribe them. So ETCS is still competing with the legacy systems.
However, the reason for that crash apparently was the dispatcher who greenlit the cab driver to go full speed ahead after the train control system on that track had crashed even though they knew that another train was reporting that it was unable to restart and get going. Procedures in case of a train control outage are clear: all trains can only move at a max speed of 40Km/h - slow enough to drive and brake on sight.
Instead, that train crashed into the stationary one coming from 200Km/h
I set my favorite agent on the task (Opus 5.5 in the Kagi Assistant), and given the two rail crashes in Spain this year, these are the stats it came up with for "chances of dying" via various modes of transportation between Seville and Madrid:
* EU high-speed rail, long-run average: ~1 in 36 million
* This rail line, counting both 2026 crashes: ~1 in 400,000 to 1.2 million (prior to the most recent crash it was 1–3 million; now ~2.5× higher)
* Flying with a European airline: ~1 in 80 million
* Driving: ~1 in 1 million or worse
Of course this is hindsight. Heightened awareness of risks, higher propensity to overreact to anomalies or alarms, procedural changes, and so forth in the wake of this second crash might push high-speed rail in Spain to be higher than the European average in the future.
Meanwhile no high speed rail between València and Barcelona, because that would somehow erode the power of the central elites.
I would actually sit in front now. Sometimes you would be able to still get vital information and being actually able to act. But the safe decision would be no to enter the train.
You might just as well never leave your bed, that's even safer ;) Train travel is much safer than travelling on roads, and in the same ballpark as commercial flight.
Optimistically assuming you have a minute to react (I'm imagining closer to 10s), what could one possibly do?
I don't see how this would fall on the drivers at all.
A person saying you have a green light when you have a red light is not the same information at all. The probability that something has gone wrong and will lead to disaster is many many times higher.
As we also know from the aviation industry, controllers are human and therefore will make mistakes. A controller shouldn't issue a wrong order, but a driver also shouldn't accept an order they aren't certain about, and there should be technical systems backing both sides of that up.
It doesn't "fall" on the driver, but it doesn't "fall" solely on the controller either. It's a systemic issue, and many pieces have to fail for a disaster to happen.
Also stopping distance for trains is huge. This video for high speed trains says 5km (3mi) https://www.facebook.com/Renfe/videos/%EF%B8%8Fcu%C3%A1l-es-... That is probably at full speed, but IIUC the accident was at half speed so the distance should be like 1.2km (0.8mi).
The aviation industry operates like the railway industry ~1920 (somewhat by necessity).
> You wouldn't drive your car into a lake just because your satnav tells you to, would you?
You are assuming a train driver is equivalent to a car driver. He's not, the analog would be more a repairmen that you always take with you on journeys.
Sadly we'll probably watch a lot of individuals being blamed/scapegoated for systemic issues, but hopefully even Spanish politics can organise a proper investigation after this many deaths in a single year.
A train driver has zero insight in what is going on and where other trains are. They do need to trust the orders they get, if you want to question every order you will never start to drive.
That's why it's a union job
Also he's the first person to die on accident so it's that and the safety of everyone else
They do not 'need' to follow others, they just need to refuse unless all safe and green.
If they never start to drive it's the companies problem to deal with angry non-dead customers
Every train network has situations where drivers are authorised to proceed against a red signal. Not usually at full speed though.
At most face unlikely discipline.
Here they would even have valid reason to refuse - order was given for full speed, regulation says low speed ready to stop.
So a "No, i'm not doing that, you're moron" would be justified.
There is no point in the train driver making a decision about where the train goes, because he has no information for that decision. Hence it is also not his job. Like, yeah if he has reasonable reasons to think there is something wrong, nobody is going to fire him, but what is the policy that allows him to do so, while not just randomly deciding to not drive today? There is no difference for him, until he is about to die.
Never would a pilot be reprimanded for refusing an ATC order to move their plane in a way that violates established protocols
Then what the fuck is this country even doing with trains.
No, no no, no no no.
Interlock safety systems exist for a reason. In any safety system where the interlock is down you do not resume standard operations. Ever. Why, because there is a book with blood that is 10,000 pages deep that describe the horrific accidents that happens when you do. Might as well be an axiom at this point.
>because somewhere on the track he doesn't see, the asphalt might be broken.
Again, stay away from analogies and safety critical systems.
The person behind the break and speed control of the train is no different from the captain of the airplane or the captain of a ship. They have full authority control to stop the train and refuse to move it until they are sure of the safety conditions. Any attempt to fire them should result in an immediate stop work from every employee in the system until they are put back on the job and the safety concerns are resolved.
That has nothing to do with a single country. Above 40km/h you are not allowed to drive on sight in a lot of countries. I don't know how it is in Spain, but in Germany, you are also not allowed to drive via track-side signals above 160km/h. You can simply not decide about where it is safe to go from inside the train.
> Interlock safety systems exist for a reason
Yes, and that's a job of the dispatcher, not of the driver.
> In any safety system where the interlock is down you do not resume standard operations.
That might be nice in theory, but that has not much to do with reality. There is simply always something broken. It doesn't even need to be a signal, way more often a crossing doesn't properly report that it is closed.
> The person behind the break and speed control of the train is no different from the captain of the airplane or the captain of a ship.
Nah, it's very different. For one a captain or pilot can control the direction of the ship/plane. They can also determine whether their operation range is clear. A train driver can do none of these things. What's the point of making them responsible for safety if they neither have the knowledge, nor the lever to change things? Trains are more secure, because the driver is not responsible for the infrastructural safety, not less. That includes whether the track is clear or not.
The point of this discussion is that people blame the train driver or say "use self-driving", when that is not going to solve the problem, because that's not where the error is. The error is not there, *because* for rail making errors operating the train is not going to cause an accident (most of the time), which is not the case for cars.
I agree. But the decision whether all switches are locked in the correct position and that the track is clear, is not one that he is supposed to make and he also doesn't have the information for it.
> The controller and the driver both went with full speed despite it being completely against regulation on a red signal.
Going full-speed in the case of a red signal is not necessarily against regulation. Also the information of "red signal" or "you can go" is both a signal from the same source. There is no information for the driver to make a different decision over the dispatcher.
I can't comment about whether the current accident was caused by going against regulation, and more important by whom and against which. We need to wait for the proper safety report, not for a BBC article. If you take the latter at face value, it would mean there are clowns operating, which I am sure, is not actually the case. The real error is always way more subtle, otherwise it would not have happened.
A written movement authority is a signal as well in railway terms. It's more like "I don't trust your second traffic light, that you placed next to the normal one, because the normal one is broken".
Potentially, but the point is that signallers should physically be unable to allow trains to proceed, and drivers should physically not be able to override them. British signalling from the 1800s has physical interlocks; this isn't a matter of manual versus automatic train operation. It is clearly systemic.
The reason vehicles are still driven manually is because humans rely on transportation every day, all of the time.
If signaling worked properly then it wouldn't matter whether the train was driven autonomously or not, the "problem" becomes trivial. Establishing and continuously verifying that signaling is working properly is the hard part.
Without signaling you're limited to crawling speed just like humans are when they don't have any signalling .
The current system is basically that the train is driven both automatically and by a professional attentive driver at the same time. Changing it to just the automatic system is going to reduce safety. Also the real world is way to messy to reach acceptable availability rates with only automatic systems.
[1] https://www.itf-oecd.org/sites/default/files/spain-road-safe...
In this case the “object” was another train. That’s not the “hard” part of the problem. This sounds like an apologist comment.
Are there systems that can warn drivers and prevent collisions without external signaling, like ACAS?
Detecting an object on the tracks 2 km away (say), as opposed to beside the track at the same distance, is in fact a hard problem. The tech used in self-driving cars is not going to solve it.
Spain train crash
https://news.ycombinator.com/item?id=50271032
Salary for ministers is around 80k euro per year. Yes significantly more than the minimum salary but hardly a fortune.
I could not believe it, but it is actually true:
The average gross annual salary in Spain is €29,540, which translates to approximately €2,461 per month before taxes.
It sucks but that's how it is over here. It's "my" party the one in power when a catastrophe like this happens? It's not the politicians, it's someone else. Is it the "other" party? Surely the politicians are ultimately responsible.
This reflects on the news media as well.
- Not Spain. This was Bedford (UK) in June 2026.
https://en.wikipedia.org/wiki/2026_Bedford_train_collision
The train collided rear-end into the rear carriages of the other train and derailed, which also resulted in the three rear carriages of the first train to derail
- This was Białośliwie train collision (Poland) in June 2026
https://en.wikipedia.org/wiki/2026_Bia%C5%82o%C5%9Bliwie_tra...
One carriage was reported to have overturned and four more were derailed. 44 of the passengers were injured
- And this was the Cleon Derailement (France) by sabotage in September 2026
https://en.wikipedia.org/wiki/Cl%C3%A9on_derailment
In this last case Police suspected sabotage after a 300 Kg piece of rail was found deliberately laid in the railway.
"A fire was detected in the rear cabin of the high-speed train. Following safety protocols, the 283 passengers on board have been evacuated"
This was an AVE passenger train in the line Madrid-Barcelona, in October 2026. Most probably another case of sabotage.
"Add a global memory. Whenever I'm in Spain or planning to go there, remind me of this: <story url>, and plan to avoid it."
- trains go in tunnels or tracks are between houses. When train control systems were defined in the 1990's, there was no way to make them sensitive enough to record GPS positions. Instead there is a different location system based on so-called balises with a fixed position on the tracks. Every time a train crosses one, it knows where it is.
- Planes go in 3 dimensions, trains in one. If ATC wants to ensure two planes do not collide, they will assign them different headings and/or heights. Precise position isn't that important. Trains cannot avoid each other, that's why they move in blocks.
And yes, they do signal their position back to the control center, it's just a different protocol