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.
Mostly because metal wheels to metal rails contact offer very poor friction
This happens with aircraft tires and those get used for a very short duration at high speeds
I think this has been misreported and it's even worse, EU register of infrastructure says that maximum permitted speed for this section is 270km/h and the sections before it are even higher.
https://rinf.data.era.europa.eu/unified-search?view=map&q=JT...
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.
"I will not accept that it's a highly dangerous road" -- https://www.youtube.com/watch?v=7Qir4EEpawE
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.
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.
https://komonews.com/news/local/13-year-old-boy-killed-while...
Here in Australia, a member of my family was involved in a fatal accident with a pedestrian, around 20 years ago. They put him on trial even though the case was weak, and then the prosecutor moved for dismissal part way through the trial. But, what people told us, is prosecutors are encouraged to take weak cases to trial because dropping the case part way through the trial is more politically palatable than refusing to bring it to court to begin with.
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.
Cars otoh don't have someone overseeing everything and directing traffic. They have to operate by sight.
What does normal mean ? Maybe part of the reasoning is the driver thought normal means 200km and the dispatcher meant drive y sight, which from what i can tell should be the "Normal" action taken when the LBZ system is down.
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.
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.
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.
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.
[1] https://www.dlr.de/en/kn/research-transfer/projects/next-generation-train/rcas-railway-collision-avoidance-systemBecause 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.
>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.
X on its own would have solved this particular crash, yes.
X + existing setup would solve this crash + all the other crashed the existing setup solves.
Forests are irrelevant; rail right-of-way contains no trees, and is wide enough to assure clear "view" of satellites.
Absolute nonsense. Do you have any idea how long some tunnels are?
But yes there does not need to be a limitation on there only being a single train in a tunnel.
"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.
Oh, they can, but it's usually a very traumatic event.
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.
It's not impossible. But handwaving GPS placement of trains at the correct location, direction, and track deserves more than a handwave as trivial.
Presumably switches already report their position to somewhere.
It's absolutely unacceptable for this problem exist in today's world.
Yeah and this somewhere already knows whether a crash is going to happen. In which case your solution brings no benefit. You can't rely on the correctness of a system, which you want to make an alternative to, to help in the case the original system fails.
This discussion focuses on a non-problem (granted partly due to an imprecise comment of mine). The system knows where all the trains are and also that a crash will happen, if the decision is made, that then indeed was made.
What is needed is that the system needs to convince the operator there is still a problem, after it proved itself unreliable. My suggestion would be a log of the constraints the prover encountered while determining whether there is a conflict. This certainly already exists somewhere in the background, but I am not aware whether that is currently shown to operators in deployed systems. It does exist somewhat in the research systems we use in university.
The thing is that in modern automated dispatching you only have the same world model as the automatic system, so when there is an error you have the same world model as the system, but that just detected, that that does not equal the actual state of the world. And often the error is in fact a false positive.
But now, I actually think that this accident was caused by several systems being in effect: https://news.ycombinator.com/item?id=50298796
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.
On the other hand this is a complete non-issue and solved for more than a century on the network level. So there is zero need to invent satellite or vision based train detection at worst even using statistical systems, when you can use deterministic systems, for example using the fact that a train is out of metal, so it's detectable by the train closing a electric circuit between the rails. Or using the sensors that are installed at every signal, switch or other positions for precisely this question.
As a passenger, I'm very glad software engineers haven't (fully) taken over aviation and railway safety yet.
I cant recall but maybe a year or two back in ES, a train on one line was derailed around a curve or something and a train at high speed in the opposite direction hit the derailed train.
It seems like a very bad design to have rails that close to each other when for minimum cost they could have significant separation especially when the rails are over open flat ground. Bridges and tunnels of course might be exceptions to this, but over open ground the cost should be low enough that there could and should be separation.
Aviation also doesn't exclusively rely on GNSS positioning, so why should train protection, given that it's also extremely safety critical?
My car's GPS does, using dead reckoning.
Trains can also use dead reckoning.
/me checks notes, I've heard that they move on inflexible things called "rails" that almost never change the location.
Also the hard part is knowing the position of the others and their trajectory, which changes in between moving towards them and is done by a third party. The normal passing distance is smaller than the width of your vehicle and you can only change your own direction every few kilometers. That means that the others trajectory towards you can only become known after you are already past your last opportunity to change your trajectory and even within your breaking distance. Good luck!
[1] Friction for cars on the road is 0.010-0.015, for trains 0.001-0.002; train speed 120 km/h * 7.5 = 900 km/h equivalent for car; that's not even a high-speed train.
You also can get periodic absolute fixes to correct for the accumulated drift.
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.
> 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.
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.
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.
GPS can't work for trains, they go inside tunnels and between walls. Track circuits and train sized NFC-like tags reporting linear locations, mentioned as not scaling in GP, is the standard solution. It kinda scales fine.
1: https://futurism.com/advanced-transport/waymo-crashed-into-e...
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.
I think you are misunderstanding the sentence you quoted.
It says something about the safety of self-driving cars. That is they don’t meet the standards required for railways. In other words the expected safety for a self-driving CAR is lower than the expected safety of a RAILWAY. (Caps for emphasis, sorry about the shouting.)
Your comment reads as if the quote claims that we cannot make “self-driving trains”. It does not say that.
> You keep pretending that avoiding train collisions is too magical to achieve with current tech
I don’t think that they do that. Definietly not in the comment you responded to.
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
Japan railway crew have stricter procedures when they are alone: https://en.wikipedia.org/wiki/Pointing_and_calling
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
This you? Who's fault is it then? You said the tech doesn't exist (lets take that at face-value for the sake of your argument), so then if not tech, then what? You're just left with people. So are you saying it is their fault or not? Or is it just nobody's?
In addition: https://news.ycombinator.com/item?id=50297950 https://news.ycombinator.com/item?id=50293093
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.
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.
[1] https://www.dlr.de/en/kn/research-transfer/projects/next-generation-train/rcas-railway-collision-avoidance-systemThat'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.
I guess a much less dense and largely overground network, mainly used by fairly slow moving freight trains as opposed to highspeed passenger connections, changes requirements somewhat.
I mean they are systems that rely on GNSS in Europe, but no safety systems, that would be simply to unreliable. For example I believe the railway announcements in Germany to depend on GNSS. They are also unreliable.
There are also other solutions, e.g. LZB uses a phase change of the signal every 100 meters as an additional precision signal.
Isn't the ability to do so the basis of operation for e.g. the German LZB train protection system, which has been around since the 1960s?
If you mean that train protection systems don't (exclusively) rely on self-reported positions, your statement makes a bit more sense, but even that is changing with e.g. newer ETCS levels which do rely on self-positioning more and more.
I did not say "train systems are ...", I said "trains are ...". This is referring to e.g. that odometry based on wheels results in a drift. GNSS is to imprecise and unreliable. I'm aware that you simply use balises, that's what I meant with "markers in the track". However that's based on the infrastructure again, so it's again not trains on their own.
https://news.ycombinator.com/item?id=50293093
It was simply supposed to be an example how GPS sounds like it should easily solve a problem, but does not without additional measures, that then do not need GPS anymore.
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.
> Some reports said that the renfe train rolled for 25km - if this is what their fallback is like - it is absolutely inexcusable. Oh my...
I do not know what you mean with that, and what "rolling" would mean here.
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.
In some industries that is how they keep costs low while pretending they are being safe. They have alarms or procedures that say something is bad or wrong, but fixing some problems costs more money than it saves so they want them to be ignored, and managers will get angry and admonish you or eventually fire you if you keep following procedure and stopping to check problems. So eventually they build a team of people essentially trained to ignore problems. Which is why many oil pipelines still use ancient and unreliable leak detectors, they know those systems are unreliable and the operators will get alarm fatigue from the 200 false alarms, and that way they also ignore when a real problem happens, and worse case for the company they scapegoat the operator. They don't care that 2,000 gallons of oil leaked into the wilderness and poisoned the land if it would cost 2,000+ gallons of oil profit to shut down and repair the leak. They have a financial interest to not fix it.
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.
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.
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.
Normalization of deviance,
https://hn.algolia.com/?query=normalization%20deviance&type=...
Humans never learn.
Also lots of potentially angry passengers who want to get to their destination in time. Will miss important appointments, or even the last train connection for the day and be stranded if the train drivers decide to wait a little bit longer to be on the save side.
(have you ever been in a train on hold, unclear information about delay and seen the looks and talks of passengers towards the train driver walking outside who announced before he also does not know when the ride can go on? Like he is personally responsible for the delay and incompetent or straight evil)
Also in this case - why the hell they just did not wait for the primary safety system to go back online before doing anything ? Is it so faulty that they get used to it being broken or what ?
And baring that, how is the train even able to go full speed without the primary safety system being operational ? It really should be hardwired to cap the speed at 40 km/h or even less (including zero) unless the safety system is confirmed online and operational.
IIRC the japanese Shinkansen trains use a system called ATC (https://en.wikipedia.org/wiki/Automatic_train_control#Japan) since 1964 (!) which automatically starts breaking if a train goes faster than the maximum allowed speed in a track circuit. So presumably if connecting with the track circuit is lost the maximum speed defaults to 0 & all trains stop until proper protection is restored.
There are not that many people who (care to) see the big picture(s) and the consequences their semi-small actions may have in the long run.
> -Charlie Munger
Dyatlovs seem to be born everywhere.
Seems unnecessarily unsafe when your attention is on driving anyway, the only difference being you arent "offocially" driving.