Serious Accident in Bavaria

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Llanigraham

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Another possible similarity is shift changeover time.
The accident occurred at 06.45 just when you would imagine the shift changing and 2 people in the box. This is well documented as a dangerous time in many occupations not just railways.
Which is why, in my Box, if there was a train in section we would only do the handover after it had cleared the Section signal.


In the harsh light of investigation it seems incredulous that a professional, well trained, qualified person in a safety critical role can simply "forget" something, especially something as big as a train. However, there have been many accidents caused by this very thing, the signalman convincing himself that the situation is not as it really is, thankfully getting fewer and fewer as technology is introduced to mitigate human failings.
Cough. Moreton on Lugg!
 
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AlexNL

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I have attempted to create a schematic drawing of the track layout between Bad Aibling and Kolbermoor:



I have based my drawing on these cab-ride videos:
- Bad Aibling to Kolbermoor (29:00 to 36:30)
- Kolbermoor to Bad Aibling (03:00 to 10:30)

Please note that there are a few foot crossings which I have not drawn on this map as they are not protected by a signal. Also, the drawing is not to scale.

About the infrastructure:
- Axle counters are used for train detection.
- All main signals on this track have a Zs1 alongsides them.
- The signals at 28.7 and 29.4 are automatic block signals, and are connected to the level crossing at 28.8.
- In Germany, main signals are usually placed a bit before the start of a block or danger point, this allows trains to come to a full stop before reaching the point of danger.
- I suspect the block division to be located somewhere between 28.8 and 29.2.

This is what we know so far:
- The timetable of both trains:
Code:
+--------------+-----------+-----------+
| Train nr.    |    79505  |    79506  |
| Direction    | -> Kmoor  | <- B. A.  |
+--------------+-----------+-----------+
| Bad Aibling  |    06:38  |    06:51  |
| B.A. Kurpark |    06:40  |    06:48  |
| Kolbermoor   |    06:44  |    06:45  |
+--------------+-----------+-----------+
- The trains are scheduled to meet each other at Kolbermoor. The westbound train has a 5 minute stop there to allow the eastbound train to pass.
- The eastbound train was delayed by approximately 4 minutes, the westbound train was running according to schedule.
- The eastbound train was supposed to remain at Bad Aibling, to prevent the westbound train from getting delayed as well.
- At Bad Aibling, both trains use platform 1 at this time of day.

Here is what I think what has happened:
- At 6:43, the eastbound train left Bad Aibling, after being given a Zs1. As both trains were planned to use platform 1, this could explain why the driver did not notice anything unusual as the points in front of him would have already been pointing in the right direction.
- After a short stop at B.A. Kurpark, the eastbound train resumed its journey at 6:45.
- At 6:45, the westbound train left Kolbermoor according to schedule.
- When both trains initiated their departure, the block inbetween them was empty. The westbound train got a proceed aspect according to the timetable, the eastbound train got a proceed aspect because the next block was still empty.
- Both trains went past the main signals before the opposite train had entered the block beyond it.
- After leaving B.A. Kurpark, there were no more signals to alert the driver of the eastbound train of any oncoming trains.
- The driver of the westbound train could have been warned by the distant signal at 30.5, but as the associated main signal guards a level crossing it would not be unusual for this distant signal to show a 'caution' aspect.
- At 30.3km both trains collided head-on, without having seen eachother due to the curvy nature of the track.

* Source: Tagesspiegel
 
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AlexNL

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An important difference is that PZB can't enforce speed limits at all, all it can do is start the braking curve (165 -> 85 -> 65, 65 -> 45, 0). At a green signal, PZB will allow you to go 165 km/h irregardless of the actual line speed.
 

Taunton

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Cough. Moreton on Lugg!
If we want comparisons to comparable UK incidents, I would say Norwich, in 1874, and Foxcote, on the S&D, in 1876. Those were 140 years ago, and controls thereafter prevented trains being able to be given a clear signal from both ends of a single line simultaneously due to errors by the signal staff. Who would have thought that 140 years later Germany has not managed to catch up.
 

BRX

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- When both trains initiated their departure, the block inbetween them was empty. The westbound train got a proceed aspect according to the timetable, the eastbound train got a proceed aspect because the next block was still empty.
I don't understand how this can be possible. Surely any signalling system can never allow signals at both ends of a block to be at green. Or do you mean that one of them was given a proceed aspect by one of te zs1/zs7 signals?
--- old post above --- --- new post below ---
I noticed looking at the cab ride video that there's quite a distance between the end of the platform at Kolbermoor, and the signal protecting the entry to the single section. Could it be that the driver had a green light on departure from the platform, started off and somehow did not notice that it changed to red just before he passed the signal itself? But then surely the automatic system should have brought it to a halt.
 

AlexNL

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At that point the section would have been clear to Moomerland, so why would he have been given a Zs1?
My guess: a route was already programmed from Kolbermoor to Bad Aibling, so the interlocking rightfully prohibited the signaller from setting a route in the opposite direction. The signaller misinterpreted this as a signal failure, and gave a Zs1 to allow the train to depart anyway.

I keep reading of a 40kmh restriction when Zs1 Signal is in place, yet both trains colliding with about 100 kmh. Both driver and signalmans error?
I have read some mixed statements about Zs1, it is either:
1) 40 km/h through points, then linespeed
2) 40 km/h until the next clear signal

Either way, if you look at my schematic in post #152, you will see that there is another main signal at 28.7km. This main signal, as well as the opposite signal at 29.4, are automatic block signals.

As far as my understanding goes, these signals just check whether or not the block behind it is free. So, if the eastbound train had left Bad Aibling when the westbound train had not yet entered the block, the main signal at B.A. Kurpark would have shown a proceed aspect.

I've been looking very closely at the videos which I linked to earlier, in an attempt to spot the axle counters between the three stations. So far, I think I have spotted them at the following locations:

1) Around 28.2, besides the "Halt für Rangierfahrten" sign for Bad Aibling
2) At 29.1, besides the level crossing
3) At 32.2, for the "Halt für Rangierfahrten" sign for Kolbermoor

And then there are some small yellow boxes besides main signals of which I am not sure what they are. Anyone got an idea? I suspect some of them to be axle counters as well, but not all of them.

This is what makes me suspect that when the eastbound train was about to leave Kurpark, the westbound train had not yet passed the axle counters at 32.2. The automated block signal at 28.7 showed a proceed aspect as the block between 29.1 and 32.2 was clear, so the driver left the station. Shortly afterwards, the westbound train entered the same block.
 
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LAX54

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I have attempted to create a schematic drawing of the track layout between Bad Aibling and Kolbermoor:



I have based my drawing on these cab-ride videos:
- Bad Aibling to Kolbermoor (29:00 to 36:30)
- Kolbermoor to Bad Aibling (03:00 to 10:30)

Please note that there are a few foot crossings which I have not drawn on this map as they are not protected by a signal. Also, the drawing is not to scale.

About the infrastructure:
- Axle counters are used for train detection.
- All main signals on this track have a Zs1 alongsides them.
- The signals at 28.7 and 29.4 are automatic block signals, and are connected to the level crossing at 28.8.
- In Germany, main signals are usually placed a bit before the start of a block or danger point, this allows trains to come to a full stop before reaching the point of danger.
- I suspect the block division to be located somewhere between 28.8 and 29.2.

This is what we know so far:
- The timetable of both trains:
Code:
+--------------+-----------+-----------+
| Train nr.    |    79505  |    79506  |
| Direction    | -> Kmoor  | <- B. A.  |
+--------------+-----------+-----------+
| Bad Aibling  |    06:38  |    06:51  |
| B.A. Kurpark |    06:40  |    06:48  |
| Kolbermoor   |    06:44  |    06:45  |
+--------------+-----------+-----------+
- The trains are scheduled to meet each other at Kolbermoor. The westbound train has a 5 minute stop there to allow the eastbound train to pass.
- The eastbound train was delayed by approximately 4 minutes, the westbound train was running according to schedule.
- The eastbound train was supposed to remain at Bad Aibling, to prevent the westbound train from getting delayed as well.
- At Bad Aibling, both trains use platform 1 at this time of day.

Here is what I think what has happened:
- At 6:43, the eastbound train left Bad Aibling, after being given a Zs1. As both trains were planned to use platform 1, this could explain why the driver did not notice anything unusual as the points in front of him would have already been pointing in the right direction.
- After a short stop at B.A. Kurpark, the eastbound train resumed its journey at 6:45.
- At 6:45, the westbound train left Kolbermoor according to schedule.
- When both trains initiated their departure, the block inbetween them was empty. The westbound train got a proceed aspect according to the timetable, the eastbound train got a proceed aspect because the next block was still empty.
- Both trains went past the main signals before the opposite train had entered the block beyond it.
- After leaving B.A. Kurpark, there were no more signals to alert the driver of the eastbound train of any oncoming trains.
- The driver of the westbound train could have been warned by the distant signal at 30.5, but as the associated main signal guards a level crossing it would not be unusual for this distant signal to show a 'caution' aspect.
- At 30.3km both trains collided head-on, without having seen eachother due to the curvy nature of the track.

* Source: Tagesspiegel


IF, I have read your description right, then it was always a disaster waiting to happen !
 

w0033944

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If we want comparisons to comparable UK incidents, I would say Norwich, in 1874, and Foxcote, on the S&D, in 1876. Those were 140 years ago, and controls thereafter prevented trains being able to be given a clear signal from both ends of a single line simultaneously due to errors by the signal staff. Who would have thought that 140 years later Germany has not managed to catch up.
Those accidents came immediately to my mind as well.
 

EAD

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Hello again all - afraid work has kept me busy.

I think there is a lot of good conversation in here but also some misunderstandings. I have to say I can understand where people are coming from re British signalling practice, but the German system is not inherently unsafe. The issue is that the way the signaller has to ensure he can use a Zs signal is very prescriptive and the Germanic approach is that if done correctly you a) will see quickly why the interlocking won't let you override it and b) if there is a fault that needs an override you will have gone step by step through to identify it and made sure things are safe.

The state prosecutor is investigating and yes that centres on the signaller. As has been said he is in a very fragile state as one can imagine given what happened. The press conference was short (30 mins) and said very little other than to confirm that the signalling was operating correctly and the trains were driven according to the book. When asked it was confirmed the train from Holzkirchen towards Rosenheim was given a Zs1. This therefore means the train in the other direction was driving under normal signals and hence why the signal at Bad Aibling would not clear.

The signaller should have spotted this very quickly - even if on two panels, both were controlled by him in the same location (Bad Aibling). Even if he went through the rules to see if he could have given Zs1 then he would have seen the block was occupied. We now have to wait for the railway investigation to ascertain what exactly he did, because sadly it won't have been one simple step.

Then comes the question for the future as to how you remedy this - I think some of the comments on historic UK accidents are perhaps a little unfair as a comparison given this is a fully axel counter fitted and relay signal box controlled area. The question really is how can the German system where you the signalman are responsible for carefully ensuring there is a reason you can give Zs1 and the route is locked and free be improved on a single track line - I think we can all agree that is what must come out and no doubt will come out.

Zs1 is indeed 40Km/h in the station area so if on an exit (Asufahrsignal) at a station it is 40Km/h until clear of the last point, then you can accelerate. One thing that is still not confirmed is that the train leaving Bad Aibling to get where it did would have had to be given a Zs1 twice - once at the station Ausfahrsignal and one at the block signal, where shortly after the crash occurred. That is a puzzle as the signaller would have to have twice got it horribly wrong under the rules.

There is some debate in German railway forums over the nature of the block signal, but I don't think it is auto block given it is on a single line. On speed, the train heading towards Bad Aibling from Kolbermoor had been signal checked and was according to data released/leaked at 55Km/h at the time of impact, consistent with the block signal having fallen to red as the other train entered the block and the distant INDUSI magnet therefore being live and triggering the braking curve for a red signal.

In terms of emergency transmission - the signaller did twice send out one but was just too later (I understand there is indeed an equivalent of the red button on GSM-R there).

All in all terribly sad. Can things be improved on single lines - yes. But note there is also the aspect of mind set here in putting things on the signaller to prove the route is secured where there is a fault (track circuit etc).
 
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Taunton

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I think some of the comments on historic UK accidents are perhaps a little unfair as a comparison given this is a fully axel counter fitted and relay signal box controlled area. The question really is how can the German system where you the signalman are responsible for carefully ensuring there is a reason you can give Zs1 and the route is locked and free be improved on a single track line
I think the UK comparisons are quite reasonable.

The difference is that the German approach regards the signal staff as infallible provided they follow the rules. The British approach has long regarded the staff as the opposite, bound to make mistakes, and therefore needing protected from this by mechanical devices such as tokens, interlocking, and so on. Perhaps a copy of "Red for Danger" should be put in the post to the German investigators. As I've said before, this is not the first time, in my own recollection, there has been a head-on in Germany, with signals cleared from both directions, due to basic mishandling of things at the signal controls.

One thing that also strikes one is the sheer complexity and quantity (and cost) of signal equipment on what is a secondary single line, yet which still doesn't give the protection you get on something like Salisbury to Exeter. When you look at the videos the line looks somewhat like a tramway. It doesn't even seem to be fenced through built up areas.
 

NicholasNCE

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It doesn't even seem to be fenced through built up areas.
Nothing wrong with the lack of fencing, few if any countries share NR's obsession with fencing every single bit of their network. And this certainly had no influence on the events, if anything it probably made access by emergency services easier.
 

AlexNL

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One thing that is still not confirmed is that the train leaving Bad Aibling to get where it did would have had to be given a Zs1 twice - once at the station Ausfahrsignal and one at the block signal, where shortly after the crash occurred. That is a puzzle as the signaller would have to have twice got it horribly wrong under the rules.

There is some debate in German railway forums over the nature of the block signal, but I don't think it is auto block given it is on a single line.
The track layout schematic on the German Wikipedia mentions that the signals at Kurpark are of type "Sbk" (Selbsttätiges Blocksignal): automatic block signal.

I can't really see a reason for that particular signal not being an automatic block signal either. The single track piece is just 5 km long, the stations at both ends are controlled by the same Stellwerk and apart from the level crossing there is nothing spectacular (such as a connection to a factory) going on between the two stations.

If the level crossing hadn't been there, I would not be surprised if the line had been a long single block.

On speed, the train heading towards Bad Aibling from Kolbermoor had been signal checked and was according to data released/leaked at 55Km/h at the time of impact, consistent with the block signal having fallen to red as the other train entered the block and the distant INDUSI magnet therefore being live and triggering the braking curve for a red signal.
I don't think that is correct if you look at the schematic which I posted earlier:

(click to enlarge)

The last signal which the train from Kolbermoor has passed is the main signal at 32.6, just 300 metres away from the platform in a 30 km/h zone. Even if the signal went to red just before the westbound train passed over it, the PZB would have brought it to a complete stop well before the crash site at 30.3.
 

w0033944

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I think the UK comparisons are quite reasonable.

The difference is that the German approach regards the signal staff as infallible provided they follow the rules. The British approach has long regarded the staff as the opposite, bound to make mistakes, and therefore needing protected from this by mechanical devices such as tokens, interlocking, and so on. Perhaps a copy of "Red for Danger" should be put in the post to the German investigators. As I've said before, this is not the first time, in my own recollection, there has been a head-on in Germany, with signals cleared from both directions, due to basic mishandling of things at the signal controls.

One thing that also strikes one is the sheer complexity and quantity (and cost) of signal equipment on what is a secondary single line, yet which still doesn't give the protection you get on something like Salisbury to Exeter. When you look at the videos the line looks somewhat like a tramway. It doesn't even seem to be fenced through built up areas.
As I recall, Rolt (the author) emphasises that human falilings are always a threat, and that they can defeat even the most sophsticated engineering set-up; that being said, it emphasises the need for such engineered systems to reduce to the minimum the possibility for human error to cause disaster.
 

30907

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I have to say I can understand where people are coming from re British signalling practice, but the German system is not inherently safe.
Thank you for that very full explanation. I appreciate having someone on the forum who understands both British and German practice, which is impressive.
I think, though, you meant to say NOT inherently UNSAFE (nicht...unsicher)?
 

MarkyT

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Could this be the beginning of the end for human signallers?
With automated route setting and networks increasingly managed from huge centralised control facilities it could be argued the process is already well underway, but there will always be a need for at least a few humans to remain on duty to intervene and make decisions on how deal with unusual occurances and equipment failures etc, even if close to 100% of routine route setting activity eventually becomes automated.
 

EAD

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Thank you for that very full explanation. I appreciate having someone on the forum who understands both British and German practice, which is impressive.
I think, though, you meant to say NOT inherently UNSAFE (nicht...unsicher)?
Thanks - having spent time growing up in Germany as a child my interest in their railways was piqued against a background of a grandfather who grew up with and worked on the GWR/Western Region.

Yes you are correct I meant not inherently unsafe!

Re Sbk - on Drehscheibe there is a debate raging on the use of that short form as it can be automatic block or not (i.e. Selbstblocksignal or selbsttätiges Blocksignal). A full auto block makes sense on a normal twin track line where it will clear to green by default but not where there are always conflicting moves on a single line - however in my view it is there to protect the crossing (as otherwise there would be a crossing signal) and designed to split the block up should you want to flight trains through.

Re comparisons - no I agree they are helpful. The problem is always that different systems start from a different stand point and this is a single track main line - in fact it is a regularly used diversion route to the main line to Rosenheim with heavy freight etc. It is not a secondary line in the German Nebenbahn sense.

Needless to say I am sure when the full investigation is over steps will be taken to tighten up re single lines where this could theoretically happen again.
--- old post above --- --- new post below ---
I think the UK comparisons are quite reasonable.

The difference is that the German approach regards the signal staff as infallible provided they follow the rules. The British approach has long regarded the staff as the opposite, bound to make mistakes, and therefore needing protected from this by mechanical devices such as tokens, interlocking, and so on. Perhaps a copy of "Red for Danger" should be put in the post to the German investigators. As I've said before, this is not the first time, in my own recollection, there has been a head-on in Germany, with signals cleared from both directions, due to basic mishandling of things at the signal controls.

One thing that also strikes one is the sheer complexity and quantity (and cost) of signal equipment on what is a secondary single line, yet which still doesn't give the protection you get on something like Salisbury to Exeter. When you look at the videos the line looks somewhat like a tramway. It doesn't even seem to be fenced through built up areas.
Ah Red for Danger - long time since I read that. No I agree in comparisons and the emphasis. Full interlocking etc is in use here and generally in Germany as the world copied our approach. The issue is how the signalman is meant to handle an emergency situation and there I agree they will need to look at the rule book, workload etc. Keep in mind in the late 90s the job at Kolbermoor was done away with and the panel there moved to Bad Aibling under the signalman there. That of course removed the additional layer of having two humans have to agree with the situation in terms of occupancy.
 

BRX

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It's hard to understand how he made such a seemingly obvious mistake but I feel for the signaller. His life probably ruined as a consequence of one lapse. I'm glad that the mistakes I'm liable to make in my job don't generally have the potential for something like this to result.
 

AlexNL

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Today I have seen some articles questioning the distress signal which was sent out by the signaller. Germany seems to have a lot of areas where GSM-R reception is flaky at best, or totally nonexistent.

There seems to be an area of about 400 metres at the start of the block section at Kolbermoor, which would explain why the GSM-R emergency signal was not received by one of the trains.

http://m.welt.de/vermischtes/article152414596/Notruf-ins-Leere-Funkloch-auf-Ungluecksstrecke.html
 
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EAD

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Today I have seen some articles questioning the distress signal which was sent out by the signaller. Germany seems to have a lot of areas where GSM-R reception is flaky at best, or totally nonexistent.

There seems to be an area of about 400 metres at the start of the block section at Kolbermoor, which would explain why the GSM-R emergency signal was not received by one of the trains.

http://m.welt.de/vermischtes/article152414596/Notruf-ins-Leere-Funkloch-auf-Ungluecksstrecke.html
Yes there is a known GSM-R patchy area between Rosenheim and Kolbermoor from my understanding, but that would not have impacted the accident location. I can't locate the precise details but in general the whole line is on GSM-R having replaced Zugfunk
 

ComUtoR

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It is most surprising and worrying if the Zs1 signal circuits carry out no opposing route checking at all. The UK PoSA definitely DOES check opposing route locking which as I said before does not release until the train taking the conflicting route has cleared the section.
...‘ ersatzsignal’ signal, which is not interlocked and can give authority to pass a stop signal showing danger when the main aspect cannot be cleared. Unlike the PoSA (proceed on sight aspect) signals in GB, it does not confirm the existence of a wheeled path to the end of the section of line protected, and can be cleared irrespective of a route having been set in the opposite direction...
Without the presence of interlocking I think we can now understand how it was possible.
 

Bletchleyite

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So an otherwise well-designed interlocked signalling system has the ability to be defeated by one person pressing a button, and nothing is there at all to actively prevent him avoiding the correct procedure before he does so, unlike (if MarkyT is correct) in the UK.

Quite astonishing.
 
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