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Collision in Germany

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Re: Collision in Germany

Unread postby Frank » Fri Mar 11, 2016 11:27 am

Hello,

sorry, you a wrong

the Bavarian system relies upon the Signal Block System to prevent head on collisions. This did not work.


1.
It is not a Bavarian System, its origin came from Token system in GB.

2.
Block System works well, the Signals in Bad Aibling where locked.

But you need a option, if a failure is present on the Line (and that is also for the High-Tec ETCS).
This option is so old as the Railway Signaling, to give the Train Driver a Order (also in ETCS).
It is then on the Signal Man to check out that everything is okay.

And here he failed.

What he did is clear not why and that two times.

What he did:
a) set Route Kolbermoor to Bad Aibling with pressing Signal Button (Start/N) and Line Button (Ziel/X) at the Kolbermoor Part on his Panel.
With that the automatic System Blocks the Signals in Bad Aibling direction Kolbermoor and also the Block Signal 313 (Streckenblock/Line Block).
see here in Flesh:
https://de.wikipedia.org/wiki/Datei:Bah ... rk,_1.jpeg
(Below the red light ist the Zs1 -Subsidiary Signal)

b) a little later he tried to set the Route Bad Aibling to Kolbermoor.The Route comes in but the Signal remains in Danger,because it is locked from
Kolbermoor.
And now the Mistery begins.......at first a little Arrow on the Panel show the Signal Man, that a Train is coming from Kolbermoor (Line Block) and at second
himself sets this Route.

Until now it is all in a safe state.Signal in Danger and without permission the Train could not pass it because that is locked by the PZB plus the Overlap.

But the Tragedy starts with the poor Signal man gives Order Zs1 to Train.
The Train proceed to Bad Aibling Kurpark, the next Passenger Stop and comes there to Stop again.The Automatic Block Signal 313 is locked too.
From the other direction the Automatic Block Signal 314 is in Danger,too because the Train at Bad Aibling Kurpark occupies its Block section to Bad Aibling.

And now the fatal mistake of the Signal man happend, he gave Zs1 again,so the Train moved on and unfortunally the other Train from Kolbermoor
is short (a 100 Meter) behind the Distant Signal to the Block Signal 314 when the Collision happend.


But why he did it is the great Mistery.
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Re: Collision in Germany

Unread postby Andrew Waugh » Sat Mar 12, 2016 11:06 am

I think what Culburrarail is trying to ask is why the signalling system doesn't require the route through the single line section to be set all the way into the next loop. That is, the signaller at Bad Aibling would have had to set a route from the entry signal into Bad Aibling from the single line section before a route could be set from Kolbermoor into the single line section. This would have made the accident far less likely, as the points being locked in position for the arriving move would have prevented the signaller from clearing the Zs1 signal for the departing move from the other track.

I'm not actually sure of the answer, although it is a standard approach, and not just in Germany. I can think of several answers. One is a limitation of technology. Requiring an entry route to be set at one station before an exit route can be set at the previous one could require additional line wires between crossing loops. Relay interlocking practice that I'm familiar with treats each crossing loop interlocking independently, with the control over the single line typically being by some variant of APB. A second answer is that this locking restriction would mean that the signaller would have to commit to a route at the advance station much earlier than otherwise would have been the case. (In this context, it should be remembered that German crossing loops are normally signalled bi-directionally so that the signaller at Bad Aibling would have a choice about which track to route an incoming train.)

A second issue is the provision of the Zs1 indication on signals leading into single line sections. In Victoria, we have the equivalent of Zs1 on Home signals. Home signals are normally fitted with a low speed head and can display 'low speed caution' (points are detected locked for the route, but track circuits may be occupied, so proceed on sight). Like the Zs1 indication, this allows a signaller to easily authorise a movement past a Home signal held at stop due to a track circuit failure. However, in Victoria these low speed lights are NOT (*) provided on Home signals that lead into single line sections. The reason, of course, being, that the track failure might be a train coming the other way. If a Home signal leading into a single line section fails at stop, the signaller has to authorise the driver to pass the signal using a paper order. This takes time, and the advantage of time is that dangerous situations can resolve themselves (i.e. the opposing train can clear the single line section, or the signaller notices the opposing train) or someone questions what is going on.

(*) for the sake of completeness, I should note that some Homes controlling the entrance to a single line section also control movements into sidings. Low speed heads are then provided, but can only be cleared with the route set into a siding. I should also note that the restriction on providing low speed heads only applies to single line section, it does not apply to bi-directionally signalled tracks in station yards.
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Re: Collision in Germany

Unread postby Andrew Waugh » Sat Mar 12, 2016 11:17 am

Frank wrote:b) a little later he tried to set the Route Bad Aibling to Kolbermoor.The Route comes in but the Signal remains in Danger,because it is locked from
Kolbermoor.


When you say 'the route comes in', do you mean that the interlocking allowed the route to be set from the exit signal at Bad Aibling over the loop exit points (presumably to the Bad Aibling entry signal) even though an opposing route was set over the single line? And the white 'route set' lights illuminated? If so, this would be a horrible trap for a signaller. I'm sure I must be misunderstanding you.

Frank wrote:But the Tragedy starts with the poor Signal man gives Order Zs1 to Train.
The Train proceed to Bad Aibling Kurpark, the next Passenger Stop and comes there to Stop again.The Automatic Block Signal 313 is locked too.
From the other direction the Automatic Block Signal 314 is in Danger,too because the Train at Bad Aibling Kurpark occupies its Block section to Bad Aibling.

And now the fatal mistake of the Signal man happend, he gave Zs1 again,so the Train moved on and unfortunally the other Train from Kolbermoor
is short (a 100 Meter) behind the Distant Signal to the Block Signal 314 when the Collision happend.


So the signaller gave the Zs1 signal to the train twice at successive signals. I suspected that was what must have happened.
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Re: Collision in Germany

Unread postby Frank » Sat Mar 12, 2016 10:43 pm

Hello Andrew,

that
When you say 'the route comes in', do you mean that the interlocking allowed the route to be set from the exit signal at Bad Aibling over the loop exit points


is corect.
That is a philosphy at Panel Boxes Type Spurplanstellwerk for having route locking if for example a Block Failure or else is on the Line.
Because the Signals are still locked.
For you as a Signal man that you know from the education and the Panel Signs.Then you have to check out why it happend.



I think what Culburrarail is trying to ask is why the signalling system doesn't require the route through the single line section to be set all the way into the next loop


That isn`t usual here, because with that Procedere you Lock a Station for a long Time, espacially on greater Stations there where most of the Movements blocked then (Shunting etc.) .Also we have a divide between the LInes and the Stations.



So the signaller gave the Zs1 signal to the train twice at successive signals. I suspected that was what must have happened


Exactly that happend and is a mistery... :(

Because on the Panel ist the permission Block Sign, a yellow Arrow that shows him that himself had set a Route from Kolbermoor.
The Automatic Line Block on this Panel Boxes ist a two System Block. The First ist the permission Block (Erlaubnisblock) and the second is the normal
Line Block.
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Re: Collision in Germany

Unread postby Culburrarail » Sun Mar 13, 2016 4:37 am

Yes I was investigating why the system failed from an interlock clash problem knowing nothing about the system and gleaning data from this site and news releases.
I have put together from various sources available on the internet the following sequence of events and fairly solid times.
At 06:40 a Train 79506 arrives at Kolbemoor. The signal man sets its route to Bad Aibling knowing that the train 79505 is running late. The timetable calls for this train to depart at 06:45.
At 06:42 The Signal man operates the ZS 1 signal enabling the Bad Aibling train (79505) to proceed past the Red Signal.

The conditions for the crash to occur are now set up.

I now offer some assumptions and ask questions of the German experts upon the Signal Block System and the Relay Board in use.

The signal man controls a large portion of the tracks south of Munich between Koltzkirchen and Rosenheim. Just where the Relay Panel is located is not known to me.
The time of day is the start of the morning rush hour. The signal man probably has many trains to control. He may have been a holiday relief as it was a Festival day. He probably intended to cancel the route set for the Kolbermoor train after he activated the Zs 1.

Would the Signal Block System and the relay panel allow him to do this as there is now a train occupying the track?

Did the signal man expect the presence of train 79505 on the Block to prevent train 79506 from entering the Block?

We know that the Kolbermoor train entered the Block with a green signal at 06:45. We know that this would have illuminated a section of the signal mans relay panel. We are told he tried to use the radio to contact the drivers separately. We don’t know the times when he did this. We know he did not use the 299 emergence code to alert the drivers to the imminent danger.

If he had used the 299 emergency code, would that have applied to the two trains that crashed or to all the trains under his control?

Where on the line are the Signal Block System signals that could have stopped either train?

We know there are two sets of crossing signals within the Block, are these part of the Signal Block System or just local control?
Is the Signal Block System smart enough to know in which direction trains are travelling within its Block?
I guess we will have to wait for the enquiry results to be published to fully answer these questions.
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Re: Collision in Germany

Unread postby Culburrarail » Sun Mar 13, 2016 5:12 am

I think Frank is wrong as the signal man gave the Zs 1 while the train 79506 was still stationary in Kolbermoor or perhaps just about to start off.
It was after the train 70506 entered the block from Kolbermoor that the poor man realized his mistake and by then there were no signals on the line to prevent the accident. But why did the signal 314 at Kolbermoor remain green after the signal man gave the Zs 1 on Signal 313 to train 79505 and it entered the Signal Block?
Could this be my 'Deadly Embrace' situation with both trains entering the block at essentially the same time?
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Re: Collision in Germany

Unread postby Andrew Waugh » Sun Mar 13, 2016 10:52 am

Frank wrote:that
When you say 'the route comes in', do you mean that the interlocking allowed the route to be set from the exit signal at Bad Aibling over the loop exit points

is corect.
That is a philosphy at Panel Boxes Type Spurplanstellwerk for having route locking if for example a Block Failure or else is on the Line.
Because the Signals are still locked.
For you as a Signal man that you know from the education and the Panel Signs.Then you have to check out why it happend. [...]

Because on the Panel ist the permission Block Sign, a yellow Arrow that shows him that himself had set a Route from Kolbermoor.
The Automatic Line Block on this Panel Boxes ist a two System Block. The First ist the permission Block (Erlaubnisblock) and the second is the normal
Line Block.


Thanks Frank. It's very interesting as the panel behaviour sounds very different to what I'd expect in Australia (and what I'd expect in the UK from my reading).

Linking this back to an earlier discussion about the operations of the panel and the indications shown, my understanding the sequence would have been something like this...

The signaller sets the route from Kolbermoor. Once the points are detected for the movement, the white route lights will be lit from the exit signal at Kolbermoor to the intermediate automatic (protecting the level crossing). The route lights will not be lit in the second portion of the single line section as the intermediate automatic is held at stop by the level crossing. Block indicators will be lit on the panel (at both Bad Aibling and Kolbermoor) to show that a route is set from Kolbermoor to Bad Aibling. The signal at Kolbermoor will clear (and be shown as clear on the panel).

Some time later the signaller attempts to set the route from Bad Aibling. The exit points will run and when the points are detected for the movement the white route lights will be lit from the exit signal to at least the entry signal. Would the white route lights also light in the single line section to the other intermediate automatic? The exit signal will not, of course, clear.

The signaller assumes the Bad Aibling exit signal has failed at stop. They are looking at a panel that's showing white route lights set from the exit signal, possibly all the way through the section or possibly with a couple of sections dark. The signaller misses the block indicators and the exit signal at Kolbermoor at clear.

I'll have to ask around locally to find out how local panels would act in this situation.
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Re: Collision in Germany

Unread postby Frank » Sun Mar 13, 2016 11:19 am

Hello Andrew,


yes, there we have many differences also to our mechanical Boxes.

On mechanical Boxes there where Home Positions for Points and Catch Points, this means you have a permant Route lay in .
A View over the Locking frame and you see everything is o.k.
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Re: Collision in Germany

Unread postby edwin_m » Sun Mar 13, 2016 2:05 pm

In the UK context, would a PoSA aspect be permitted for a route leading to a single line (or a bi-directional line used occasionally in the "wrong" direction?). And if so would it be possible to illuminate the PoSA if a route was set onto the single line from the other end?

There must always be a tradeoff in the use of degraded modes of operation such as the PoSA, Zs1 and Zs7. A system that provides a greater degree of safety in the degraded mode is more likely to be rendered useless by the failure that caused degraded mode to be necessary in the first place, requiring the use of a safe "backup of backup" mode of operation.

If an aspect of this type can only be lit when the route and points are set and locked then it will provide a workaround for track circuit failures, which are probably the most common type of failure but are generally safe for trains to pass on line of sight (excluding broken rails and provided, as mentioned above, the "failure" is not a train moving in the opposite direction). It will not provide a workaround for point failures, but these would normally require someone to go to the trackside to set the point and confirm its setting locally, so this type of failure would still result in considerable delay whether the "degraded mode" was available for use or not.

But there is also some complication relating to route locking. In UK practice if a track circuit shows occupied this will lock any route that was set over the track at the time the failure occurred, from the location of the failure to the overlap of the exit signal. This in turn locks any points on that part of the route and therefore prevents a train proceeding on any route that requires those points to be set differently. The only way round this is either to clear the original fault or to move the points manually from the trackside. The degraded mode signal could then only be used after that if it didn't depend on the points being detected in correspondence with how they were called by the interlocking. I think a degraded mode aspect on the signal protecting a single line would inevitably be in this situation if a track circuit failure occurred with a route set in the opposite direction - and if the degraded mode cannot be used when an opposing route is set (including part of a route after a track circuit failure as above) then it will become useless in at least 50% of track circuit failures on a single line.

So there is some reasoning behind the practice of the interlocking providing relatively few controls that would prevent the Zs1 being used, since it allows the Zs1 to cover for more types of failure. However this inevitably leads to greater safety risk when it is used. In the light of this accident the question is whether the correct balance has been struck between safety and availability.
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Re: Collision in Germany

Unread postby Frank » Sun Mar 13, 2016 10:02 pm

Hello edwin_m,

In UK practice if a track circuit shows occupied this will lock any route that was set over the track at the time the failure occurred, from the location of the failure to the overlap of the exit signal. This in turn locks any points on that part of the route and therefore prevents a train proceeding on any route that requires those points to be set differently.


This is here the same, but only in Stations.
For understanding,on Relay Boxes Type SpDr here there is a divide between the Line and the inner Station.On the Panel you have both displayed,
but the handling is different.

In the Station you could not set a Route over a occupied (or failed) Track that belongs to that Route.
From the Station to the Line you could set a Route even if the Line is occupied (so called Nachlauf /Follow-up stored by the Relay System ) .
When the Blocking back from the Line (next Block) came in, then the Signal go to Proceed.
On Single Lines there is the speciality that there is a second Block System, the Erlaubnisblock /Permission Block.He locks all Signals
against the direction of the travelling Train.


That
In the light of this accident the question is whether the correct balance has been struck between safety and availability


mayb be a point.
In the Older Days a Signal man had to call the next manned Box to ask witch Train with Taillamps are arrived there before he could use the Zs1 (or write a Train Order).
But with the more and more ongoing Centralisation (ETCS) the Rules where changed.Now the Signal man has to proof it on his Panel.
Here a video from the Holzkirchen Box at Upgrade by the S&T
https://www.tegernseerstimme.de/sobald- ... 01142.html


The Signal man of Bad Aibling controls on his Panel his Station (Bad Aibling) and the Stations Kolbermoor and Heubling.
Next manned Boxes are Rosenheim (direction Bad Aibling to Kolbermoor) and Holzkirchen (direction Bad Aibling to Heubling).
That all Single Lines and so the Mistery is there,because he had every the Day the same illumintions on his Panel and must know them very well.
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Re: Collision in Germany

Unread postby Culburrarail » Tue Mar 22, 2016 4:32 am

I have been working hard on the operating problems concerning the Bad Aibling to Kolbermoor railway single track. While it is not usual to consider such a small section of a single line system I determined that any proposed solution to the Bad Aibling-Kolbermoor section would equally well apply to the entire line.
I came up with two alternate proposals that would improve the safety features while still allowing the required flexibility that is allowed the Signal Man in choosing which line to use within the station blocks.
Both proposals required two extra Signals and modification to the Route selection and its interlocks and to the Signal Block System.
When I studied the logic block diagrams it was obvious that there would be considerable expense involved.

HOWEVER!

When I added the Zs 1 system to the proposals I found that it was still possible to make decisions that would end up with two trains facing each other on the single track section of the line if not actually crashing into each other.

In conclusion my only suggestion is that Signal Men should have more stringent rules that apply to the use of Zs 1 overrides and that they require written Train Movement Orders be passed to the train drivers.
I will watch out for the results of the enquiry and court case into this tragedy to be published.
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Re: Collision in Germany

Unread postby Fast Line Floyd » Tue Mar 22, 2016 9:39 am

Culburrarail wrote:I have been working hard on the operating problems concerning the Bad Aibling to Kolbermoor railway single track. While it is not usual to consider such a small section of a single line system I determined that any proposed solution to the Bad Aibling-Kolbermoor section would equally well apply to the entire line.
I came up with two alternate proposals that would improve the safety features while still allowing the required flexibility that is allowed the Signal Man in choosing which line to use within the station blocks.
Both proposals required two extra Signals and modification to the Route selection and its interlocks and to the Signal Block System.
When I studied the logic block diagrams it was obvious that there would be considerable expense involved.

HOWEVER!

When I added the Zs 1 system to the proposals I found that it was still possible to make decisions that would end up with two trains facing each other on the single track section of the line if not actually crashing into each other.

In conclusion my only suggestion is that Signal Men should have more stringent rules that apply to the use of Zs 1 overrides and that they require written Train Movement Orders be passed to the train drivers.
I will watch out for the results of the enquiry and court case into this tragedy to be published.

Or alternatively don't allow such moves with the Zs1 onto a single line but instead use either a written form or a human pilot as we do in the UK.
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Re: Collision in Germany

Unread postby kbarber » Tue Mar 22, 2016 9:44 am

Culburrarail wrote:I have been working hard on the operating problems concerning the Bad Aibling to Kolbermoor railway single track. While it is not usual to consider such a small section of a single line system I determined that any proposed solution to the Bad Aibling-Kolbermoor section would equally well apply to the entire line.
I came up with two alternate proposals that would improve the safety features while still allowing the required flexibility that is allowed the Signal Man in choosing which line to use within the station blocks.
Both proposals required two extra Signals and modification to the Route selection and its interlocks and to the Signal Block System.
When I studied the logic block diagrams it was obvious that there would be considerable expense involved.

HOWEVER!

When I added the Zs 1 system to the proposals I found that it was still possible to make decisions that would end up with two trains facing each other on the single track section of the line if not actually crashing into each other.

In conclusion my only suggestion is that Signal Men should have more stringent rules that apply to the use of Zs 1 overrides and that they require written Train Movement Orders be passed to the train drivers.
I will watch out for the results of the enquiry and court case into this tragedy to be published.


In other words, the extra expense offers no significant improvement (perhaps no improvement at all) in safety in the face of a failure of the human element. Which I think is where we came in.

The rules applying to the use of the Zs1 aspect are already pretty stringent and the requirement to account for incrementation of the counter offers a further check.

I wonder if you've read the preceding postings fully. It has been pointed out that the Zs1 indication was created precisely to avoid the need to issue written orders; with a degree of connection to the interlocking it offers an incremental improvement in safety over written orders (which don't ensure points in the line of route are set and therefore introduce a further human element). But written orders don't guarantee, any more than the Zs1, that a single line is clear. So an accident such as this remains possible regardless of the particular system you use.

The only way to absolutely prevent an accident of this kind is to completely ban all overriding of the interlocking system in case of failure. As I said above, the inevitable consequence of that is complete paralysis of the entire system as every minor failure leads to trains held for many hours at red signals with no possibility of movement until repair is complete and fully tested. The consequence of that is that passengers will inevitably desert the railway in favour of road transport. You will have achieved an absolutely safe railway - on the day it closes. But the overall causalty figure will rise because road transport is already far less safe than rail and road traffic willl be further increased (with consequent increase in accident rate and severity) by the increased traffic.
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Re: Collision in Germany

Unread postby Fast Line Floyd » Tue Mar 22, 2016 10:31 am

kbarber wrote:
Culburrarail wrote:I have been working hard on the operating problems concerning the Bad Aibling to Kolbermoor railway single track. While it is not usual to consider such a small section of a single line system I determined that any proposed solution to the Bad Aibling-Kolbermoor section would equally well apply to the entire line.
I came up with two alternate proposals that would improve the safety features while still allowing the required flexibility that is allowed the Signal Man in choosing which line to use within the station blocks.
Both proposals required two extra Signals and modification to the Route selection and its interlocks and to the Signal Block System.
When I studied the logic block diagrams it was obvious that there would be considerable expense involved.

HOWEVER!

When I added the Zs 1 system to the proposals I found that it was still possible to make decisions that would end up with two trains facing each other on the single track section of the line if not actually crashing into each other.

In conclusion my only suggestion is that Signal Men should have more stringent rules that apply to the use of Zs 1 overrides and that they require written Train Movement Orders be passed to the train drivers.
I will watch out for the results of the enquiry and court case into this tragedy to be published.


In other words, the extra expense offers no significant improvement (perhaps no improvement at all) in safety in the face of a failure of the human element. Which I think is where we came in.

The rules applying to the use of the Zs1 aspect are already pretty stringent and the requirement to account for incrementation of the counter offers a further check.

I wonder if you've read the preceding postings fully. It has been pointed out that the Zs1 indication was created precisely to avoid the need to issue written orders; with a degree of connection to the interlocking it offers an incremental improvement in safety over written orders (which don't ensure points in the line of route are set and therefore introduce a further human element). But written orders don't guarantee, any more than the Zs1, that a single line is clear. So an accident such as this remains possible regardless of the particular system you use.

The only way to absolutely prevent an accident of this kind is to completely ban all overriding of the interlocking system in case of failure. As I said above, the inevitable consequence of that is complete paralysis of the entire system as every minor failure leads to trains held for many hours at red signals with no possibility of movement until repair is complete and fully tested. The consequence of that is that passengers will inevitably desert the railway in favour of road transport. You will have achieved an absolutely safe railway - on the day it closes. But the overall causalty figure will rise because road transport is already far less safe than rail and road traffic willl be further increased (with consequent increase in accident rate and severity) by the increased traffic.

Quite so Keith but a written order does force some thinking time into the equation which is lacking in the use of the Zs1.
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Re: Collision in Germany

Unread postby JRB » Tue Apr 5, 2016 9:06 am

Something a friend put to me: Why didn't the driver ask the signalman the reason for the Zs1? "Our West Highland drivers always query anything unusual with the Banavie signalman."
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