2009 Q7 TRAIN OVERRUN SIGNAL

[PJW]

Note that this is one of the questions considered in the official IRSE "Sample Answers"

[ricky]

Hi All,

I had a look at this yesterday with my study 'partner'. We were along the same lines as the previously submitted answers so there is no point submitting a full answer but there were a couple of questions that came up we would like your feed back on.

The question states a train enters an occupied section. Now I read this to mean that there was a train already in the section. However could this also be interpreted to mean perhaps there was a fallen tree or supermarket trolley etc. How would you interpret occupied? Is it a train being there, something being there or something detected as being there. If the tree falls and shorts the track is that different to not shorting the track? Or is this unnessacary nit picking?

2ndly who would investigate an inccident such as this. My first thought was RAIB which I still beleive to be correct, I subscribe to there website and I can understand how they work but they don't attribute blame. Others do attribute blame as NR have had a couple of payouts recently due to LXing deaths, it this done by British transport police?

Finally would the approach to investigating be more focussed or open minded. Would the investigator say this was the likely cause lets check for that and take it from there or would it be a general approach covering all the bases? If I take this question example for in cab CCTV may show the driver passed a red aspect and therefore would rule out any trackside or interlocking issues as the cause, saving a lot of time and money in testing.

Thanks for the support

[Jerry1237]

As with all of these questions, I would qualify your assumption and be specific on what you are defining occupied as.

Incidents and accidents on rail are investigated by the police firstly and the RAIB following on from that. Others may be involved depending upon the severity.

The police are concerned with crimininal investigations. Their evidence may be used by the ORR (H&S procecutions), the coronor etc.

The RAIB collect evidence to identify the root causes and failures of the incident/accident. These are used to drive policy changes, make recommendations that could improve 'safety' etc.

Investigations, such as SPADs, can be shortened if the driver admits making a mistake. Abnormal aspects etc., have to be investigated to provide assurance the signalling system is behaving as designed.

The simple answer is there isn't a simple answer. All investigations are unique and depend on what has occured and if people are injured.

Finally, the BTP are not quite the same as the mainstream police.

Hope the above helps.

[PJW]

Certainly to me it definitely means occupied by rail vehicle and almost certainly by one of a type that one could reasonably expect to be detected. The definite inference is that the signal should have been at red and there is no suggestion that the train was authorised procedurally to pass it (because the driver's claim is of a proceed aspect).
Hence
# tree = NO
# supermarket trolley = NO
# car / lorry / bus etc = NO
# rail engineering trolley = assume not but could perhaps stretch it to include
# tamper = possible (a possible cause of the event could be the inability of the vehicle to present a sufficiently low shunt resistance and thus the track circuit remaining up)
# train = YES.

In general one should interpret the question as widely as possible, but since the wording was "occupied" rather than "obstructed" and the question is clearly focussed on whether a SPAD occurred or an invalid aspect was shown rather than the reason for the obstruction being there, then I would simply have stated as an assumption: "occupied section interpreted as meaning by a previously authorised train movement" which would still permit such causes as an axle counter having been reset invalidly with a vehicle left there after engineering work, yet discount the fallen tree, crashed road vehicle, barricade erected by vandals, herd of cows etc that I think lie outside the subject area of this question.

I think Jerry has responded to the other parts of the question; I'd just say that
a) the police are often first on the scene of an accident and are interested in a scene of crime and securing the evidence (even if they actually sometimes inadvertently destroy or fail to capture because of lack of technical understanding),
b) the RAIB then arrive and carry out investigations focussed on lessons to learn, looking at trends, investigating whole incident widely, not seeking to attribute blame. Reports take a long time to be published, but elements are often drip fed in advance and this can result in actions being taken and the various parties doing some associated inquiry,
c) generally is a parallel investigation- indeed this may have started under the auspices of the police prior to RAIB. Indeed it does depend on the seriousness of the incident- there may well not be an RAIB investigation at all. In this case for example there could have been no accident at all, the train may have passed the signal and stopped well short of the first train perhaps due to the action of TPWS, so the actual risk relatively low and there would be no involving of the police at all and the RAIB would probably only be interested in hindsight statistically unless they had reason to believe that this was not an isolated incident.
Hence does depend on circumstances.
d) eventually there may be a public enquiry for serious accidents and this is where the lawyers all get involved and therefore blame attribution is inevitable. Obviously to back up the respective cases of the parties involved other investigations etc can be initiated, which themselves can cast more light and thus be assimilated as another strand of evidence in the RAIB investigation. A case that springs to mind is Potter's Bar points; the information relating to a history of nuts working loose on adjustable stretcher bars at many sites over a significant time emerged quite late after the accident and I think as a result of certain parties defending their positions.

However whenever anyone is investigating any incident should always keep mind open and examine all the evidence and consider various possibilities- not just find a bit of evidence that seems to back up the initial assumption and consider that was definitely the cause. Obviously though one does focus attention- if there are several bits of evidence all pointing the same way and the most obvious alternative explanation all have evidence against them, then that is a reason for gradually excluding them and seeking to ensure that the incident can be fully explained by the scenario which is being considered the overwhelmingly most probable.

If you read almost any RAIB report you will see that they go much further- even if fully convinced that the incident is explained and various elements of the evidence gathered are not relevant to the actual occurrence of the accident, if they find other things that are not perfect (in the real world they almost certainly always ill if they look hard enough) then they will comment or even make recommendations about them even if it is clear that it had no bearing on the immediate cause, root cause, likelihood, severity, mitigation etc of what actually happened. The iceberg argument; whilst they have "lifted the lid" looking at a typical bit of the real world in microcosm, if they think there are other unrelated lessons to be learned then they will highlight them in that report.

The question states a train enters an occupied section.
Now I read this to mean that there was a train already in the section. However could this also be interpreted to mean perhaps there was a fallen tree or supermarket trolley etc. How would you interpret occupied? Is it a train being there, something being there or something detected as being there. If the tree falls and shorts the track is that different to not shorting the track? Or is this unnecessary nit picking?

[PJW]

This is one of a set of three answers undertaken in mock exam conditions; eventually I have found the time amongst other priorities to respond- sorry for the time it has taken! (Just getting you accustomed to waiting for IRSE exam Results......)

a)
Good coverage. 

I think I would have explicitly stated putting in some protective signalling disconnections (if practicable to do so in a manner that unlikely to destroy evidence).
In this scenario don't forget the equipment onboard the train- most OCs now have forward facing CCTV and all must have On Train Data Recorders.

May also  have been worth up front stating some assumptions about the signalling  (panel / VDU, any TD, any ARS?; Interlocking: RRI / CBI; type of colour light signal, type of train detection, level of train protection provided etc.) as that would have given context to your whole answer as influences immediate action / evidence preservation / possible causes.

b)
Not really enough for 10 marks here.  Items 4 and 5 were meaty enough to stake a claim for 2 marks each, but think the first three a little thin.  I would have tried to make them more different and added a bit more detail-
1  re-worded more to suggest that the driver knew he had SPADed having encountered the Red unexpectedly having missed the distant or having been distracted and was actually knowingly lying about the aspect to try to cover up
2. I'd have made more obviously that the driver honestly thought they had received a proceed aspect but had made a mistake at looking at the wrong signal due to reading across or reading through etc. 
3. Phantom aspect so driver did really see what they took to be a proceed aspect even though all the signaling equipment evidence apparently refuting that.  Consider route indicators as well as the main aspect.

However I might have wrapped all these up in one major bullet, having each as sub bullets.
Having made a meaty first cause under the broad heading of "driver error", I would ten have had another of "signaller error" with by far the most likely for this alleged incident being the inappropriate reset of an axle counter. 

Your item 4 covers "maintainer error" but I'd have added a second sub bullet about not detecting deterioration (such as cable insulation) to supplement the one you included about an active error creating the fault.

Your item 5 covers both "new works application design & test" errors and equipment faults and I think I'd have separated as being different causes; the comment re train detection wrongside failure was worthy of being more than an after thought.  Of course nowadays even certain axle counter products are regarded as being able to give false clearance of a section for a significant time period.......


c)
Your last section started well enough, but since you ran out of time it is not clear whether it was really developing into the requested procedure though. 
There was probably a bit too much overlap with the first part of the question re the initial acquisition of evidence, rather than describing what one does to "manage the investigation" and the techniques to try to sort the relevant from the irrelevant, the reliable from the unreliable, piecing together the various sources to obtain a holistic picture in order to convert data into knowledge an extract learning from the incident. 

Didn't really get on to the two scenarios in the last sentence to a meaningful extent.

A bit unfortunate that you also used numbers for the paras in the last section as it took me a re-read to realise that those quoted in them actually referred to the causes in the first section rather than to each other in this part!

Hence overall I think you might have got

• 4 marks for the first section,
  
• 6 marks for the second, and
  
• 4 marks for the last.
  

Definitely a respectable pass but I felt that you weren't getting far enough into section c) before the time ran out.

Worth looking back at the earlier attempts in this thread and indeed the IRSE's sample answers that are referenced higher up; interesting the candidate's answer that they commented on also had a relatively weak last section and they suspect that shortage of time may have been the issue for them as well.......