2010 Aspect Sequence

[Peter]

I don't think that we have quite got the filing sorted out yet; the link Peter placed to the one that couldn't be found but he said he had moved to "higher up the thread" doesn't take me anywhere other than an error message.......

I think I must have been online just when you were posting that - I found the error and sorted it and it works now, but it must have been just after you tried.

Peter

[libracpy]

May I ask any comment for our practice?

Thanks

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May I ask any comment for our practice?

Thanks

Sorry, the attachment was missed in the last post due to bmp file format.

[PJW]

My comments at the moment aren't going to be very helpful I am afraid.
The thread is 2010, the file says 2010, the diagram itself says 2011 which is obviously a typo unless you have a sneak preview of the coming exam, but the signal numbers don't match with 2010.

To save me playing "hunt the layout" (107 is quite a common number to use), could you tell me which year it really is?

OOPS, I have just remembered that last year they drew a specific layout in the Q paper rather than the layout 3; I'll look it out and then respond

May I ask any comment for our practice?

Thanks

---

May I ask any comment for our practice?

Thanks

Sorry, the attachment was missed in the last post due to bmp file format.

[PJW]

A few small things; starting from the bottom

107CC displays R + PL + 'MI' B.
20s seems rather long for only 100m track BAC, for a track of that length you may not need any time value at all. You'd have done better to have chosen say a 200m berth track

107BC. You have drawn it reading to R in the box for 111; being a call-on it does not prove the aspect ahead so this was superfluous.
Also need to be careful where you label the approach release; it certainly seems you are labelling to the left of the vertical line for 107CM and CC so it seems to be that it is 107BW rather than 107BC that is approach released.
I think it is better just to annotate #1, #2 etc and then put the text elsewhere; it saves such confusion where little space and also may save writing if several are the same.

107BW. Seems that the ROL is at least as long as track BAC (which certainly justifies your assumption of 100m); if that is the case then the Delayed Yellow would just clear on BAC occupied (no time).

107AM. You decided to show YY up to 121 at Y; it could of course have been G but in these circumstances it seems a reasonable decision.
You wrote Y+P1, YY+P1, G+G1 so I assume that last is a typo.

This is where your answer went a bit wrong because you seem to have shown the approach release dashed line horizontally which makes no sense. There should be a solid line back from 107 at Y+P1 back to the FY on 105; the approach release is of 107 FROM YELLOW (the hint is in the name!) so the dashed line should be vertical and connect the YY+P1 and G+P1.
The aspect line should be solid all the way back to 103; it is 107 which approach releases after the train has passed the FY.

The other error is the vertical dashed line at 103 which means nothing and indeed it should be a solid line connecting to give a G on 101; from your chart it looks as if 101 shows Y to 103 initially at R that then magically changes to FYY at some unspecified time.

Not sure why you selected 10s for the time on BAC; it would be the same time as you'd use for MAR on 107 (it is the need to see the PLJI no later than the main aspect).
That is the other omission; you showed no MAR on 107AM for circumstances in which the flashing aspects can't be shown to a train.
Which brings me to the fact that you did not explain any of the flashing aspect controls; true these do not always feature on an aspect sequence chart but it'd be wise to at least outline them on an IRSE Exam paper. In particular do you consider it would be appropriate to display a flashing aspect sequence at a time that 121 is at red?

I'd also direct you attention to the wording of the question; it wanted "an explanation of any assumptions or controls you have included". I don't feel you did this, so however well you did the chart, there would be a significant quantity of the marks that you couldn't get.

The aspect sequence chart used to be a regular, then disappeared for a few years and it was made clear that its re-emergence was likely not to be "standalone" but as part of a written question. Indeed in 2010 it was quite a minimalist chart compared with previous years, so it should be obvious examiners were after more.

Therefore I think it is reasonable to expect there will be a need to do more than just the chart in 2011 and subsequent years, so do be careful when reading the question.
There were hints at the last exam review that the same policy may be adopted in mod 5 for the TC calc question, so as ever READ THE QUESTION CAREFULLY

Also look on the first page of this thread and you'll find a link to an example re how to flashing aspects depicted for a real job.

May I ask any comment for our practice?

Thanks

[Peter]

In particular do you consider it would be appropriate to display a flashing aspect sequence at a time that 121 is at red?

I was going to say the same thing, but then I looked at GK/RT0045 which says in section 5.2.3.6

A flashing aspect sequence shall only be displayed when the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal that displays the flashing single yellow aspect and one of the following applies:
a) The first signal beyond the diverging junction is a controlled stop signal that is either one of the following:
i) Displaying an OFF aspect
ii) Displaying an ON aspect and a forward route is set
iii) Displaying an ON aspect at the end of a loop line or platform line where all trains are expected to stop
b) The first signal beyond the diverging junction is an automatic signal
c) The first signal beyond the diverging junction is an isolated distant signal
d) The train protection system is configured to mitigate the SPAD risk at the first stop signal beyond the diverging junction.

Given the layout beyond 121, I assume that condition b) applies. a)iii) may also apply.

[PJW]

Indeed; I was very much aware and thus I worded it as what I hoped was an open question to provoke the thought process.

I expect the scenario was intentional and that the examiners expected the candidate to justify it one way or another within the explanation they specifically called for as part of this question.

Broadly after Colwich, there is concern about the driver misunderstanding the meaning of FY. The exception re the auto signal is because:
1. It would often be impracticable (excessively costly) to implement
2. The risk associated with a SPAD at such a signal is low (not very likely to be at red anyway, at worst a rear-end collision).

The exception re a passenger platform is because (and it is really assuming a platform with pointwork beyond it in the station throat rather than the plain line type station that we have here) there are quite a lot of sites when the operating department really want a flashing aspect to signal into the platform loop line (Birmingham International station springs to mind). However it is likely that the exit signal will be at red since another train may being signalled out of the parallel platform or indeed there is a fast train just behind the one entering the loop which is about to overtake it. Balance of Safety and Operability again; although to be fair it can also be argued that the risk of confusion re what a FY might mean isn't significant if the driver is expecting to stop at the station anyway whatever aspect sequence is given.

It is my experience that we [OOPS sorry NR, the railway I now work for doesn't have any flashing aspects and is trying to get rid of lineside signals altogether] generally apply the control unless there is a good reason not to do so; hence even though the signal is an auto, if it were SSI then would almost certainly do so. Every one is quite risk adverse and it is sometimes just easier to do it than run the risk someone else will come along just before commissioning (such as a CIP) and decide that it should have been imposed.

In particular do you consider it would be appropriate to display a flashing aspect sequence at a time that 121 is at red?

I was going to say the same thing, but then I looked at GK/RT0045 which says in section 5.2.3.6

A flashing aspect sequence shall only be displayed when the approaching train is detected to be in a position that is compatible with the required reading time of the junction distant signal that displays the flashing single yellow aspect and one of the following applies:
a) The first signal beyond the diverging junction is a controlled stop signal that is either one of the following:
i) Displaying an OFF aspect
ii) Displaying an ON aspect and a forward route is set
iii) Displaying an ON aspect at the end of a loop line or platform line where all trains are expected to stop
b) The first signal beyond the diverging junction is an automatic signal
c) The first signal beyond the diverging junction is an isolated distant signal
d) The train protection system is configured to mitigate the SPAD risk at the first stop signal beyond the diverging junction.

Given the layout beyond 121, I assume that condition b) applies. a)iii) may also apply.

[Peter]

Indeed; I was very much aware and thus I worded it as what I hoped was an open question to provoke the thought process.

Sorry, I though that this might have been the case just after I posted it. Sorry to spoil the opportunity....

[PJW]

No problem; it served to expose the issue and the fact that to have done either would not have been wrong, provided that the explanation justified the decision.
Whichever decision the candidate made, the examiners would have learnt that they indeed knew the rules and could make a rational decision based upon their reasonable assumptions about the circumstances.

As ever there is the "question as written" which is the canvas on which the candidate is to paint a picture of their knowledge and experience, and
the "question the examiner is really trying to find the answer to": does this person convince me that they are competent in this module's element of S&T engineering- do they have the requisite attitude, skills, knowledge and experience?

Indeed; I was very much aware and thus I worded it as what I hoped was an open question to provoke the thought process.

Sorry, I though that this might have been the case just after I posted it. Sorry to spoil the opportunity....

[libracpy]

Dear PJW and Peter,

Thanks a lot for your both valuable comments. Most of them can be understood and so I am trying to review my practice. My practice is really based on 2010 Q10 and the title of 2011 is a typo. However, I still have some questions and hope to have any feedback if available.

1) For 107B©: ....."Also need to be careful where you label the approach release; it certainly seems you are labelling to the left of the vertical line for 107CM and CC so it seems to be that it is 107BW rather than 107BC that is approach released."
{Of course 107B(W) will have approach release based on definition. Should I present 107B© also has the approach release by the Control Table: "AR" given in the question? The same reason is also applied for 107C©}

2) About the assumption for flashing yellow, originally I just think it is normal practice for "MAY-FY" and no specific assumption is required. Since my working environment only require Main class route and Shunt class route, the knowledge to handle "MAY-FY" is quite "fresh" for me and so it is required to learn from external sources or UK standard.

[PJW]

A Warning class route is always approach released, how severely depends upon the length of the ROL beyond the signal to which it reads.
Only in the case of a bare minimum 45m ROL is it as severe as for the call-on, more typically the train speed need only be reduced to saround 25mph. Hence for IRSE Exam purposes make the time for a Warning route less than any call-on for the same berth track length.

A Call-on route is always severely approach released, the train needs to be "at or nearly at a stand" and hence no more than 100m from the signal.

Hence I'd perhaps have asumed a longer berth TC than you did, perhaps time for 5 sec for the W and 20 sec for the C. The two C routes would use the same time value.

2. To be honest this question really was very NR specific. To me the IRSE claim that students can use any practice with which they are familiar isn't always true in practice; there are some questions which would be best avoided by those without the specific knowledge. There is no getting away from it, this question couldn't really be answered to any other practice.
I suppose to balance that :
a) to some extent there are a few questions, particularly metro related that people from NR would best avoid,
b) at least the Railway Group Standards can be downloaded for free from the internet and the Study Pack includes a lot of other information, so there is at least the availability for someone anywhere to teach themselves enough to answer such questions in the exam.

Dear PJW and Peter,

Thanks a lot for your both valuable comments. Most of them can be understood and so I am trying to review my practice. My practice is really based on 2010 Q10 and the title of 2011 is a typo. However, I still have some questions and hope to have any feedback if available.

1) For 107B©: ....."Also need to be careful where you label the approach release; it certainly seems you are labelling to the left of the vertical line for 107CM and CC so it seems to be that it is 107BW rather than 107BC that is approach released."
{Of course 107B(W) will have approach release based on definition. Should I present 107B© also has the approach release by the Control Table: "AR" given in the question? The same reason is also applied for 107C©}

2) About the assumption for flashing yellow, originally I just think it is normal practice for "MAY-FY" and no specific assumption is required. Since my working environment only require Main class route and Shunt class route, the knowledge to handle "MAY-FY" is quite "fresh" for me and so it is required to learn from external sources or UK standard.