Answers to 2002 Part A Q1 & Q2

[PJW]

Is entering Overrun Protection required as part of the exams as the 202 tables do not have them?

It is up to YOU to declare YOUR practices- there is no fixed link between IRSE and current NR although I must admit that the layouts are very mainline UK (but actually pretty much 1970s / 1980s).

Agreed the 11202 CTs do not have specific box; they reflect 1980s which was a time when the pendulum had swung away from providing flank tracks and before the reaction to certain accidents caused it to come back into favour again, albeit in a slightly amended form as Overrun Protection. They are very out of date for various reasons being implicitly for RRI but actually nowadays used almost exclusively for SSI; actually part of my day job is to revise them and yes there will be such a column that will make reference to a dedicated Overrun Control Table where all the gory detail will be shown. Indeed such sheets already exist for various sites and are frequently cross referenced from the Remarks / Special Controls column of 11202.

So IF you declare CURRENT NR practices then you should include. If you declare British Rail then you should not. I realise that as an individual who are having to learn foreign practices purely for an exam then you don't know where to turn. Don't worry too much; it isn't basic locking where the marks really are. In one way it is a frill; however I do suggest that it is worth including somewhere, the primary reason not being the actual marks you'd get but BECAUSE IT'LL PROBABLY GET YOU TO REALISE THAT YOU HAVE MISSED CALLING POINTS FLANK and there are goodly marks for those.

[alexgoei]

Hello Peter,

I am not sure if I understand why 206R is entered as a condition here and would like to suggest two reasons why as a test of my understanding which perhaps you can say whether I am right or wrong.

For route 114 B(M), there are two routes leading to it: One by 122A(M). Hence when 114 is put back to Danger, 118 will be yellow and hence like you say this can be seen from track BR. The second route is via 122B(M) then 116 A(M); hence 206R a condition for this.

Is my reasoning correct?

Dinner time now. Don't let me hold you up if you do not find me on line

Thank you and Regards

[PJW]

Hello Peter,

I am not sure if I understand why 206R is entered as a condition here and would like to suggest two reasons why as a test of my understanding which perhaps you can say whether I am right or wrong.

For route 114 B(M), there are two routes leading to it: One by 122A(M). Hence when 114 is put back to Danger, 118 will be yellow and hence like you say this can be seen from track BR. The second route is via 122B(M) then 116 A(M); hence 206R a condition for this.

Is my reasoning correct?

Dinner time now. Don't let me hold you up if you do not find me on line

Thank you and Regards

No.
You need to consider the lookback in various portions.

Firstly from the signal itself to each of the signals in rear- this is the "first section". It will generally consist of a list of tracks but with point conditions if any of the signals read anywhere else than our signal. In this case we have BL, BM, BN (AN or 205N). In this case where there is no route from 116 over 205N then the condition on AN is arguable but probably worth including so that 114's locking is not held by a train on AN that has come from 109/113. Older installations did not "store" that an intrusion had occurred within the CAL area and thus the point condition less critical; nowadays then should be included as one a train has been "seen" then the CAL path is permanently inhibited for RRI sites (CAL is performed at instant entrance button is first pulled for SSI sites).

Secondly you must consider the various "section in rear"; in this case there is the behind 118 and behind 116 sections to consider.

Thirdly in a 4 aspect area only you must then consider the "second section in rear" i.e. all those sections back to the signals that would diesplay YY when our signal reverts to Red. In some cases these signals can be the same (although different routes obviously) for the various first signal in rear (i.e. there are multiple paths from the outer signal to the CT signal via various of the intermediate signals); in other cases where two entirely separate lines converge at a geographic junction then obviously the second signals in rear are entirely different.

Our case has two first sections to consider;
118 for which BP and BR are relevant. BR is only relevant though if 206N; therefore we write it: BP, (BR or 206R). i.e. just like when you have a conditionally foul track for a set of points you initially "assume the worst" and put the track in the locking, then you "get rid of it again if there is a valid "excuse reason"" by putting in the or condition. BR should lock 114 UNLESS 206R, therefore we write (BR or 206R). If we wrote the "positive "BR w 206N" it would imply that we'd actually need to have achieved Normal detection of the points to IMPOSE the locking and this could give a wrongside failure if the points lost detection; that is why we put the converse "require BR clear unless we have positive proof that the train will be deflected away from approaching 118".

For the section depedent upon 116 not being ARAFOAL we could put AP, AR (BR or 206N); however my argument before was that they'd be no need to take the lookback that far given that the aspect displayed at 122 routed to 116 would at best have been yellow and hence my expectation that 116 would be at red until AP became occupied anyway.

I think it is the concept of writing the point positions in the "unless the converse is true" rather than the "when in the correct position" which is confusing you

[alexgoei]

Hello Peter,

Thank you for the reply.

Your explanation now makes it clearer. I will use it to test my understanding on other examples.

I must say that this is very different on how this is presented with the British Rail Control Tables notes (page 15) which you sent me. If I used BR practice for the same example of 114 then under Approached Locked When Signal Clear and Tracks OCC the entries will be:

BL, BM, BN
(BP w 205N)
(BR BS w 206N 122 USED)
(AN AP w 206R 116 USED)

Is this correct and can I use this? Really choosing what is easier to understand and apply.

For the matter on Overrun Protection, my Notes Applicable will say "UK Mainline practice (approx year 2000) adopted..." so presume will take care of that. But good to just think of it and include Points Normal or Reverse for flank protection.

Thank you & Regards

[PJW]

Hello Peter,

Thank you for the reply.

Your explanation now makes it clearer. I will use it to test my understanding on other examples.

I must say that this is very different on how this is presented with the British Rail Control Tables notes (page 15) which you sent me. If I used BR practice for the same example of 114 then under Approached Locked When Signal Clear and Tracks OCC the entries will be:

BL, BM, BN
(BP w 205N)
(BR BS w 206N 122 USED)
(AN AP w 206R 116 USED)

Is this correct and can I use this? Really choosing what is easier to understand and apply.

For the matter on Overrun Protection, my Notes Applicable will say "UK Mainline practice (approx year 2000) adopted..." so presume will take care of that. But good to just think of it and include Points Normal or Reverse for flank protection.

Thank you & Regards

Indeed there are different presentations, sometimes dependent upon technology. If you find that one an easier one to use then follow it- the N in that situation would infer "points set and locked" not "set locked and detected" and that may be something to include in your General Notes.
This is why it is difficult for someone who doesn't really use any particular standard but tries to pick up information from various sources- I must admit that I was looking at your CTs on the basis of how I thought you'd have learnt at Signet.
Not convinced by what you wrote (I'll have a look later at the notes to see what they were actually saying) , but you could certainly write-
BL, BM, BN (AN w 205R)
section in rear 118: [BP, (BR w 206N)]
section in rear 116: [AP]

Yes if you declare c2000 then you need not put in the Overrun Protection explicitly (though I still recommend just thinking long enough about it to make sure that you haven't overlooked flank point calls).

Remember above all success in the exam is about speed and getting the basics for all the routes- do not worry too much about getting everything 100% right.

[alexgoei]

Hello Peter,

What I was taught I Signet was to list the track circuits back to the first yellow signal. The course did not cover entries with respect to points or what I mentioned with respect to the BR Notes. I picked up from your bite size notes on reading back to the first yellow signal depending whether 3 or 4 aspect.

If you do not get round to retrieving those notes, I will quite gladly send them over to you so that you receive them first thing Monday morning UK time. Just indicate in your reply to me.

Good night. Have to turn in now as I was involved in some night exercises on the railway that saw my day ending at three thirty this morning.

Regards

[PJW]

Hello Peter,

What I was taught I Signet was to list the track circuits back to the first yellow signal. The course did not cover entries with respect to points or what I mentioned with respect to the BR Notes. I picked up from your bite size notes on reading back to the first yellow signal depending whether 3 or 4 aspect.

If you do not get round to retrieving those notes, I will quite gladly send them over to you so that you receive them first thing Monday morning UK time. Just indicate in your reply to me.

Good night. Have to turn in now as I was involved in some night exercises on the railway that saw my day ending at three thirty this morning.

Regards

Going back just one signal section will not in general be enough- however, depending on the CT style, it may be that these are the only track circuits actually listed BUT there would ALSO be a cross reference to the relevant signal-in-rear CTs to give the details of "their" section.

Whatever you think of this as a way of depicting, you can't adopt this unaltered for the IRSE exam because it is unlikely that you'll be producing the relevant other CTs- you need to show ALL the relevant locking for the specified routes so you can't cross reference to sheets that you are not providing with your answer.

If you had been taught a presentation without point conditions then I think it'd have treated every approach to the signal as a separate entry
e.g. on one line of entry- BL, BM, BN, AN after 116A used
on the next line of entry- BL, BM, BN after 118A used
i.e. some of the tracks are included in multiple lines of entry where they are common.
I seem to remember that the "CP9's" showed like this. Personally I never liked that way (and since BR quickly abandoned them it seems I was not alone); primarily because that wording suggested that route locking was involved and the locking was dependent on the route having been set- this was never the case and indeed should not be (so that approach locking is applied to a signal that has been cleared and visible to a driver undertaking a handsignalled move up to it).
Certainly I'd avoid depicting like this in the exam (you can hardly take a form of presentation that was used in the 1980s if you are declaring your practices are c2000....). It is also likely to take up too much space if many signals in rear.

Looking at page 16 of the "Derby training school notes" to which I think you are referring, I can see why you are confused. For similar reasons as above I feel the "route used" is inappropriate for a condition on a track beyond that signal (though I am more comfortable with it for those tracks on that signal's approach- I still feel "or ARAFOAL" is more accurate but accept "when route used" is more readily comprehendable). I'd argue that "BH 104N 15 used" is rediculous- (if 15 used then 104 will be set and locked N so that would not need stating).

You "pays your money and takes your choice", but in this area I wouldn't advise following those notes. I emphasise though that the examiners will primarily be looking for the provision of CAL when applicable and ensure that the extent is taken sufficiently but not excessively far.
I'd recommend going back as far as the overlap joint beyond the closest signal that would not change aspect (i.e. approach lock before it might be possible for a driver to see an aspect become more restrictive as the CT signal is placed to Red).

[alexgoei]

Thanks Peter,

Was just about to send you a scanned copy of page 16.

Will digest your comments.

[PJW]

Thanks Peter,
Will digest your comments.

Text from 11202:
[b]Approach Locking Applied when Signal Clears [or Attempts to Clear or to Show a Route Indication] and Track Circuits are Occupied OR

[alexgoei]

Hello Peter,

With reference to CAL for 114 B(M), I find your reply:

BL, BM, BN (AN w 205R)
section in rear 118: [BP, (BR w 206N)]
section in rear 116: [AP]

clear so will it be OK if I use this as an entry for Approach Locked, When Signal Clear and TC Occ.

In addition to these entries, do we need to say ARAFOAL for 118 and 116. Just to be clear.

Thank you & Regards