Solved 2009 Control Table

[Indira]

Hi PJW,

Please find attached file and correct it.

Regards,
Indira

[Peter]

I have not looked at the detail of your CT content, but had a quick look at you attachment and note that the template for the table has a company name on it. This may seem an odd thing to point out here, but remember that he instructions from the office about using your own template specifically states that they should not contain anything of this sort. I would hate for you to turn up at the exam and have your templates disallowed, so make sure the sheets that you take with you comply with the requirements.

Peter

[PJW]

It will be tonight before I have a chance to look at this. Actually the scan isn't very clear and so perhaps for the exam it would be worth getting a softer pencil (in the UK we would call a 2B for example) that makes a wide, darker line. The problem is that these do go blunt quickly, so best off taking several.

Hi PJW,

Please find attached file and correct it.

Regards,
Indira

[Peter]

I am really sorry, I settled down to have a look at your attempt and find that the only copy I have of the layout is a very bad scan from which it is almost impossible to see the numbers properly. I paper copies of most layouts, but 2009 is missing from that pile too.

I'll see if I can get hold of one and have a look later.

Peter

[PJW]

I am really sorry, I settled down to have a look at your attempt and find that the only copy I have of the layout is a very bad scan from which it is almost impossible to see the numbers properly. I paper copies of most layouts, but 2009 is missing from that pile too.

I'll see if I can get hold of one and have a look later.

Peter

Actually I have just started to look at this one!

[PJW]

Starting with an overview of 416B(M):
1. There are few if any marks in the exam for filling in boxes such as "Route Disable" even if you get right; you risk losing marks though if you fill in incorrectly.
a) I don't see that 416B(M) would have Auto working
b) It certainly would have a permanent and an electro AWS
c) it would have a fitted TPWS. Assuming you are compiling to NR modern new works standard (you have not stated) then the TPWS almost certainly would be indicated.

2. You have used some $ notes but have not defined them.
a) Assuming again that you intended to use as per NR practice, then the $7 for DE in the aspect level is a frill you can probably do without for exam purposes. By putting the same entry in the row below which applies to aspects better than Yellow suggests that you do not understand; it is superfluous if it is already included above; a yellow is a pre-requisite for any less restrictive aspect,
b) the $16 applied to BP makes no sense; it is not a track being used when it is occupied to provide a release in an adjacent interlocking needing to be proved clear in the controls of a rear signal. Again the use as you have suggests that you do not understand and you'd have been better off to have omitted.
c) $37 applied to points in the aspect; how do I as an examiner know that you understand the significance?

3. Point availability- You need to be careful with your use, well actually non-use, of brackets. Without them all the conditions prior to the "or" form one alternative and all the entries afterwards form the other. You surely did not mean that; for example 246 is required as FLANK for the route, irrespective of the overlap which is set. You needed an [ prior to 237 and the corresponding ] after 236. In fact it would have been clearer to have written:
[(237, 234 ....................235)
or
(232..........................237, 236)]
before continuing with other points which are always tested.
The inner brackets ( ) do not change the expression algebraically, but certainly avoid the risk of misinterpretation when an expression spans several columns and joined with dots / dashes.

The outer brackets [ ] in the expression are essential to prevent all your later entries being part of the "or" expression.

Actually if we now look at those later points:
239N- is only needed when 237N
249N- is arguably not essential (it may be a case for a soft call) but it is certainly independent of 237
246N- is needed as flank independent of 237
238N- is only needed when 237R
Hence 239 and 238 should have been added into the relevant part of the bracketed expression.

That's a shame because overall it looked as if you understood a swinging overlap but spoiled it by some slap-dash presentation.

4. Opposing Route Locking.
a) 416B has an associated call-on route; you forgot to cross-lock this one.
b) You need to consider all routes which have exit 405; you seem not to have seen the GPL signal routes.
c) Depending on whether you are doing these CT's for an RRI or a CBI (I do not know because you haven't stated your assumption), but if the latter then the opposing locking from 356B and 351B should probably include the first overlap track BP since this still opposes and yet the point availability could be satisfied (depends on what we assume about 243's locking but I think that they might be free)
d) The opposing locking from the call-on moves should take the locking as far as BR (at least). It matters not to 416B(M) whether the earlier train sitting in the platform entered by a main or call-on route- the fact remains is that if it is still there then there is no chance of the aspct for 416 clearing and thus the route should not set. If we were doing the CT for 416B© then that would be different....
e) For 351B you missed out a track circuit BV; oops that is a wrongside failure and potentially we lose all the point locking ahead of the train, so small error with big consequences. Do take care that you are aware of each block jint that the train crosses and that for each you find the track name; the fact that the train's path does not actually pass the "ID label" is no excuse for missing out the track section.
f) Why list 365A as an opposing route? It is quite at liberty to be set when 416B sets via 237N; that is why we have a swinging overlap. You are correct that it is incompatible with the overlap over 237R, but that is achieved by the locking that 365 places on points 236 which is contrary to where our route needs them to be free to move towards.

5. Aspect level points.
Similar comments as before really. I wouldn't detect 249 even if you decide to make it a hard call- set and lock.

6. Aspect level tracks clear.
Use of brackets is correct here. Expressions look reasonable but hard to say for sure given ambiguity re the point entries. BU would be foul of the overlap via 237R but is probably covered adequately by the 238 condition written within the points box.

7. Aspect level tracks occupied.
If you look at the route box you'll see that this route is specified to be MAY, actually MAY-FA. Therefore, amongst other things, you should have shown appropriate approach release conditions which should include
a) the fact that DB is initially clear and that 422 is off and ready to start flashing
b) the "hold-off" which means that once 422 is flashing that the subsequent occupancy of DB and indeed the subsequent replacement of 422 as a train passes it does not result in the premature reversion of 416's aspect
c) the fact that there should be only one attempt to set up a flashing sequence for each train movement; should it fail then the signal must revert to MAR,
d) the MAR requiring that 416 shall not clear until the PLJI becomes readable to the driver no later than the main aspect of the signal, unless the driver has been shown a flashing yellow on the approach,
e) You also need to consider whether there is also need for 378 to be off for the flashing sequence to be established;either you ought to include it or at least state an assumption and give argument why control isn't required. Given that there would be an overlap which locks out the relevant conflicting moves (or at least all the high risk ones) and 378 is at the end of the platform then there may be a case for omission; however the track layout does have some similarities with COLWICH.....

8. Aspect sequence and misc row.
Already made some comments relevant to this.
378 would have TPWS as protects conflicts and this would be proved in 416B(M).
The special controls / remarks box is probably the best place to show all the controls that don't fit conveniently elsewhere associated with aspect clearance in conjunction with the flashing yellow in rear..
The track occupied box would show the conditions (the same as in the box above for MAR) when the signal, having in this instance started at Y+PLJI pos 4) can step up to a higher aspect once the train has gor reasonably close and can see the whole signal together- I guess that there should be a time for the DE occupation (and the $7 is certainly not needed here, although DE$7 above would be the means of a technician disabling the MAY_FA feature and always force a restrictive MAR).
I would also use that box to write in some SPAD overrun controls; the route is vulnerable to SPADs at 412, 407, [(376, 374) w 237N], [(365, 371, 353, 351) w 237R]

9. Approach Locking- Comprehensive.
OK broadly.
Actually I think should make clearer by drawing horizontal line under each line of entry to associate DE, DC with the dash, DB with the 422 etc. To be very picky, then 422 and 424 are auto signals so really cannot be On and free of Approach Locking. Either you would not bother to condition out or a kind of pseudo A/L provided "signal not cleared since passage of last train", but for exam purposes I wouldn't worry about it.

10. Remainder of route releasing.
OK.
Wouldn't bother with TORR as relatively few places have it and IRSE don't seem to expect or give any marks for it.

SUMMARY.
I have written a lot and possibly missed a few things but hope I have given good impression of how your answer would be judged.
Actually overall not too bad, yet you can see that on the other hand you probably didn't do as well as you thought you might have done.
Given where we ae re proximity of the exam, I recommend d=not worrying too much about the things that you may not know too much about 9e.g. flashing aspects) and concentrate on tightening up on the things that you can rectify quickly by a bit of tightening up.

A.
Strip out the non-essential entries in the Control Table blank; you need to hide the company name so also hide all the boxes that will cost you time to fill, are wrong to leave blank yet won't gain you marks if you do complete.

B.
Make sure you understand the correct use of brackets and Boolean operators

C.
Tighten up your understanding of opposing route locking. This is a key area and you will lose marks badly if you miss out routes and again if you put in superfluous ones. This route was not one that tested you hard, yet you had instances of each failure; suggest you practice these and check the various past paper attempts on this website. Look for
i) routes exiting on the approach to the CT's signal
ii) routes exiting within the route of the CT's signal
iii) routes exting within the overlap(s) of the CT's signal
iv) overlaps which conflict with the overlap(s) of the CT's signal
Then for each route exit, make sure you list all the "parallel signals" which share that as an exit, with the exception of any which are otherwise prevented by locking points the wrong way.
Beware indirect route locking.
Beware overlaps which time off.
Beware that the CT's for M and W routes differ from C and S in situations in which the opposing route can time to a stand.

D.
Make sure you state your practices, clarify any assumptions and define any $ notes that you use. If in doubt, probably better to leave out as if used wrongly you'll lose more than you could hope to gain from having utilised.

Provided you do the above and don't take too log to complete them, then you should pass the CT question as this was quite a nasty one. Remember if you can get it over half right then you get the pass mark. Unlike real life, the exam does not need perfection.
Just try to avoid too many silly errors, particularly those that result in a serious wrongside failure.


Having, I thought, finished that route, I took your second sheet of paper to look at the next one. The first thing which struck me was that there was little on it- I guessed you had run out of time. i then looked to see which route it was; i was surprised to find that it was the same; i.e. that you had a continuation sheet.
OK I would now go back and amend my comments for the things I thought you had missed but had put here; however I decided not to do so. This way you can see what is going through the examiner's mind-
a. How was i supposed to know that the first sheet was not complete in itself and demanded a continuation> On checking back, there was NOTHING.
b. How do I know that I have all sheets of this candidate's work?
I DON'T. The pages are numbered- but both of them say 1. I have no idea of the total number of sheets either per route or per the whole question / module.
LEARN FROM THIS!
(but I now withdraw some of my earlier comments which are addressed by this second sheet).
Obviously EC is a flank track control as a basic means of mitigating a SPAD at 412 (but why did you only do that here?), but I don't think you meant DE (what did you mean?)

Hi PJW,

Please find attached file and correct it.

Regards,
Indira