2010 CTs, points 137 & 148

[SARVESH KUMAR]

Sir,

Please check my point control table of IRSE 2010 for point no. 137 & 148

WITH REGARDS
SARVESH KUMAR

[Peter]

Sir,

Please check my point control table of IRSE 2010 for point no. 137 & 148

WITH REGARDS
SARVESH KUMAR

Your post says about 137 and 148, but the attachment only has 148.

Not a bad attempt - you got most of the obvious stuff. A couple of things were there but in the wrong place and there are some things that you have missed.

No deadlocking tracs shown for R>N.
481B(S) requires them N not R
The overlap for 484 goes beyond the crossing between 148A and 148B, so by the same logic that you have included the routes from 484, you also need to include the route from 494 up to 484 which requires the overlap.
Not sure why you have included FK in the locking release after 482.
Probably the biggest area of error is where you have incorrectly looked at the routing for trains from 461, 463 and 465. For 461, you have taken the train diverge through the switch diamonds! (You may need to look up about switch diamonds) The route goes though 137R. Similarly, 463 and 465 cannot go via the diamonds, they go via the relevant bits of the ladder reverse. That said, if it were possible to go the way you sent it, the route locking release that you put would have been correct.

One point that I am not sure on (because I am a bit rusty and have not looked it up) is that I think there should probably be some time of operation locking on the points with routes up to 481. Perhaps someone using this in their day job can comment straight off.

Hope this helps.

Peter

[Peter]

Ah, I think I have now found your other post for 137. Can you please make sure you put them in the appropriate section? I have now moved it to here and will hopefully someone will be able to look at this shortly. Note that I have already put comments on 148 here.

[SARVESH KUMAR]

Sir,

Please check my point control table of IRSE 2010 for point no. 137 & 148

WITH REGARDS
SARVESH KUMAR

Your post says about 137 and 148, but the attachment only has 148.

Not a bad attempt - you got most of the obvious stuff. A couple of things were there but in the wrong place and there are some things that you have missed.......

One point that I am not sure on (because I am a bit rusty and have not looked it up) is that I think there should probably be some time of operation locking on the points with routes up to 481. Perhaps someone using this in their day job can comment straight off.

Hope this helps.

Peter

thanks sir
from
sarvesh kumar

---

Ah, I think I have now found your other post for 137. Can you please make sure you put them in the appropriate section? I have now moved it to here and will hopefully someone will be able to look at this shortly. Note that I have already put comments on 148 here.

thanks sir

from
sarvesh kumar

[PJW]

Well I don't do this for my day job either, but....

148A tips are very close to the commencement of FJ track which commences just beyond 481 signal, so clearly if there were to be a SPAD and the points had just been called they could potentially be half way across when the train gets there; hence Time of Operation locking look sensible.
To set against that though the only moves up to 481 are PL moves: proceed as far as the line is clear, no faster than 15mph, so one could argue that there is no absolute requirement (I don't have access to NR's current standards). Given that any even minor derailment here would foul the Up Branch, then personally I would certainly provide.
Certainly from IRSE Exam perspective then I definitely would or at least put a note of your rationale for non provision.

Sir,

Please check my point control table of IRSE 2010 for point no. 137 & 148

WITH REGARDS
SARVESH KUMAR

Your post says about 137 and 148, but the attachment only has 148.

Not a bad attempt - you got most of the obvious stuff. A couple of things were there but in the wrong place and there are some things that you have missed..........

One point that I am not sure on (because I am a bit rusty and have not looked it up) is that I think there should probably be some time of operation locking on the points with routes up to 481. Perhaps someone using this in their day job can comment straight off.

Hope this helps.

Peter

[PJW]

Re 137 CT

I think the problem was not so much with what was there, rather than for the items missed. To be fair, it is a complicated layout and I do wonder whether it exceeds what it should be expected from a student in an exam, but that's the paper and you must do your best with it.

There were some surprising omissions. Whereas you listed 465C, you didn't include 461C or 463C which look the more obvious.

The biggest omission was you regularly failed to get all the flank- for example 137A provides flank for moves over 138B normal.
So 471A, 474D, 471C, 473B, 472D, 472E ........

You also didn't see that 137B are trailing points in the overlap beyond 473 (an arguably 471 but I'd state the assumption that no swinging overlap provided here), so 455B

Sir,

Please check my point control table of IRSE 2010 for point no. 137 & 148

WITH REGARDS
SARVESH KUMAR

Your post says about 137 and 148, but the attachment only has 148.......


Hope this helps.

Peter

thanks sir
from
sarvesh kumar

---

Ah, I think I have now found your other post for 137.
I have now moved it to here and will hopefully someone will be able to look at this shortly.
Note that I have already put comments on 148 here.

thanks sir

from
sarvesh kumar

[Tony Soprano]

137 Dead Locking....

Would N>R not also require (CK or 141R) given the position of the CP near 137B points?

Also can the possiblity of AF & EM tracks being foul {(AF or 138N) & (EM or 136N)} be excluded from the dead locking if these points will always be called flank by the route?

[PJW]

Indeed CK is certainly foul and thus should lock as you describe.

On a layout such as this, I would probably expect to find point-to-point that would prevent 138 N>R unless 137R or 136R; prevent 137 R>N unless 138N. This would be the traditional way of signalling the area. Nowadays more likely to achieve much (but not exactly) the same by pure point calling by the relevant routes.

Whether or not it is worth AF locking 137 is a matter of debate. Dead track locking is primarily for hand-signalled moves and if AF were occupied with vehicle on 138B reverse, then whether train being handsignalled over 137N or 137R it is equally likely to hit it. Therefore from that perspective there is little 137 can do about it one way or another.
A train on AF would lock 138 so this would prevent to route being set up applicable to 137R, but not for one applicable to 137N. So could well decide that (AF or 138N) should lock 137R>N and largely therefore analogous to the locking that would have occurred via the point-to-point.

To be honest I don't know what the current practice would now be. I'd be tempted to omit so that 137 could be put N, because that would at least enable normal working on the Up Slow. However you are certainly not wrong to include it, and you may feel this is the wise thing to do in the IRSE exam.

Signal engineers can argue about the finer points of locking for ages; there is often a balance to be struck between one risk and another, or slight greater safety at the expense of significant operability.
For the examination it is more important to get the basics right and I try to pitch my comments on attempts to be appropriate to the level of the author, though yes I should have pointed out that CK is conditionally foul, so thanks for your comments

137 Dead Locking....

Would N>R not also require (CK or 141R) given the position of the CP near 137B points?

Also can the possiblity of AF & EM tracks being foul {(AF or 138N) & (EM or 136N)} be excluded from the dead locking if these points will always be called flank by the route?

[Tony Soprano]

[The overlap for 484 goes beyond the crossing between 148A and 148B, so by the same logic that you have included the routes from 484, you also need to include the route from 494 up to 484 which requires the overlap.]

When an overlap extends through a set of points like 148 do you have to include these extra tracks as part of the route release for 494 signal i.e. EL track circuit?

So ignoring the swinging overlap
Route-----Tc's clear-------------Occ---t
494A(M) - EK, EL, (EG, EH, EJ..... EJ....20s)

Any secondly if we encounter a swinging O/L do we have to condition this into the release (something like)
Route-----Tc's clear-------------------------------------Occ---t
494A(M) - EK, {(EL or 146R),(CJ or 146N)}, (EG, EH, EJ..... EJ....20s)

Doesn't look right (as it probably isn't) but there doesn't seem to be any real benefit in including TC's (EL or CJ) passed the dead locking tracks. Could we not just release all point locking associated with 494 once EL becomes clear after having been occupied (which would presumably only happen after a SPAD?)

Think I've lost the plot on this a bit.

Cheers

[PJW]

I guess you are now referring to 148 points which I haven't looked at before, but yes it is certainly usual to provide flank protection for overlaps as well. There are circumstances when we don't but in this case setting and locking 148N for 494 routed to 484 would not be in anyway restrictive, so I would do it. Proving 148 detection though isn't so clear cut as a point detection failure would necessitate handsignalling from 494 and I think the modern view is that could be the greater risk. However in this particular case it isn't just flank- it is also trapping from shunting moves, so in this scenario I'd certainly detect, though this could perhaps be "at time of clearance only".

When you are talking about the route release for 494 what I understand you to mean is the "maintained locking after 484 used"; the route release would occur by EG clear after EG, EH occ provided that the route had been cancelled and aspect relay proved de-energised.
I am not quite sure whether you mean the locking imposed on
a) the points or
b) opposing routes (as not exactly the same).

I'll assume the former.
There is no value in listing any tracks beyond 484 as the tracks ought to be dead locked by EK anyway. Even with SSI there is no track bob protection for overlaps so including overlap route locking gives nothing extra over the dead track locking. The only time that you'd list is where there is a track beyond the signal that does not deadlock because the point end is in the second or subsequent track.

If you were thinking about the application of locking to an opposing move (not that there is one here as the Up Branch is uni directional), then yes you would list all the tracks within the overlap. However you wouldn't list both lies of the points in the overlap since any opposing route would require those points either the one way or the other; obviously only need to worry about the opposing move for the lie of the points which is compatible with the route. I suppose one could envisage a very odd layout where two routes opposite direction routes shared overlaps that had two parallel facing crossovers that acted as swinging overlaps for both; in that case one would have to put the opposing route locking entry in twice, once coupled with one lie of the swinging overlap points and the other overlap tracks listed in conjunction with the opposite point availability- I would really hope that this sort of thing wouldn't feature in the IRSE Exam (and suggest best avoided in real life too).

[The overlap for 484 goes beyond the crossing between 148A and 148B, so by the same logic that you have included the routes from 484, you also need to include the route from 494 up to 484 which requires the overlap.]

When an overlap extends through a set of points like 148 do you have to include these extra tracks as part of the route release for 494 signal i.e. EL track circuit?

So ignoring the swinging overlap
Route-----Tc's clear-------------Occ---t
494A(M) - EK, EL, (EG, EH, EJ..... EJ....20s)

Any secondly if we encounter a swinging O/L do we have to condition this into the release (something like)
Route-----Tc's clear-------------------------------------Occ---t
494A(M) - EK, {(EL or 146R),(CJ or 146N)}, (EG, EH, EJ..... EJ....20s)

Doesn't look right (as it probably isn't) but there doesn't seem to be any real benefit in including TC's (EL or CJ) passed the dead locking tracks. Could we not just release all point locking associated with 494 once EL becomes clear after having been occupied (which would presumably only happen after a SPAD?)

Think I've lost the plot on this a bit.

Cheers