IRSE Exam Forum

Hello PJW,

Appended please find my attempt on the 2005 layout.

In Part 1 of this thread, I enclose (1) the calculations for Non-Stopping and Stopping and (2) Assumptions, Explanation on the standage for the Freight train and how to turn the engine around and finally the Route tables.

Part 2 will have the attempted layout itself in 5 sheets.

They were still not performed under exam conditions but this layout was done considerably faster than the 2000 layout.

Thank you once again for your time and effort especially your superb turnaround times.

I look forward to your comments

Cheers

Alex

Hello PJW,

This is Part 2 of the posting with the layout on 5 A3 size sheets.

Thank you once again

Cheers

Alex

(11-09-2010, 08:05 AM)alexgoei Wrote: Hello PJW,

Appended please find my attempt on the 2005 layout.

Thank you once again for your time and effort especially your superb turnaround times.

I look forward to your comments
Cheers
Alex

Having a few days holiday so won't be before next weekend I think

(11-09-2010, 02:31 PM)PJW Wrote:

(11-09-2010, 08:05 AM)alexgoei Wrote: Hello PJW,

Appended please find my attempt on the 2005 layout.

Thank you once again for your time and effort especially your superb turnaround times.

I look forward to your comments
Cheers
Alex

Having a few days holiday so won't be before next weekend I think

---

Hello PJW,

Enjoy!

Regards

Alex

(11-09-2010, 08:05 AM)alexgoei Wrote: Hello PJW,

Appended please find my attempt on the 2005 layout.

Thank you once again for your time and effort especially your superb turnaround times.

I look forward to your comments
Cheers
Alex

Calculations:

For the exam you don't actually need to do all the braking calculations you have done. All very well when using a spreadsheet and time isn't of the essence, but in the exam restict yourself to that which you really need. Suggest this is normally just the passenger on the mainline and if there is a branch with a different permissible speed the value for that line as well.

The wording of the question in 2005 was:
Determine theoretically, either by calculation or graphically, appropriate signal spacings for the braking characteristics and the intensity of traffic on offer. All calculations and graphs
must be shown.

Non stopping:
Generally good.
Should have explained the rationale for the 1.33 SBD limit n signal spacing.
You wasted time again by calculating Hd3 and Ht3; effectively doing the same calculation as you had just done backwards and not surprisingly came up with the 125sec value that you had declared in the first place.

Stopping:
Generally good but
a) diagram would have been better if showed the platform,
b) diagram shows braking in portion c commencing at signal 3 whereas your calculations obviously places the transition betwen portion b and portion c significantly past this. To be honest the diagram is really what would happen but that would make c 1095m as it is effectively a signal section but the brakingrate would be less than 0.5m/s/s if decelerating from 100km/h over that entire length. However your calculations assume that driver does not brake on passing 3 and leaves to last minute and thn brakes at maximum rate. This approach makes calculations easier but you should state that this is an approximation and in reality the headway achieved will actually be less (can be part of your rationale for that 20% contingency); certainly the diagram and the calculations must match
c) you should explain the derivation of the 1255m mentioned in your note 2.

Notes
General notes very good.

Working of freight trains etc. Explanation in the exam can be much more brief; I think you have followed my approach when explaining it to students who may not understand; in the exam all you have to do is outline it to show the examiner that you do understand.
I would say something much more compact like:
Freight left in Down Slow platform at C, engine runs around via 121, 305, 122, 116, 301, re-couples and propels train into turnback siding waiting at 122 for a return path to station B.

HOWEVER I don't actually think that is right (above I have described the same move that you did for comparison) in this instance.
a) The turnback siding is fundamentally for the passenger service terminating at C.
b) We have to assume that the freight is originating / terminating at C (unlike the prevous layout you did where it was just needing to change direction to access a different railway line). Hence we must assume that the trin needs to go into / come out of the Down Siding.
Therefore I would say:
Train arrives in Down Slow platform at C; sets back into Down siding utilising 114's PL. After loading, signalled into platform again using 303. Loco detaches and run around via 121, 122, 116, 301 to re-attach and then signalled towards station B from 114.
Looking at station B it is evident that there are no sidings etc. Hence think need to explain to examiners our assumption:
Since there are no freight facilities depicted on the plan at B it is assumed that the freight must be intended to pass through B and continue to somewhere beyond A

(11-09-2010, 08:09 AM)alexgoei Wrote: Hello PJW,

This is Part 2 of the posting with the layout on 5 A3 size sheets.

Thank you once again

Cheers

Alex

Route Boxes

113A(M) Mention Auto facility in comments

113A(W) Approach release is AG occ but don't say MAR as that means Main Approach Release from Red which is applicable to (M) and junction signalling, not (W) routes

117A(M) Wouldn't have a route indicator as it is the straight, highest speed route.

117A(C.) A call-on traditionally always has a route indication to distinguish it from a shunt (well this always was the standard- recently there have been some changes but probably best to ignore for exam purposes!); hence MARI "U".

117B(M) If assume that points 210, 203 & 207 are all 75km/h (again the exam info is somewhat ambiguous but I think that this is what must have been meant) then the SARI should have been PLJI as suitable for greater approach viewing distance and speed.

117C(M) Interseting that you had this as PLJI 5 that would rather imply 117B(M) would have been PLJI pos 4; note that the plan shows no PLJI at all so you have been rather inconsistent! However I agree pos 5 appropriate here.

119A(M) OK. But in the exam if short of time, hardly worth doing signals with only one route.

121A(M) OK

121B(S) Note nomenclature. Actually not convinced that need 305 signal, so would have this read directly into turnback siding.

128A(M) OK

128B(M) Signal ahead is 126 rather than 122- think you must have changed your mind re numbering! Well done for recognising that the junction speed of210, 211 is such that would be MAY-FA. You could have added in the comments box the need for signal 126 to be displaying proceed for MAY-FA to be effective.

122A(M) OK

122B(S) Why have a PL into one platform and a ain aspect into the other? I'd have made this 122B(M). If you felt that there could be a need to join a 100m passenger train with another 100m passenger train then could have provided a PL as well and thus 122A(C.) and 122B(C.) but I can't see anything in the specificarion that even hints at this, so best omitted; if however you feel that there is some hint that such a facility might be needed then provide and put a justifying note why you have decided that.

120A(M) OK

120B(M) Interesting that you have now assumed that all these points are 75km/h and thus provided MAY-FA. I agree but you have been inconsistent with yourself earlier.
Note that it is not permissible for a signal to show both a flashing yellow for one divergence and a double flashing yellow for another divergence, but it is acceptable (but relatively unusual) for a junction signal to display a flashing aspect for another divergence, so your layout is indeed OK.

118A(M), 118B(M) both OK
The 3 aspect head and SARI are fine since trains strating from rest. Well done for reading notes and providing this signal as requested.

116A(M) OK

116B(S) OK but I am not actually convinced that need LOS 302; however it is perfectly correct and 113 has been made a controlled signal so it is only a matter whether there is operational justification for it as well as GPL 301.

116C(S) OK

114A(M), 114B(S), 114C(S) all OK, similar comments as previous signals

301A(S), 301B(S) both OK but the MARI are not necessary; indeed you have not actually provided any on the plan and I think that is correct for this scenario


303A(S), 303B(S) both OK, but again I'd not have provided any route indicators. Had the freight been running in the down direction from the siding rather than just puling forward to be run around, then a main aspect would have been appropriate, but for this scenario I agree with your choice

305. Don't think we need the sugnal at all; it isn't actually wrong, just not required and therefore superfluous. If you have it then 121A(M) would need to pre-set it as indeed you have shown in that route box.

Typically all GPLs would be last wheel replaced; in terms of route boxes don't need to write the track conditions, just L in a circle and define that symbol as "last wheel replacement"

Basically the operation of a turnback siding is that passengers de-trained at C then train draws forward using a PL aspect into siding. Driver shuts down front cab, walks therough multiple unit to open up the other cab and waits there until time to return to platform.

306A(S) OK. You were correct to provide this GPL so that a train terminating in this platform can then access turnback siding.

===================================================================
I have a nightshift to do tonight ("3rd time lucky" we hope for Twyford which seems to be jinxed); hope I will have time to give further comments on the layout tomorrow pm

(18-09-2010, 05:17 PM)PJW Wrote: I have a nightshift to do tonight ("3rd time lucky" we hope for Twyford which seems to be jinxed); hope I will have time to give further comments on the layout tomorrow pm

Since it seemed to go alright (touch wood that I won't regret these words when in future get another >

Hello PJW,

Thank you very much for your very elaborate comments on my attempt.

I have taken note of your comments and have incorporated them into my 2007 attempt which I just posted this evening. If I have repeated some of those points that you raised my sincere apologies.

The salient points I wish to raise are:

Reversal of the Freight train at Down Slow at Platform C. I note your comment about the freight train being routed into the Down Siding and after loading/unloading to draw forward to the Down Slow at Platform C. I did not think about that as a possibility. However what was obvious was that the Turnback Siding was more than 400 metres long and a Frieght train was routed there to await its path it would be out of the way of the UP or Down Main.

The consideration for shunt signal 305 were as follows:

a) Signal 121 in its position 25 metres from the platform would result in the 400m Freight Train standing over points 206A and possibly 205A. While I did contemplate, shifting signal 121 forward to point 208A, I thought that its new position which is about 130 metres further away and given the curvature of the track would render signal 121 not visible for a train stopping at platform C. I did consider putting a banner at the platform but decided against it for reasons I cannot now recall.

Actually both Junction D and Station C are supposed to be MAY-FA but what would be a flashing yellow for one may require a flashing double yellow for another. How do I show this on the layout without giving the impression that I did in this attempt ?

The LOS 302 is to stop the engine after crossing points 201 so that it can now return to couple with the rest of the Freight train and propel it into the Turnback Siding.

3 letter track circuit identities

(22-09-2010, 05:36 PM)alexgoei Wrote: Hello PJW,

I have taken note of your comments and have incorporated them into my 2007 attempt which I just posted this evening.

Have just printed this off after a long day at work that became necessary at short notice; however I have a day off tomorrow and will look at then as I know exams are now very close!

Quote:The salient points I wish to raise are:

Reversal of the Freight train at Down Slow at Platform C. I note your comment about the freight train being routed into the Down Siding and after loading/unloading to draw forward to the Down Slow at Platform C. I did not think about that as a possibility. However what was obvious was that the Turnback Siding was more than 400 metres long and a Frieght train was routed there to await its path it would be out of the way of the UP or Down Main.

You are right that the freight would fit in the turnback siding and could be routed in there. The thing is however that unless it needs to access the siding, there is otherwise no rationale for it to need to reverse at the station at all.
I really think that the examiners worded the notes badly; I expect that they really anticipated all freight passing through, albeit needing to be held just beyond the station until a suitable time for a path on the double track portion. Where there is a siding with no declared traffic you still need to provide a route in and route out with just a little thought for its use, but generally safe to assume that use is rare so don't spend too long on it as it won't be important.

Quote:The consideration for shunt signal 305 were as follows:
Signal 121 in its position 25 metres from the platform would result in the 400m Freight Train standing over points 206A and possibly 205A. While I did contemplate shifting signal 121 forward to point 208A, I thought that its new position (about 130 metres further away), given the curvature of the track, would render signal 121 not visible for a train stopping at platform C. I did consider putting a banner at the platform but decided against it for reasons I cannot now recall.

I now see what you were thinking- a lot of it is valid and your solution would certainly work athough it isn't particularly desireable I think.
In reality we only have one freight per hour so it should always be possible to clear 121 for the freight to have a running move up to 129 to be held there for a path. We don't really want to waste one of the platforms holding a stationary freight, although I agree that permitting the use of the crossover 205 would be invaluable in those circumstances should that be the case.
So you are certainly not wrong- it is only that my judgement is that we don't need to worry too much about the problem on this layout scenario as I assess the likelihood of holding a freight at 121 to be low. It was however a very valid consideration; if you had drawn a line back from 305 along the track showing the 400m standage, then it would have given the clue to the examiner what you had been thinking.

The disadvantage of moving 121 to 208 would hae been that a freight train held at 129 would almost certainly have tailed back into its overlap and thus have prevented a train coming into the station to terminate / reverse; I suppose that you could have provided a ROL to overcome. Moving 121 would mean that 125 should move as well. I am sure you made the right decison to place where you did.
Just be aware that you do NOT need a signal at the end of the platform to tell the train driver to stop; they know to stop at the station and will do so (well except for the very occasional embarassing mistake) even if the signal is at green. Where the station is on plain line and no opposing moves then there frequently is no signal in the vicinity at all, but if there is a stopping hadway requirement to worry about then it improves headway if there is a platform starter.
In the case of station C there is certainly a lot of sense in being able to see the signal from the platform - it would be particularly essential if 122 had been provided with a PL aspect permitting permissive movements in the opposite direction onto a train that is assumed stationary- certainly don't want that train to re-start once having stopped and without a signal to prevent it then that might happen!

However don't assume that the visibility around that S bend kink in the track is really as bad as it might appear- the plans are not to scale vertically and really all that represents is a more gradual widening of the space between the Up and Down Slow to be say 5m apart - the reverse curves probably no worse than would occur when passing through a ladder crossover. You are probably thinking "Metro" where those curves may be very sharp and the line may be in tunnel that would certainly cut off visibility around the curve whereas in the open it isn't normally a problem (though if there are OHLE stanchions, vertical cutting etc then the same considerations apply. In the exam a sustained curve can be assumed to limit visibility but I don't read this examle as being too much of an issue here.

Quote:Actually both Junction D and Station C are supposed to be MAY-FA but what would be a flashing yellow for one may require a flashing double yellow for another. How do I show this on the layout without giving the impression that I did in this attempt ?

Your layout was fine in the Up direction as there was no signal that showed a flashing yellow for one divergence and a flashing double yellow for another; the junctions were as close as they could be but it was enough separation to be ok.
I was suggesting that MAY-FA for the transition Down Slow to Down Fast could also have been provided.

Quote:The LOS 302 is to stop the engine after crossing points 201 so that it can now return to couple with the rest of the Freight train and propel it into the Turnback Siding.

Whereas in older signalling we might have provided such signals, nowadays we don't. The driver is assumed to know what moves are to be made and where there is any doubt (e.g. not a scheduled regular movement) then the signaller ensures that comes to a clear understanding before commencing the sequence of moves. Provision of the signal isn't actually wrong, but we don't do it and would be regarded as excessive by the examiners unless you wrote a specific justification for its provision.

[quote]
3 letter track circuit identities

Hello, PJW,

I have also practiced on this year's paper in one and half hour, simulating the real exam. I contracted my work with Alex's, looking like similar.

He did much better than me, I just draw out the basic layout. I compared mine with his detailedly, and found I did not consider everything well, such as the freight reversing. But truely I still felt a little happy, because contrasting with my former work, I found I had learnt much during these months. Thanks for your help and all the people here.

But what I am worried now is from my work, what do you suggest me to read in this week as not too much time left? I do not need your detailed comments as I know you are busy these days. I just want to what are the key errors in my work and which knowledge should I read carefully before the exam. I know I can not improve very fast only in few days, but just want to try my best to prepare in the limit time. Thanks a lot.