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2009 Main Line Layout
#1
Following the study weekend (thanks to all who came, hope you enjoyed it), i have posted my suggested solution for the 2009 main line layout. This was done failry hurriedly, but not in full exam conditions, and so represents something in excess of what you could reasonably hope to acheive in the exam itself.

The file posted has been slightly improved over the version handed out at the weekend: i have corrected the significant howler of forgetting to provide a means for the reversing goods trains to set out again!


Attached Files
.pdf   2009 Module 2 full solution.pdf (Size: 614.03 KB / Downloads: 527)
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#2
But we still do not know how to put all the equipments in the diagram, eg. where and which type of equipment can be chosen. Can you share us your explaination about the detailed method for this? And I never seen anyone share documents about this in this forum, all existing files are calculation...
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#3
(12-05-2010, 08:23 AM)greensky52 Wrote: But we still do not know how to put all the equipments in the diagram, eg. where and which type of equipment can be chosen. Can you share us your explaination about the detailed method for this? And I never seen anyone share documents about this in this forum, all existing files are calculation...

Do you have access to the Module 2 Study Pack?
It should be made available to students when registering for exam but it seems that the Study DVD for 2010 is not yet issued- I can probably get you the 2009 version by some means if that would help.

One reason why we haven't got much discussion of the basic rationale on this website is that there is a very comprensive description together with worked examples in that document. However there are in fact certn posts, such as this one discussing 2004

You are right that few people have submitted their layouts- it is a bit more difficult to achieve this due to the physical size of the paper and scans. However there has been some discussion about various portions of particular past papers such as for 2007 ; I suspect that you are after more basic information to allow you to get started rather than yet being able to discuss the nuances of particular layout solutions.
PJW
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#4
I agree entirely with Peter's comments.

If you've not yet studied the basics of the process for signalling a layout, then looking at a completed solution will not help very much! You're better not looking at this solution until you have studied sufficiently to be able to have an attempt at doing this layout, and then use this model answer to compare with yours.

Pending getting the study pack, here's a quick summary of the key steps, borrowed from my "signalling the layout" course!

This process does assume that you are already familiar with the basic items of equipment which you are placing at each stage. There's nothing wrong with you adopting this process for the signalling equipment and principles relevant to your home railway network - you don't have to pretent to live in Network Rail Land!

1. Perform headway calculations for the main line line of relevance in the specification, to determine the type of signals and what range of spacings they may be at.

2. Draft the positions of main signals, starting at fixed points such as junctions, and working away from these, placing signals at acceptable spacings. Try to position signals at overlap distance from pointwork, and with train standage on the approach. Often in the exam, features such as stations or junctions are positioned at regular spacings, which will guide you towards an expected solution. These features may also force you to provide a type of signalling which is more intensive than the bare headway calculation indicated.

2a. for other lines with unspecified headway requirements, judge a suitable type of signalling and then apply it in a similar manner.

3. Mark the limits of main signal overlaps.

4. When you
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#5
I have been practising attempting past papers and have the following questions arising from attempting the 2009 Main Line layout:

1.Using distance from G to R calculations at service speed of 120km/h; I determined that 3 aspect at 140km/h permissible speed would be suitable.However,on signalling the layout;I noticed tight spacing generally.Especially between Station B and Junction D and out of the tunnel to the junction after the single line along the down branch.When I tried 4 aspect;the spacings seemed to suit all the layout generally well.Is there a way my calculations could have forewarned me as I would have run into into serious time constraints in the actual exam having started using 3 aspect?

2.For the run around move between F and G;considering the distance, is it ok to signal using shunt moves on the Up Goods considering the distance?

3.Is it ok to signal the line from Station C to Station B using 3 aspect in the C to B direction with a stop and distant signal before the fixed diamond junction and permanent stop signal train length beyond platform for terminating trains.From B to C;use the platform 4 aspect starter to signal all the way to the buffer stop at B.Assuming axle counters for track sections.
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#6
Glad that someone is getting stuck into study for the exams; October isn't really that far away- only 5 months to go- and all these Bank Holidays could be useful for that work if you can resist the temptation of spending them more enjoyably.

I haven't actually done this paper myself so just looking at it "cold" on screen to make my comments-

1. You haven't attached your calculations which would have made it easier to comment. However compare the MINIMUM spacing [due to braking requirement] with the MAXIMUM spacing [the more onerous of the two constraints: a) re overbraking, b) headway requirement] and see what tolerance there is between the two extremes. If there isn't much, then that is telling you that although 3 aspects would in theory be a solution, as soon as other constraints such as junction positions, stations etc are taken into account then in reality it'd be too tight to be able to juggle to give a workable solution.
Note that even in circumstances where the headway is easily achieved given signal spacing for braking, there are other constraints. Personally I advise people not to launch straight into the calculations for this very reason; THINK ABOUT THE SIGNALLING AT CRITICAL PLACES FIRST. In fact you can even do something of this in your 10 minutes reading time, looking at where the constraints on the layout are; afterall the IRSE tend to use the same braking rate each year and there are only a few speeds so having done lots of previous papers you should know pretty much what the braking distance from the relevat speed will be; learn what it is at say 100km/h and that would at least give you a yardstick from which to do a first assessment.

The Distance "Green to Red" method has its uses but does tend to make the consideration purely numeric and doesn't help intuitive understanding. However if you do use it and find that N is only just greater than 2 (i.e. there is only just enough for two signal spacings within the headway distance), then that is telling you that it is tight!

2. I am assuming you are meaning that a train from F towards G (or from G towards F) will be temporarily left in the Up Goods for loco to detach and run around via the Up Main.
I guess that there would be a main signal route from the Up Goods to the Up Main provided as a running move anyway, so the light loco would utilise this. Then certainly a set-back GPL at the trailing end of the crossover would be ok (though if the layout had been slightly different and a main signal for a down direction departure had been needed for that platform at station B then obviously would have been combined with that).
A further GPL would protect trailing crossover at D to signal to a the Up Branch- initially I was thinking of an LOS but actually would be to a signal ainstead (as this line has to be bi-directionally signalled to be able to signal the complete train that way later on!)
Provide a PL associated with the signal on the Up Branch which authorise movement into the loop.
Provide a main signal for departure in the down direction from the loop for the whole train.

However given that there are 6 trains each way, then they'll be 12 runrounds. We need to make (and state!) some assumptions about when these freights run (mainly at night when there are few if any passenger trains but perhaps two runrounds to take place per hour, or very much amongst them in which case it seems as if this runround is hapenning hourly. So whereas signalling above is ok, as you mention it is quite a long way to run just on a PL.

Whereas I feel acceptable from a driver's perspective, I would wish also to consider the effect on line capacityof the move taking place only at say 10mph. If this proved too much of a constraint then providing a main aspect at the right hand end of the platform at B would help; note that this would require a main signal (i.e. fixed red with associated PL aspect) protecting the crossover at D. In fact it may then be sensible to make this a full signal given that the next one has to be a main signal; that would then give an option for a passenger train to reverse at B at not uch more additional cost. If that is the way in which your thought process goes then YOU MUST EXPLAIN since it will look oversignalled by providing a facility not required by the operating specification.
So if you decide that the runround has to be done by main aspects to avoid impacting upon layouts capacity then show where this comes from and then point out that the differental cost of a R/Y/G compared to a R+PL is pretty marginal (indeed from a signal structural viewpoint the former is likely to be cheaper!). In the real world a contractor would raise a "Technical Query" to the client and by stating assumptions to the examiner you reflect this in exam conditions. Of course for that facility to be really useful it'd also need to be possible for the return working; this would need a further junction indicator and route across the trailing crossover at D, so I would not show these but place a note against signal profile and route box "subject to agreement by client"- these "nice-to-haves" all add cost and complexity and so add up even if each individually is "marginal"......

3. Not quite sure what you are meaning; as I think you know "stop and distant" is still 3 aspect signalling (albeit "isolated 3 aspect signalling), even though each of the signals are only 2 aspect signals.
However I think the answer to your question is "nearly but not quite right"

Certainly there is only one train at any time on the branch doing an out-and-back; given the layout at B it would seem to need to be the same actual train going back onto the branch, rather than "one off and onother on". Hence need minimum number of signals.
Since you have decided to utilise Track Circuit Block (albeit with axle counters), yes you need a signal as a platform starter at C and yes it would be a Red/Green (I think, but see later).
You'd need another signal protecting the diamond which would be a Red/ Yellow and a further one at or beyond the lefthand end of the platform at B which as you say would be a fixed Red.
There would need to be a distant approaching the signal protecting B- this could be provided as a reflectorised distant board. Work out where it would be placed and if it is actually pretty close to C then perhaps reconsider what I said above and make that a 3 aspect signal instead of providing that distant board.
I think the above reflects what you were intending, but not 100% sure from your description.

In the opposite direction, yes the 4 aspect signal would have a route onto the branch, but it would only be capable of showing Green for that direction.
There would however also need to be a reflectorised distant board, braking distance from C; a yellow at the B platform starter would be vastly overbraked and forgotten about by the time the train approaching C.
Also don't forget the bufferstop light at C
Further you ought to make some reference to TPWS for this bufferstop and indeed for your fixed red at B; I hope that you'd be writing some general note re provision of AWS / TPWS applicable to your layout rather than drawing them each time, but you ought to make sure that you amended that wording to incorporate these special cases or draw in explicitly



See also
the relevant post in Attempted Layouts
section

(22-04-2011, 09:40 PM)Sid G Wrote: I have been practising attempting past papers and have the following questions arising from attempting the 2009 Main Line layout:

1.Is there a way my calculations could have forewarned me as I would have run into into serious time constraints in the actual exam having started using 3 aspect?

2.For the run around move between F and G;considering the distance, is it ok to signal using shunt moves on the Up Goods considering the distance?

3.Is it ok to signal the line from Station C to Station B using 3 aspect in the C to B direction with a stop and distant signal before the fixed diamond junction and permanent stop signal train length beyond platform for terminating trains.From B to C;use the platform 4 aspect starter to signal all the way to the buffer stop at B.Assuming axle counters for track sections.

PJW
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#7
(22-04-2011, 09:40 PM)Sid G Wrote: I have been practising attempting past papers and have the following questions arising from attempting the 2009 Main Line layout:

1.Using distance from G to R calculations at service speed of 120km/h; I determined that 3 aspect at 140km/h permissible speed would be suitable.However,on signalling the layout;I noticed tight spacing generally.Especially between Station B and Junction D and out of the tunnel to the junction after the single line along the down branch.When I tried 4 aspect;the spacings seemed to suit all the layout generally well.Is there a way my calculations could have forewarned me as I would have run into into serious time constraints in the actual exam having started using 3 aspect?

I have not got the layout with me at the moment, but from what you have said, I suspect you are overlooking something - just because 3 aspect will meet the headway requirements, this does not mean that you would not use some four aspect signalling where the need arises. If the spacing constraints in the station area make this inevitable, use four aspect in this area and sort out the transition to and from the 3 aspect signalling that meets the requirements on the open line.

I'll try to get to look at the other questions when I get a chance to look at the layout.

Peter
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#8
(22-04-2011, 11:03 PM)Peter Wrote:
(22-04-2011, 09:40 PM)Sid G Wrote: I have been practising attempting past papers and have the following questions arising from attempting the 2009 Main Line layout:

1.Using distance from G to R calculations at service speed of 120km/h; I determined that 3 aspect at 140km/h permissible speed would be suitable.However,on signalling the layout;I noticed tight spacing generally.Especially between Station B and Junction D and out of the tunnel to the junction after the single line along the down branch.When I tried 4 aspect;the spacings seemed to suit all the layout generally well.Is there a way my calculations could have forewarned me as I would have run into into serious time constraints in the actual exam having started using 3 aspect?

I have not got the layout with me at the moment, but from what you have said, I suspect you are overlooking something - just because 3 aspect will meet the headway requirements, this does not mean that you would not use some four aspect signalling where the need arises. If the spacing constraints in the station area make this inevitable, use four aspect in this area and sort out the transition to and from the 3 aspect signalling that meets the requirements on the open line.

I'll try to get to look at the other questions when I get a chance to look at the layout.

Peter

Thank you Peter.

I will await your further answers after you look at the layout.

It does seem though that using 4 aspect fits snugly with the layout and; unless I am not doing something right would use less time than figuring out the transitions from 3 to 4 aspect into station areas.

I would also be grateful if you could also give general advise on how best to signal the tricky areas of that layout for my benefit after you have had a look at it.

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#9
1) 4-asp is the most obvious answer but there are better options which would reduce the 'cost' by minimising the number of signals but that requires some complex understanding of aspect sequences.

2) Yes it is okay to use shunt moves but why not use main aspects? Less restrictions on speed and would clear the mains faster.

3) 2-asp is more than ample and simple to implement. You may want to consider the 'one train in steam' principle of operation. No track circuits then except on the exit berth signal.

Jerry
Le coureur
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#10
(22-04-2011, 09:40 PM)Sid G Wrote: I have been practising attempting past papers and have the following questions arising from attempting the 2009 Main Line layout:

1.Using distance from G to R calculations at service speed of 120km/h; I determined that 3 aspect at 140km/h permissible speed would be suitable.However,on signalling the layout;I noticed tight spacing generally.Especially between Station B and Junction D and out of the tunnel to the junction after the single line along the down branch.When I tried 4 aspect;the spacings seemed to suit all the layout generally well.Is there a way my calculations could have forewarned me as I would have run into into serious time constraints in the actual exam having started using 3 aspect?

2.For the run around move between F and G;considering the distance, is it ok to signal using shunt moves on the Up Goods considering the distance?

3.Is it ok to signal the line from Station C to Station B using 3 aspect in the C to B direction with a stop and distant signal before the fixed diamond junction and permanent stop signal train length beyond platform for terminating trains.From B to C;use the platform 4 aspect starter to signal all the way to the buffer stop at B.Assuming axle counters for track sections.


Thanks PJW and Jerry.Your replies have cleared most of my grey areas about how to signal this layout.
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