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2014 Layout Attempt
#1
Hi,

I've had an attempt at 2014 layout under exam conditions (also not pre looked at papper either).

Any feedback would be much appreciated.


Attached Files
.pdf   Calc.pdf (Size: 281.62 KB / Downloads: 183)
.pdf   Layout.pdf (Size: 1.36 MB / Downloads: 217)
.pdf   Paper.pdf (Size: 348.03 KB / Downloads: 105)
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#2
(24-09-2015, 03:10 PM)MikeMurphy Wrote: Hi,

I've had an attempt at 2014 layout under exam conditions (also not pre looked at papper either).

Any feedback would be much appreciated.

Sorry that I overlooked this post; there has been a sudden rush of posts on this website and other students contacting me separately; the reality is that I do have a day job and can't single-handedly deal with everyone's last minute attempts but would have dealt with this one sooner had I realised it was waiting since I tend to prioritise those who make their work publicly available on the basis that may be of wider benefit than just to that one person.

First thing is that I know little about Northern Ireland practice; from my brief visits I have noticed very little difference from the UK so I will be commenting based on this, but perhaps some comments re facing shunts, route indicators, overlaps etc. may not be quite right.

There are a range of things to point out here, some quite quick fixes but others which are likely to be too late I am afraid to be of a lot of benefit to you now.  Anyway to start with the things that would be losing you disproportionately number of marks for silly reasons but would actually be easy to correct your understanding and give a far better impression-

1. Trap points.  
  • You need to number them.  
  • You need to draw the normal lie to derail and "break" the already printed solid line, perhaps by using typex.
  • You need to draw the Track Circuit Interupter on the stock rail (i.e so it is broken if train about to derail)
2. GPLs
  • You need to draw them the correct way around- you seem always to have directed them in the Up direction if Down direction signals and vice versa!
3. End of track circuited area symbols
  • These are also almost always the wrong way around; the L shape should be such that the bottom horizontal line is directed INTO the area that does have track circuits
  • Where track circuiting commences "at" a signal then the symbol ought to be drawn JUST BEYOND the signal- not on the approach side but also not leaving a large gap between the signal and the commencement of track circuiting
4. Overlaps
  • If these are not the standard (I am assuming 180m) then they should be dimensioned; if under the standard length then justify (lower line speed etc.)
  • However do not just measure 180m beyond a signal and plonk them down; if this distance falls inappropriately in pointwork, then choose the next track joint and make the overlap that bit longer.
5. Route Indicators
  • Make sure that the route indicators provided are consistent with the associated route box (even if you don't have time to provide them for all signals, at least think through to ensure that they are correct for all the routes that should be provided from that signal),
  • Whereas the same route indicator may be provided for going into one of several sidings and thus APPEAR the same to the driver, there actually need to be separate routes within the signalling system for the signaller to set the various routes and throw the points accordingly.  The only time that this would not be the case would be if the signaller sets into a yard and the points defining the actual precise destination were just handpoints operated locally.
  • Signals 120/122 for example don't accord with the route box, signal 112 PLJIs and MI don't accord with my estimation (in the absence of a route box) of where the various routes read.
6. Signals at the limit of the plan
  • The various Not to Scale Areas (such as a "A" and "D") are for you to show a signal in each direction.  As per the first of the "Important Notes for Candidates" at the left hand portion of the layout, you must DIMENSION these- this means drawing an arrow that says how many metres these are on the approach / beyond the adjacent signal on the main part of the plan.  In isolated 2 aspect signalling, I would recommend drawing both the stop (R/G) and its distant (Y/G) for each direction.
  • It can be a good idea to treat these signals as being those of the adjacent signalbox and number them accordingly in a separate sequence such as A101 and A102 and D1 and D2.  
7. Method of Block Working
  • You also did not seem to react to the 2nd of those "Important Notes", so again throwing away marks.  
  • As a minimum state "Track Circuit Block on all running lines", but (depending on the layout) you will probably need to say a little more for some portions.  In the 2014 case there are permissive passenger moves at station E and in the Up Loop at C and a transition to handsignalling at Freight Terminal near B.  The limit of track circuiting on the Arrival Line ought to have been taken up very nearly to the gates across the track at which site there should have been a "STOP and Await Instructions" reflectorised notice board.  On the Departure Line, TCB would start at 201 signal with moves up to this being handsignalling under the control of the Freight Terminal operator (since this line is unidirectional this can be done without reference to the signaller).  Whereas the limit of TCs could be placed just beyond 201 this would require the signaller to be advised that there was a train ready to depart; it would have been better (as you seem to have drawn AD) for the tracl to extend say 100m on the approach side of 201 as a berth track for indication (and possibly and audible alert for the signaller)

We now come on to the various other things where you would have lost marks but perhaps are rather harder to learn in the time now available.  However if your attempt were amended only in as far as the things listed above, it would have given a far better impression and perhaps may have passed despite the various deficiencies that I list below.

A. Make sure you read the Operating Requirements
  • You did not provide a call-on move to allow trains to join in the loop at C
  • The signal with the PL for the call-on moves into terminal platform is some 1800m away- ridiculous!
  • You did not provide all the signalling needed at station C to allow maintenance vehicles to arrive and depart in any direction under signalling.  There should have been a PL at 607B to allow a setback move from the Down Loop.  There would also need to be routes up to this GPL from signals 112 (Up Main) and 204/5/6 (Up sidings).  Need to think how a train from the Up Branch would be routed into it; I think I'd provide a GPL at 610 points reading to the Down Main as well as the fan of Up Sidings.  I would also provide a GPL at 616A; I would also need this so that a train FROM the Down Siding could leave along the Down Main and then be routed to the Down Main / Down Loop.
  • I didn't really understand the plethora of signals that seem to have sprouted like mushrooms all around the throat of station E.  I am guessing that 207 is a LOS to which 211 (if turned around by 180 degrees!) is supposed to be reading so that would be ok.  Assuming that 209 is also 180 degrees wrongly orientated , it still seems to be positioned in the wrong place; it should probably be at the tips of 617A (actually this is the obvious site for a main signal giving Main and PL (call-on) aspects  into the platforms as well as PL (shunt) into that Down Siding).  Given this it does appear that your signalling would permit a vehicle to be routed into / out from that siding, reversing in the platforms as necessary.
  • Think about train length and in particular the standage needed at signals.  The freights are 400m long and the passengers 230m; signal 113 is only about 180m from the CM/CN track joint so if it is at danger even if the driver pulls right up to it (rather than stopping say 25m prior to it as is the normal standard) then even a passenger train will be blocking the Up Loop at least and may well still be locking points 611 Reverse and thus blocking the Up Main as well!  Similarly it would be sensible to be able to hold freight train on the Down Main whilst being able to route a passenger train around it via the platform Down Loop; also on the Up Main whilst the passenger goes via the Down platform loop.  Always think where the BACK of the train would be.
B. Signals protecting Junctions
  • You have placed no signals on the Up Main and Down Main (Up direction) in line with 109 & 110; may not actually be wrong but doesn't seem sensible (see also the previous and the next section re this)
  • You don't have a signal on the Down Main equivalent to 111 on the Down Loop; this must be wrong as at very least you need a signal which routes to the Down Branch so bad mistake
  • Another obvious omission is a signal at the end of the Up Branch protecting the junction at 610 points- bad mistake.
  • As stated above, signal 119 is far,far too far from station E platforms and the associated pointwork in the station throat.
  • 114 seems to have been given a flashing yellow aspect, yet the following signal 112 nly seems to feature routes that are MAR and all the pointwork I assume to be 40km/h.  I do agree that the note says "all other running line turnouts" which would suggest that some are faster, but none seem to be marked on the layout and the other text in thr notes does not define explicitly.  You could perhaps think that points 609 / 611 / 612 / 610 might be faster to permit a 100km/h speed from the Main onto the Branch and vice versa but since not explicit in the question then if this is your interpretation you should state obviously.  For MAY-FA to be applicable though it would need points 613 to be for fast running and I see nothing at all that might suggest that they are.

C. Signal Spacing

I have yet to look at your calculations, but this is very erratic to say the least!
  • Starting at 101, I can't tell the spacing to 105
  • From 105 to 107 looks to be around 1700m
  • From 107 to 111 looks to be around 1050m; without a signal parallel to 111 on the Down Main then that signal would be reading also to 115 that is a very long way away on the way to "D" and also to 113 (which is actually surprisingly close after the junction onto the Down Branch and for some unknown reason has been drawn as a 4 aspect.
  • If there had been a signal approx parallel to 111 then the distance to 115 would have been 1600m whereas to 113 only 600m.
  • 115 to the signal at "D" is unknown distance
  • 113 to 119 is some 1400m- does not seem a rational reason for the top yellow aspect
  • 119 to bufferstops is 1800m
  • 120/122 to 118 is 1800m (the trains must be starting from rest so the attainable speed is LOW!)
  • 118 to the missing signal for the next junction would be about 900m
  • 116 to 114 is unknown distance
  • 114 to 112 is 1300m
  • 112 to 110 is about 1150m, but without a parallel signal for the Up Main would be some 2250m to 106
  • 106 to 104 is 1650m
  • 104 to 102 at "A" is unknown distance
  • 109 seems to read all the way to 103 at the end of station B- I am not even bothering to estimate this length!
Therefore the impression given to the examiner is that signals have not been carefully spaced taking into account the various constraints of the geography of the layout, considerations of braking and overbraking and the headway requirement.   This is definitely an area of weakness; at this stage before the exam all you can hope to do is to recognise the worst elements of the above and seek to avoid in the exam.  

Calculations
Your calcs just seem to reflect the braking distances at the various speeds:
  • 1700m from 175 km/h
  • 1420m from 160km/h
  • 550m from 100km/h
which for 3 aspects defines the MINIMUM spacing.

There seems no consideration of any MAXIMUM spacing from either constraint:
a) consideration of the headway that ought to be achieved to be able to operate the defined level of traffic,
b) consideration of how widely spaced the signals could be without the distance between the Yellow and the Red becoming too excessive (driver should brake at the Yellow butif the signal spacing is very much more than the braking distance then they will then be crawling for a long length until they eventually get to the exit signal and therefore the whole purpose of putting a signal to give warning of the need to stop gets somewhat undermined)

The few lines of text on the 2nd sheet of the calcs doesn't convey much information or convince the examiner that you are displaying much understanding of the issues involved.

So whereas you did Question 1 part a), you didn't do part b)- despite having started your answer by defining the terms that you actually never subsequently used.

You made no attempt to get to terms with the detailed question re train running on the paper within part c); actually the hardest thing about this part was understanding what was being asked, since the calculations are relatively easy. Perhaps you made a conscious decision to omit on te basis that you would gain "more marks per minute" for  doing other parts of the paper- possibly that was the right decision for you.

The real crucial things are-
  • not to miss out critical signals protecting pointwork,
  • avoid stupidly long permissive passenger movements,
  • make sure that there is at least braking distance warning of approaching a red
  • at the end of your calculations decide upon the minimum and maximum spacing constraints you will use for spacing signals on your layout (or relevant separate portions thereof) and actually implement what you have stated

There are a few other odd things such as:
  • double allocated signal numbers (I do suggest leaving some spares n the numbering sequences just in case you find that you have missed a signal whilst doing the exam),  
  • some IBJs that look too close into convergences at points to be considered to be beyond the associated Clearance Point,
  • assuming that there are sliding bufferstops at the terminal platforms then the TCs in the platform should stop prior to them and there should be TCI beyond them to detect that they have been struck and displaced by a train hitting them,
  • a lack of track joints around the station E throat area which I assume is down to running out of time (I would recommend that you always put the obvious IBJs in for parallel moves and release of locking once clear of points etc. at the time of numbering the points so that even if don't have time to letter the tracks and get every joint in you at least put in the critical ones in before you forget and it'll cost you barely any extra time at all when in that mode)
but these are relatively minor.  You had a good level of completion and if you can avoid some of the basic things that would have had a significant detrimental effect on your score then I think that you would probably pass, but things like signals missing or facing the wrong way, inconsistent route indicators, failing to implement the instructions in the notes are the things that would sink your attempt.

Good luck for the weekend,
PJW
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#3
I have now managed to scan the comments that I have added to your layout attempt, which is best read in conjunction with the other textual response  and vice versa


Attached Files
.pdf   2014 layout, NIR stds, PJW comments.pdf (Size: 940.05 KB / Downloads: 145)
PJW
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