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+---- Thread: 2011 Question 11. Aspect Sequence (/showthread.php?tid=1058)
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2011 Question 11. Aspect Sequence - Murugesan india - 30-07-2012
Dear Members,
I have solved and attached the aspect sequence chart for 2011 Module 3 question No 11 and also attached the Module 3 question paper.
Kindly have a look and give your valuable comments.
Kindly correct me if I’m wrong.
Note:
1.All the Down slow signals are placed with inadequate braking distance,
2.Consecutive double yellows & Approach Release from Red features are used,
3.I feel there is no use of providing ROL for the signal 111 and 113.
4.It is assumed that the rear signal of 105 and ahead signal of 117 are placed based on the braking distance.
Regards,
Murugesan
RE: Aspect Sequence Chart for the year 2011-question 11 - PJW - 02-08-2012
(30-07-2012, 03:27 PM)Murugesan india Wrote: Dear Members,
I have solved and attached the aspect sequence chart for 2011 Module 3 question No 11 and also attached the Module 3 question paper.
Kindly have a look and give your valuable comments.
Kindly correct me if I’m wrong.
Note:
1.All the Down slow signals are placed with inadequate braking distance,
2.Consecutive double yellows & Approach Release from Red features are used,
3.I feel there is no use of providing ROL for the signal 111 and 113.
4.It is assumed that the rear signal of 105 and ahead signal of 117 are placed based on the braking distance.
Regards,
Murugesan
I'll try to have a look at this soon, but at present there is an Olympics on, and "volunteering" wearing a magenta-pink tabbard. This is not the type of question easily answered in such circumstances.
However you are right that the essence of this question is all about signals which are spaced closer together than braking distance. Hence consequtive YY (and possibly a case of consecutive Y) as well as approach release will feature.
I interpret your notes as the assumptions you would have stated in your answer. I think the examiners arranged to have a ROL for a reason, and therefore if your answer is not going to include it I suspect that you would lose some marks. Certainly you should have given a bit more explanation of why you do not consider it valuable.
RE: Aspect Sequence Chart for the year 2011-question 11 - reuben - 20-08-2012
2011 Mod 3 Q11 asp seq diagram.pdf (Size: 74.18 KB / Downloads: 213)
2011 Mod 3 Q11 asp seq model answer commentary.pdf (Size: 40.36 KB / Downloads: 208)
Dear Murusegan
Sorry for my slow reply to your posting - Peter asked me to respond, but I was being stupid and have only just found the correct thread!
I have also posted my own "model answer" to this question, but please be aware that this is a suggested, not necessarily unique solution. I have tended to use more of consecutive YY and consecutive Y in my solution, but reading the standards you could equally apply MAR in many of the cases. The MAR solutions effectively require there to be a signal which has correct braking, which can be approach released from red to allow approach to the signal with substandard braking; however in this case, there is often not a "good" signal you can apply the MAR to in the first place!
Signal by Signal comments:
107 at red - correct
111 at red - the distance from 105 at YY to 111 at R is underbraked.
111 at red (ROL) - correct
113 at red - MAR on 111 has been correctly applied to resolve the underbraking (unfortunately 111 is underbraked already, but you can't lose marks for this twice!)
113 at red (ROL) - the examiners will give extra credit for distinguising the different time delays on AAG occupation for the full OL and ROL approaches; in particular, the two appear identical on your answer.
115 at red - it would be better to use the G-YY-Y-Y-R sequence rather than G-YY-YY-Y-R, because of the rule that the distance from first Y to R should be at least one third of the YY-R distance.
117 at red - correct in itself. however, your choice of MAR on 115 now means that there is no use for the YY aspect in 113, so 113 should be 3 aspect - see how the G and YY aspect lines in 113 are joined at both sides.
119(?) at red - correct
junction aspects in 113 - correctly shown. However the line for approach release of 113 from Red is attached wrongly to its Yellow aspect line (a very common error)
Down fast line sequence - all correct, including banner (not named)
In summary, this response has grasped the subtleties of the question, and so is likely to score well in the exam. the opportunity to show that you know the difference between the G-YY-Y-Y-R sequence and G-YY-YY-Y-R
sequences has been missed.
Reuben
RE: Aspect Sequence Chart for the year 2011-question 11 - Murugesan india - 22-08-2012
Dear PJW/Reuban,
Thankyou verymuch for your valuable comments, i will improve it.
Regards,
Murugesan
RE: Aspect Sequence Chart for the year 2011-question 11 - PJW - 25-08-2012
(22-08-2012, 01:47 PM)Murugesan india Wrote: Dear PJW/Reuban,
Thankyou very much for your valuable comments, i will improve it.
Regards,
Murugesan
Some further thoughts of what the examiners might have been looking for on this very UK specific detailed question:
1. Some other assumptions that could have been made
- sighting of 113 signal and JI to allow release as soon as train has passed 111.
- non standard sequences (as opposed to MAR) are necessary for headway purposes
- risk associated with non standard sequences is acceptable
2. Ideally the distances of the signals 'off plan' would be quoted (at least the minimum distance and preferably the assumed actual distance - important to ensure both sufficient distance and no 2/3 - 1/3 breach, noting 1/3 of minimum is now acceptable)
3. The MAR - 111 ROL is probably there to allow a train to get closer to the station whilst there is another train stationary in the platform. Similarly 113 ROL would allow a train to enter the station with a train stood at or passing 115. These are provided and you should show them on the aspect sequence chart if you don't want to risk loosing some marks.
4. The reason for the close spacing is likely to be to achieve good headways on a suburban line so the ROLs would assist with this. This also supports Ruben's choice of approach (i.e. YY-YY etc rather than MAR)
We learnt at the exam review meeting that lots of candidates in last year's paper either didn't spot the underbraking or simply ignored it. There is a lesson here - if a question looks too simple it probably is! Always worth thinking how you can get 25 marks for a question, if you can only see 10, you are probably missing something and best to avoid that question.....
RE: Aspect Sequence Chart for the year 2011-question 11 - asrisaku - 04-08-2014
Another attempt, and try best to practice
Best regards, Arnut
RE: 2011 Question 11. Aspect Sequence - PJW - 19-08-2014
(04-08-2014, 06:23 AM)asrisaku Wrote: Another attempt, and try best to practice
Best regards, Arnut
Please see attached comments- sorry it has taken so long for me to find the time.
Note that the UK mainline does not ever use the sequence G-YY-Y-Y-R.
However consecutive double yellows G-YY-YY-Y-R is used (but only where we really have to).
I do like your idea of colouring the question paper to get a clearer view of how distances compare to braking distance and the form of sequence to be used; do remember however that your answer paper will be photocopied in black and white before being sent to examiners and you are told not to use colour differentiation in your answer.
There is a comment from you I cannot really read- I think it asks whether to show a swinging overlap on an aspect sequence chart- NO. The Control Tables etc give details of swinging overlap controls but for consideration of SEQUENCE then this is irrelevant. A Red will a full overlap is a Red with a full overlap and the diagram is to show the warning given to the driver at previous signal(s).
A Red with a ROL is different because the risk associated with a SPAD is greater and this is mitigated against by making the signal in rear more severely approach releases and therefore this IS significant for an aspect sequence chart.
I have made more detailed comments on the 2nd file, marking the cummulative distance as I worked back from each Red to check the attempted solution and amending the diagram where I feel it needed correction.
Do also have a look back up this thread where Reuben has provided what he believes is the model solution together with a commentary on that.
RE: 2011 Question 11. Aspect Sequence - asrisaku - 21-08-2014
Thanks PJW and I understand well for long process. I have just printed all out to study with the comments given.
Thanks for info that the answer will be scanned only black and white. I thought that I am going to highlight that on the exam day. Accordingly I'll just go only black and white and will not implement highlight to save time.
Regarding O/L, I thought that it might be better to show the examiner that I aware of diverging overlaps. However, as you said, I'll not provide them.
At the first time considering the question without looking at the model answer, the answer from my attempt was stuck and I tried to handle with all underbraking distance with MAR and then was surprised with non-standard 4-aspect later after looking the model answer.
Note: This is one of the tough questions for me as I experienced for aspect sequence questions.
Best regards
Arnut
RE: 2011 Question 11. Aspect Sequence - asrisaku - 21-08-2014
If I don't miss anything, everything at my attempt is fine.
Except:
1. Provide the signals off the layout to give the clear view for aspect sequence.
2. MAR needs only berth TC and other TCs with the length of PLJI 800m without delay time. Warning requires Berth TC with delay time.
3. Avoid the non-standard pattern G-YY-Y-Y-R. G-YY-YY-Y-R is ok to use in this case.
Am I right?
thanks again for massive help.
RE: 2011 Question 11. Aspect Sequence - PJW - 21-08-2014
(21-08-2014, 06:42 PM)asrisaku Wrote: If I don't miss anything, everything at my attempt is fine.
Except:
1. Provide the signals off the layout to give the clear view for aspect sequence.
2. MAR needs only berth TC and other TCs with the length of PLJI 800m without delay time. Warning requires Berth TC with delay time.
3. Avoid the non-standard pattern G-YY-Y-Y-R. G-YY-YY-Y-R is ok to use in this case.
Am I right?
thanks again for massive help.
1. Certainly for a layout like this where signals are spaced unevenly it is important to state your assumptions for outside the area depicted.
2. MAR requires the PJJI to be readable no later than the main aspect. The absolute maximum sighting is 800m, but depending on geography may be less than that. A sensible assumption for exam purposes is 400m.
Warning typically to release at 100m from signal. Hence unless there is some obvious hint that the berth track section is very short then it should have a time value- it depends on length but 20 sec would be reasonably typical.
3. G-YY-YY-Y-R is permissible, but is rare but in this case looks to be the best solution.