2009 Q9 Cab sight lines of new trains

[PJW]

Hi,
I have just attmepted question 9 in 2009 module 7 paper.
Please provide some feedback on it.
Thanks
Regards
Aditi

This is not a question that I feel particularly well qualified to answer but for what it's worth this is my opinion.
Perhaps a little short but otherwwise a good answer; certainly it was very clearly presented with, as requested by the question, the advantages/ disadvantages/ concerns for each of the 4 options. I think that I may have also have concluded with a very brief summary of the options, whether I felt any untenable or impracticable and notong the circumstances when to propose one or other solution at a site- just to round the question off.

You should have had a brief introduction re the environment you had in mind when answering your question- whether mainline, sub-surface metro or tube tunnels, since this could be highly pertinent to your consideration. Similarly note other assumptions that could explain your answer either initially or within the later text:
a) re where train operators stop for a signal- are there physical markers?
b) how the train length compares with platform length,
c) whether there is a crittical train detection joint just behind the last vehicle of the train when stopped at platform, how far beyond the station starter the replacement joint typically is?
d) whether the trains are fixed formation, whether trains join or divide or reverse direction in any platform etc etc.

There are some hints in your answer re these but you never explicitly state your assumptions; I am guessing that you may be describing the Sub Surface Lines of LU.

Part 1 was about the right length and content reasonable; irtcould perhaps have been more clearly explained and expressed. Certainly an initial exercise to eliminate those sites where it was clear there would be no problem before undertaking a more detailed site based activity to investigate thse where there may be a problem is sensible.

Option 1: To me the description of the option of moving the signal seems to imply it is to easy. Presumably it is today where it is for a reason and moving 3m may be quite difficult (does it place it into the tunnel, does it severely affect approach sighting?) and it may well necessitate move of track circuit joint and could in some cases be impracticable because of the need to protect crossover etc; the decommissioning of the existing signal seems quite a minor consideration by comparison. Hence I feel you underestimated the effort that would in general be incurred.

Option 2: I am unaware of the form that co-acting signals take on LU and the rules for applying them; I wonder if they may be more undertaking the role of a NR banner signal than what NR calls a co-actor...
They do have their uses on NR although we do try to avoid as much as we can for various reasons including complications re how to treat failure scenarios when the co-actor and main signal may not display the same. Presumably the "space envelope" on the Underground is such that co-actors are arranged to be viewed out of the cab side window, rather visible through the front window as on NR (i.e. just higher or lower or on the right but fundamentally at the same logitudinal position as the main head). I didn't quite understand your reference to side mirror- that is my problem for not knowing your environment but your answer could have helped me that little bit more. Similarly I didn't really follow quite why this was liable to be misread, though I could more easily understand it not being observed at all and thus a SPAD occurring. Again a little extra explaining WHY an extensive site-by-site approval would be needed could have helped- is there something more than a normal signal sighting procedure involved; if so presumably the solution is regarded as "risky" and it would help to better understand the rationale.

Option 3:
I can't see NR accepting this option, but perhaps in different environments it might be suitable. I think your comments were fair, but I must say that I'd be more concerned re the colour rendition rather than what I would assume to be a pretty minimal delay in updating the image.

Option 4:
Again I don't see this as a long-term viable option; your answer certainly implied this but didn't actually commit. Perhaps the place to have said so was in the additional summary that I mentioned earlier; option 4 perhaps would have its place as a short term expedient at a one-off site if there was a need to introduce the trains before the site changes had been implemented or perhaps as a temporary means of overcoming a failure of a coacting signal or the CCTV solution.

OVERALL
Hence I think your answer would rate a good pass but to get an even better mark you should have put just a little more flesh on the bones. I feel that you certainly LISTED pertinent advantages and disadvantages but in many cases didn't actually PROVIDE ANALYSIS. Where you wrote two lines per point I felt you had done so; some of your one-liners were enough but others could certainly have done with a bit more justification / rationale.

Hope that helps you a bit; feel free to come back at me.
I am sure that your answer will help others both technically re the subject matter and by giving an idea how to tackle a written question.

Obviously I am assuming that you quoted the question itself for convenience of those using the website; I am sure you wouldn't start a real exam answer by repeating the question!