(02-09-2014, 03:57 AM)greatnessjason Wrote: Hi PJW,
Thanks for your comments. I agree could make a mention of signal sighting re cab sight lines, but I would think this statement would not be specifically addressing any part of the question - it could be a statement that affirms the examiner that I actually do understand the issue? In the exam scenario do you think any marks would be given for making such a statement?
For your convenience I attach the question here:
A railway operates an urban and inter-urban rail service utilising lineside signals at speeds up
to 100MPH (160km/h). It is proposed to replace the current 144m long trains with trains of
184m length.
Identify three issues of infrastructure compatibility which need to be considered. [3 marks]
At stations, the stopping positions are going to be closer to the existing signals. The
administration is considering moving the signals or extending the platforms in the rear.
Describe the advantages, disadvantages and commercial implications of the two options.
[10 marks]
At two locations it is not possible to relocate the signal or extend the platform, requiring the
train to stop approximately 1.5m from the signal. Describe two possible solutions to enable the
train driver to be fully aware of the signal aspect taking account of modern multiple unit design
features such as restricted visibility. (Novel, practical solutions will achieve extra credit).
[12 marks]
Now I have looked at question and seen the marking scheme then I actually think that you went into too much detail for the first 3 marks.
You could have been more brief re item 1, item 2 about right and I suggest that for item 3 rather than list what the question is going on to tell you anyway then the traction power supply issue might have been a better one to mention.
Whenever looking at advantages and disadvantages of a pair of options, try not to waste time by saying that A has an advantage and then B has the equivalent disadvantage. Better to have a first column explaining the issue and then Advantage and then Disadvantage columns and enter in these option 1 or option 2 accordingly. So for example if need to reposition other signals for braking is being considered, then the disadvantages are for 2 and you can list them but just put 1 in the corresponding advantage column since it does not suffer these.
I think you should certainly have pointed out that if the stopping position is to be closer to existing signals then the likelihood of SPAD would be increased and therefore safety risk would be increased.
Similarly you haven't mentioned that if move signals then need to reconsider the train protection arrangements. Also if there are any raised sections of platform to ease wheelchair access, then if train stopping position altered these will no longer line up with the doors!
It does depend on the site of course, but actually the construction of extended platforms may often be less disruption to travelling public; different situation though if in tunnel etc!
The last part of the question had a large number of marks allocated to it, but don't think you'd have got many of them. You didn't seem to focus on means of the driver being aware of the signal aspect when stopped very close to it.
In fact I can't see what I'd write on this subject for so many; I think therefore I'd have avoided the question and chosen another. There is something about the last sentence that suggests the examiner is faced with this as a real life problem that they don't know how to solve and wants a candidate to suggest a possible solution for them!
PJW