I am a little surprised by some of what you wrote for the first portion.
a) I would assume that a particular aspect display would have equated to a single speed value, or at most perhaps a current speed and a target speed to achieve by the next signal. "Speed profile" sounds an odd term to use as to me it implies a whole range of separate distances and associated speeds.
b) You do not explain why it relies heavily on the driver's knowledge of the railway; in Europe it is typically held that the use of speed signalling minimises the need for specific route knowledge.
c) Whereas I appreciate that a signalling system can well have elements of speed signalling and route signalling, I feel that mentioning route indicators and junction indicators here rather confuses the issue. I think that you should initially have restricted your description to an ABSTRACT signalling system and thus been able to consider the issue theoretically and kept things pure, before muddying in such a way. Hence better to have added at the end as a codicil.
d) I think that your item 5 was the heart of the matter and that rather than items 1-4 then you'd have done better to explain a little more. I do not know Victoria signalling practice but find that having read, I still don't know much more than I did before. I am guessing that the A, B , C can each display Red, Yellow or Green and that you are telling me that a Green in the C means a slower speed than a Green in the A, but I have no idea if the other units would necessarily be showing red at this time or whether aspects such as triple yellow are permitted. Similarly I do not know if a Yellow instead of any particular Green means a lower speed at this particular signal or actually means a need to brake so that have reduced speed by the time of the next signal to a different value.
It would have been better to have made a grid and marked up combinations of A/B/C colours and given their meaning to the driver in terms of speed- if there are very many combinations just some typicals could suffice.
In portion 2 you have wasted a few valuable seconds by starting each sentence by "Information regarding the"; you could have eliminated these words x5!
I also take issue with some on your list- for example driver does not fundamentally need to know the aspect of the signal ahead as that itself is only itself a means of conveying further information.
When the question says "any signalling system", I believe this does NOT mean "choose any specific system" but means "common to any form of signalling system".
Hence I think it should be more like-
a) current permitted speed,
b) forthcoming speed restriction (be it a permanent speed restriction due to geography etc or as a result of a need to stop because of another train),
c) where to stop,
d) category of route (so that does not attempt to take a passenger train into sidings),
e) characteristics of a route (so does not attempt to take an electric train onto an unelectrifed line or a diesel locomotive into a tunnel with inadequate ventilation etc)
f) gauge of a route (could be the rail width separation if from a dual gauge line, but also structure gauge and indeed even weight limitation) to be able to ensure compatibility between rolling stock of train and the route clearance.
However I do think that your item 5 was also worth including.
When you came to portion 3 and considering Distance To Go type signalling the fact that most of your entries were "not provided" is really a hint that you hadn't actually got the right items on your list.
It may have been better to have used a tabular type presentation on A3 blank answer paper with the three fundamental types of system depicted in a separate column.
Given your portion 2, you made a reasonable stab at the last portion. However I think you should have considered the type of information that is not readily available to the driver in each of the types and thought about if this could lead to errors. Your answer did not include any signaller errors but the question explicitly asked for these and moreover was actually asking HOW POTENTIAL ERRORS ARE MANAGED and you didn't really address that.
For example on a distance to go in-cab display, if a passenger train had been incorrectly signalled into a maintenance depot, the driver might simply drive their train full of passengers in accordance with the distance to go and speed info. This could be managed by the display giving a text statement or additional icon to supplement the information and perhaps give an audible alarm and require the driver to acknowledge it.
In route signalling, there a chance that the driver will fail to see or appreciate the significance of the route indicator and drive to a speed appropriate to the main aspect colour. This can be managed to some extent by ensuring that the route indicator becomes readable no later than the main aspect and taking into account complex signals take longer for the driver to assimilate and thus ensure that an extended minimum reading distance is provided.
In speed signalling there is a chance that a driver may get confused what speed a particular combination of lights actually reflects. [I think there was a particular issue when the railways of Sweden and Denmark were linked for the first time by the construction of a new bridge and the two similar but subtly different speed signalling systems became connected; the same combination of light colours meant something different on either side of the border!]. Potentially could be managed by a comprehensive train protection system to intervene should the driver make a mistake.
Overall I think this question should have been answered more reflecting the broad generic principles of the different philosophies. I think most real signalling systems do have a certain "blurring of the edges"- as you suggested some route indication can be useful for a fundamentally speed signalling system and some speed signalling features can get incorporated into a route signalling system. I think it is important to recognise that a "signalling system" refers to more than just the signals; it can include lineside signage, operating rules, driver's route knowledge etc. You have perhaps hinted at some of this but should have made it more explicit.
I think that the overall length of your answer was reasonable; not too much content for the marks available. I do think that some of the content wasn't going to get you marks but it is more a question of replacing it with more valuable material rather than cutting the length of the answer.
(02-09-2014, 07:59 AM)greatnessjason Wrote: Different railway administrations utilise “distance to go”, “route based” or “speed” signalling,
sometimes in combination.
Briefly describe how one of the above styles is implemented. [7 marks]
Identify the information a driver requires from any signalling system in order to correctly
manage the train. [6 marks]
Describe how each style of signalling provides the required information to the driver including
the potential for errors by the signaller or driver to be managed.[12 marks]
I've attempted this question however took me quite a while to come up with the points, not sure whether this is just enough content for the marks available or is this too much?
