2007 Q1 MARGINS & TOLERANCES IN CONTROL SYSTEMS

[PJW]

Sir,

I am enclosing my answer to this question. I have answered for the IRSE 2007 q1 Part 1 (i.e associated risks in the system during normal operation).

IRSE 2007 q1 Part 2: I have not enclosed. Since it is related to Part 1.

Please clarify whether my understanding and response are in the right direction. Please guide me if I need to expalin more about each risks.

Thank you.

Sincerely,
Jegadeesh K

Enclosed: Pdf (2 Pages)

Although you clearly have some understanding of the situation, I am afraid that you'd not have scored well. The type written portion is really pure introduction; yes it does help to set the scene of the context of your answer but you spent too long doing so, giving too much detail much of which was not relevant to your actual answer for part 1. If you felt you needed this then a tabular form with ticks for option 1 & 2 would have been both quicker and also give a better comparison of simularities / differences. One small thing- whereas an option 1 could be a pure protection system with no visibility in normal operation to the driver (and this is certainly something that you could have majored upon later) you seem to be describing ETCS levels 1 & 2 and there is a Driver machine Interface for both, albeit displaying different info.

Looking at your handwritten part which should be concentrating on RISKS it lists a range of FAULTS and FAILURES but does not actually attribut these to risks. Should be thinking of derailment at points, head-on collision, rear-end collision, entering an area that should be reserved for trackside workers under possession etc- in other words you need to identify the precursor to some form of accident- loss or damage to human life, property, environment etc.......
The question even uses the phrase "unsafe event"- your answer does not explicitly say what event follows "vehicle MMI fails to display" for example- you need to explain what is inherently UNSAFE about this or how something unsafe may happen as a consequence for which this might have been the root cause of the scenario leading toi accident.

Almost the only reference you have made is "degraded modes relying on human can lead to accidents due to misunderstandings, inaattention etc" and in truth you never actually even said that explicitly.

You did not pick up on the various other "hooks" in the question:
"absolute safety / ALARP"
"margins and tolerances"
"likelihood"

So I am afraid that you'd actually get few marks for what you had written- sorry if that sounds harsh but better I tell you now than the examiners in October....