Q2 MANAGING RISKS ASSOCIATED WITH REDUCING OVERLAP LENGTH

[oxfordjack]

How do you do.
Can you give me some hints how to answer that question?

Thank you

Question 2
Describe a suitable methodology for ensuring that the risk resulting from reducing the overlap length beyond a signal, on a railway which is not fitted with an automatic train protection system, remains tolerable?
Illustrate your answer with a diagram showing the inputs and outputs to and from the process.

[Peter]

(26-09-2009 04:28 PM)oxfordjack Wrote:  How do you do.
Can you give me some hints how to answer that question?

Thank you

Question 2
Describe a suitable methodology for ensuring that the risk resulting from reducing the overlap length beyond a signal, on a railway which is not fitted with an automatic train protection system, remains tolerable?
Illustrate your answer with a diagram showing the inputs and outputs to and from the process.

Bear in mind that I never did module 7, but the first part looks to me like a question that could be worded "describe a risk assessment process with which you are familiar and use it to identify risks arising from ... [insert text from question above]... The second part appears to narrow down the sort of risk assessment process a bit and this is where I start to get on shaky ground, but I think there is a quantified risk assessment process that has a tree structure and assigns probabilities to the events and hence allows a numerical calculation of the possible outcomes. In fact a quick web search on "Quantified Risk Assessment" brings up things like this from the IET. That is how I would go about it.

If he is around, Bigcheese might have a better idea than me.

[oxfordjack]

(26-09-2009 04:28 PM)oxfordjack Wrote:  How do you do.
Can you give me some hints how to answer that question?

Thank you

Question 2

Thank you.

[PJW]

(26-09-2009 04:28 PM)oxfordjack Wrote:  How do you do.
Can you give me some hints how to answer that question?

Thank you

Classic "risk" question which is very similar to what can come up in module 1; so approach it similarly. Split it down:
a) What is the chance / likelihood of a SPAD occuring at that particular signal
b) What would be the consequences of a SPAD if it did occur?

For part a) you could use a FAULT TREE (see IRSE News article earlier this year)
For part b) you could use an EVENT TREE (see link Peter gave)

Also inviting you to explain what you understand as a tolerable risk and how you would determine that in a particulr situation the risk was suitably low to be under that threshold.

So if you know your "Yellow Book" then you would be well on the way of answering this question- so overall my hint would be STUDY THE BOOK!

What you also need to know to fully answer this questionis how the basic theoretical process is actually applied in the particular scenario described; fundamentally need to describe the process used to "get the applicable numbers" that are used to weight the various scenarios. Ask yourself how the risk profile is affected by having a reduced length overlap and what the motivation for having a shorter than standard length overlap would be. Ask yourself whether there are any mitigations that would be associated with the shorter length.