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]

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]

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

Thank you

Question 2

Thank you.

[PJW]

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.

[Prm]

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.

Hi

with respect to this question I can think about some methodology like:

Providing repeater signal
Provide time table so that two train does not come at the same time on that route.
Provide approach clearing of the signal
Double red signal
Restricting speed in that particular area.
Providing AWS

Can any one tell about diagram showing the inputs and outputs to and from the process. I think this is a decision making diagram.

Thanks

[PJW]

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.

Hi

with respect to this question I can think about some methodology like:

1. Providing repeater signal
2. Provide time table so that two train does not come at the same time on that route.
3. Provide approach clearing of the signal
4. Double red signal
5. Restricting speed in that particular area.
6. Providing AWS

Can any one tell about diagram showing the inputs and outputs to and from the process. I think this is a decision making diagram.

Thanks

For the exam answer you should indicate WHY your suggestions would reduce risk.
1. Reduces chance of SPAD that might exist if signal doesn't have good sighting
2. Reduces the chance of the signal being encountered at danger and thus vulnerable to SPAD
3. WHICH SIGNAL? Actually this may pre-condition the driver into expecting last minute clearance and therefore INCREASE chance of SPAD when it doesn't. What you should have made clear was that it is the signal previous to the one having the sub-standard overlap which is kept at red to reduce the train speed and this had the effect of reducing likelihood of SPAD at the one having short overlap.
4. Again you need to explain what this is and how it achieves (similar in some ways to 3)
5. Reduces chances of SPAD and may mean that any SPAD which does occur is at a lower speed, thus increasing the chances of the driver being able to stop within the overlap length.
6. Reduces chances of driver failing to apply brakes sufficiently prior to the signal at red and also giving another prompt when getting close to the red signal make encourage a last minute brake application thus reducing the chances of train going beyond the overlap.

BEWARE THOUGH- the question was about the METHODOLOGY of the process- NOT asking for specific mitigations!!!
I suggest that the diagram could be the so-called "bow tie" featuring a fault tree with the "Top Event" being the SPAD and then an Event Tree that looks at the probability of the train actually being safely brought to rest within the overlap or passing beyond it.