https://irse.signalpost.org/ Tue, 11 Aug 2026 18:35:27 +0000 MyBB https://irse.signalpost.org/showthread.php?tid=2314 Sun, 09 Sep 2018 08:08:11 +0000 hayesip]]> https://irse.signalpost.org/showthread.php?tid=2314 I have attempted Q2 for the 2012 Module 5 exam and would really appreciate some feedback. This is my first attempt at producing a fault tree. I thought I'd better learn how to do them as they seem to be a popular question.

Many thanks in advance.

regards Ian]]> I have attempted Q2 for the 2012 Module 5 exam and would really appreciate some feedback. This is my first attempt at producing a fault tree. I thought I'd better learn how to do them as they seem to be a popular question.

Many thanks in advance.

regards Ian]]> https://irse.signalpost.org/showthread.php?tid=2291 Mon, 14 May 2018 15:31:44 +0000 alexgoei]]> https://irse.signalpost.org/showthread.php?tid=2291
Am pleased to submit my answer for the 2016 Q1 on points out of correspondence.

Any comments most welcome please


Alex]]>
Am pleased to submit my answer for the 2016 Q1 on points out of correspondence.

Any comments most welcome please


Alex]]> https://irse.signalpost.org/showthread.php?tid=1903 Mon, 30 Mar 2015 12:48:21 +0000 asrisaku]]> https://irse.signalpost.org/showthread.php?tid=1903
I am trying to practice a fault tree question and I realise that I am quite weak of understanding railway application due to limitation of knowledge.

I would be very happy if anyone can point out what I need to do more research for this subject and what I can improve.

Thanks in advance!!!

Best regards,
Arnut]]>
I am trying to practice a fault tree question and I realise that I am quite weak of understanding railway application due to limitation of knowledge.

I would be very happy if anyone can point out what I need to do more research for this subject and what I can improve.

Thanks in advance!!!

Best regards,
Arnut]]> https://irse.signalpost.org/showthread.php?tid=975 Thu, 16 Feb 2012 11:35:22 +0000 pieman31]]> https://irse.signalpost.org/showthread.php?tid=975
I had to knock up a fault tree for a paper I'm writing at work. I'll share an early version here as an exmaple, be it good or bad, to stimulate your thoughts and possibly fuel a discussion...

To provide a bit of context, the fault tree represents some failure modes applicable to a Westinghouse Signal Machine, which, is used to operate Semaphore Signal Arms in both upper and lower quadrant arrangements.

In terms of the exam, granted it took me a while to draw on a computer but the original draft took about 25 minutes (too illegible for use on here!) given that I had a full set of FMEA to work from.

Hope you find it useful.....

Cheers.]]>
I had to knock up a fault tree for a paper I'm writing at work. I'll share an early version here as an exmaple, be it good or bad, to stimulate your thoughts and possibly fuel a discussion...

To provide a bit of context, the fault tree represents some failure modes applicable to a Westinghouse Signal Machine, which, is used to operate Semaphore Signal Arms in both upper and lower quadrant arrangements.

In terms of the exam, granted it took me a while to draw on a computer but the original draft took about 25 minutes (too illegible for use on here!) given that I had a full set of FMEA to work from.

Hope you find it useful.....

Cheers.]]> https://irse.signalpost.org/showthread.php?tid=725 Tue, 25 Jan 2011 12:38:03 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=725
http://www.yellowbook-rail.org.uk/resour...odels.html

Looking at the contributors to a typical one (GW ATP) then it includes the names of two of those on the IRSE Exam committee......

Also if you navigate up a level from this page of Siganlling Risk Models, then there also other equivelent pages for Telecomms and other Elecctification & Plant to look at as well.]]>
http://www.yellowbook-rail.org.uk/resour...odels.html

Looking at the contributors to a typical one (GW ATP) then it includes the names of two of those on the IRSE Exam committee......

Also if you navigate up a level from this page of Siganlling Risk Models, then there also other equivelent pages for Telecomms and other Elecctification & Plant to look at as well.]]> https://irse.signalpost.org/showthread.php?tid=481 Thu, 22 Jul 2010 17:12:36 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=481 Quote:Hi,
I want to attempt the fault tree for Points. I request you to guide me to do that as the way you helped for DC Track Circuits in the below thread:

http://www.irseexam.co.uk/showthread.php?tid=294.

Please help.
First think about what "points failure" means. You ought to be able to list a number of different "top events"- diverse ways in which a set of points might adversely affect the efficient and safe operation of the railway. Some may cause delay or prevent the passage of traffic altogether, others may be immediately and directly dangerous, others perhaps a latent fault which lies dormant for a while before having its adverse effect. In doing this you are looking "top down" by regarding "points" as components within the entire railway system.

Then think about all the things that could go wrong and compile yourself a list of faults.
a) Think about the whole range of component parts: mechanical, electrical, signalling, P'Way, power, within the mechanism itself and all its related support equipment and interconnections.
b) Also think about the manner in which they go wrong: normal physical wear, deterioration due to age, chemical attack, abnormal loading, mechanical shock, vibration, electrical overload, extremes of weather, user abuse, vandalism .......
In doing this you are looking "bottom up" by regarding "points" as a system composed of smaller components.

So try to pair things up in typical combinations that displays your knowledge of point mechanisms and of failure modes:
part a may seize up (why?)
part b may loosen (why?)
part c may leak (why?)
part d may become detached (why?)
part e may burn out (why?)
part f may fracture (why?)
part g may become out of alignment (why?)
..................................................
something external x may obstruct (why?)
something external y may cause physical damage (why?)
someone z may do something careless (why?)

Now what you now need to do is to consider what faults in what combination and in what circumstances conspire to create the various top level events which you identified initially.

Connect up in a logical manner using AND / OR gates to combine the various threads suitable, then job done.
Simples.

So have a go and submit your efforts.
Use the example for a signal in the GM Rail event thread as an example from which to work.]]> Quote:Hi,
I want to attempt the fault tree for Points. I request you to guide me to do that as the way you helped for DC Track Circuits in the below thread:

http://www.irseexam.co.uk/showthread.php?tid=294.

Please help.
First think about what "points failure" means. You ought to be able to list a number of different "top events"- diverse ways in which a set of points might adversely affect the efficient and safe operation of the railway. Some may cause delay or prevent the passage of traffic altogether, others may be immediately and directly dangerous, others perhaps a latent fault which lies dormant for a while before having its adverse effect. In doing this you are looking "top down" by regarding "points" as components within the entire railway system.

Then think about all the things that could go wrong and compile yourself a list of faults.
a) Think about the whole range of component parts: mechanical, electrical, signalling, P'Way, power, within the mechanism itself and all its related support equipment and interconnections.
b) Also think about the manner in which they go wrong: normal physical wear, deterioration due to age, chemical attack, abnormal loading, mechanical shock, vibration, electrical overload, extremes of weather, user abuse, vandalism .......
In doing this you are looking "bottom up" by regarding "points" as a system composed of smaller components.

So try to pair things up in typical combinations that displays your knowledge of point mechanisms and of failure modes:
part a may seize up (why?)
part b may loosen (why?)
part c may leak (why?)
part d may become detached (why?)
part e may burn out (why?)
part f may fracture (why?)
part g may become out of alignment (why?)
..................................................
something external x may obstruct (why?)
something external y may cause physical damage (why?)
someone z may do something careless (why?)

Now what you now need to do is to consider what faults in what combination and in what circumstances conspire to create the various top level events which you identified initially.

Connect up in a logical manner using AND / OR gates to combine the various threads suitable, then job done.
Simples.

So have a go and submit your efforts.
Use the example for a signal in the GM Rail event thread as an example from which to work.]]> https://irse.signalpost.org/showthread.php?tid=466 Thu, 08 Jul 2010 19:06:54 +0000 PJW]]> https://irse.signalpost.org/showthread.php?tid=466
1. It is good that right side and wrong side failures have been separately considered

2. Need to be careful to distinguish between AND and OR; all seem to have been drawn as ANDs, whereas most at least should have been ORs

3. Conventionally the failures are drawn at the top of the sheet of paper and the various faults in a heirarchy below; this presentation reads left to right- it isn't wrong but probably best to do conventionally.

4. I liked the portion of the tree which leads to NO POWER (although where it said "head transformer" it presumably means "feedset transformer")

5. Other elements should have been broken down in this manner rather than simply all summating all at one node. For example it would have been easy to have separated the faults:
a) leading to high resistance between feed and relay,
and
b) leading to excessive leakage diverting current from track relay
and
c) opposing voltage from neighbouring track imposed due to failed Insulated Rail Joint
any one of which would cause insufficient pick up current.

6. Then for example item 5b could then have been further broken down into the various causes of poor ballast resistance (flooding, contamination, failed rail insulations / pads, point stretcher insulations),

7. Could have considered also the TR failing to pick because it had become open circuit, mechanically jammed. Also it could have high resistance contact or line circuit to TPR in interlocking itself having a fault wheres the actual track circuit on site was working fine.

8. In summary I think that you had a reasonable number of failures of different types, but you should have presented with groupings and sub-groupings to get a more heirarchical structure. The idea is that you can "drill down" from the top event and get more and more levels of detail, with a range of different types of faults then at the next level down a range of different ways in which that particular type of fault can occur from different lower level causes.

Also it would have been good to have demonstrated some combinational faults.
e.g. track set up in wet conditions with too low a drop shunt
AND
ballast resistance gets very high during hot weather
GIVES
train shunts insufficient current to cause TR to drop.

Similarly you could have assumed duplicated rail leads from location to rails. Cable can fail and track carries on working ok, but if this situation is not revealed by routine testing or chance inspectiion and then the other lead fails, then the track will fail.

I note you had as a fault "pipeline crossing railay line"; by itself this is not a FAULT. It is a relevant factor so you need to combine it with some act or omission that turns the result into a fault.

9. Would have been good to have demonstrated that you knew the role of a Fault Tree is to be able to feed in numerical estimates of probabilities of the various fault events at the roots of the tree, to be able to do some probabilistic number crunching to give estimates of probabilities for the various branches of the tree.

10. Overall it would probably have been aound a Pass- certainly have the general idea both of Fault Trees and Track Circuits but not quite there; presents a picture but it is a little "out of focus"

==========================================================================
I assume that you have found the previous discussion of track circuit fault tree but did you download
a) the attachment for the signal lamp out (to look at the presentation) and
b) read the IRSE News article?
These should help]]>
1. It is good that right side and wrong side failures have been separately considered

2. Need to be careful to distinguish between AND and OR; all seem to have been drawn as ANDs, whereas most at least should have been ORs

3. Conventionally the failures are drawn at the top of the sheet of paper and the various faults in a heirarchy below; this presentation reads left to right- it isn't wrong but probably best to do conventionally.

4. I liked the portion of the tree which leads to NO POWER (although where it said "head transformer" it presumably means "feedset transformer")

5. Other elements should have been broken down in this manner rather than simply all summating all at one node. For example it would have been easy to have separated the faults:
a) leading to high resistance between feed and relay,
and
b) leading to excessive leakage diverting current from track relay
and
c) opposing voltage from neighbouring track imposed due to failed Insulated Rail Joint
any one of which would cause insufficient pick up current.

6. Then for example item 5b could then have been further broken down into the various causes of poor ballast resistance (flooding, contamination, failed rail insulations / pads, point stretcher insulations),

7. Could have considered also the TR failing to pick because it had become open circuit, mechanically jammed. Also it could have high resistance contact or line circuit to TPR in interlocking itself having a fault wheres the actual track circuit on site was working fine.

8. In summary I think that you had a reasonable number of failures of different types, but you should have presented with groupings and sub-groupings to get a more heirarchical structure. The idea is that you can "drill down" from the top event and get more and more levels of detail, with a range of different types of faults then at the next level down a range of different ways in which that particular type of fault can occur from different lower level causes.

Also it would have been good to have demonstrated some combinational faults.
e.g. track set up in wet conditions with too low a drop shunt
AND
ballast resistance gets very high during hot weather
GIVES
train shunts insufficient current to cause TR to drop.

Similarly you could have assumed duplicated rail leads from location to rails. Cable can fail and track carries on working ok, but if this situation is not revealed by routine testing or chance inspectiion and then the other lead fails, then the track will fail.

I note you had as a fault "pipeline crossing railay line"; by itself this is not a FAULT. It is a relevant factor so you need to combine it with some act or omission that turns the result into a fault.

9. Would have been good to have demonstrated that you knew the role of a Fault Tree is to be able to feed in numerical estimates of probabilities of the various fault events at the roots of the tree, to be able to do some probabilistic number crunching to give estimates of probabilities for the various branches of the tree.

10. Overall it would probably have been aound a Pass- certainly have the general idea both of Fault Trees and Track Circuits but not quite there; presents a picture but it is a little "out of focus"

==========================================================================
I assume that you have found the previous discussion of track circuit fault tree but did you download
a) the attachment for the signal lamp out (to look at the presentation) and
b) read the IRSE News article?
These should help]]> https://irse.signalpost.org/showthread.php?tid=294 Tue, 29 Sep 2009 12:06:13 +0000 priyman]]> https://irse.signalpost.org/showthread.php?tid=294
Has anyone made an attempt or know where we can get example fault trees (rather than the analysis/method - which is in the yellow book and elsewhere on this forum).

Thanks,

Priyank]]>
Has anyone made an attempt or know where we can get example fault trees (rather than the analysis/method - which is in the yellow book and elsewhere on this forum).

Thanks,

Priyank]]> https://irse.signalpost.org/showthread.php?tid=173 Wed, 11 Feb 2009 11:47:57 +0000 Douglas]]> https://irse.signalpost.org/showthread.php?tid=173
D.]]>
D.]]>