Firstly I found a previously mis-filed thread on this question so I have moved it to the correct place and now merged with this new thread; hence it would be worth looking at the attempts posted higher up this combined thread and the comments thereon. Thought I had a sense of deja vu.
This question certainly related purely to a design error so you were right to restrict your answer to that scenario.
I think that I'd have attempted to broaden the interpretation of question to include the pre-testing period as well as the commissioning shift. This allows you to describe more available options which are dependent not only upon the severity of the error but also when it was identified- this clearly affects the possible solutions and the practicability of implementing within the required timescale.
Similarly you could discuss:
a) a missing vital control in interlocking wiring preventing the commissioning of a route; can the operators work the train service without it or do they just lose a facility only rarely needed? Can it be handsignalled?
b) a "cross between two bits" or an "incorrect inversion of a bit" in a software remote control system (i.e. there may have to be a short term "bodge" to get it working adequately functionally by amending wiring and then going back later when there is the ability to put in new data to correct properly and undue the hardware temporary fix),
c) a timing problem that just sometimes prevents a route being set; this isn't right but can be lived with for a bit by the signalman just trying again when it occurs,
d) the Train Describer stepping not working- perhaps a need to employ an extra signaller to compensate for this until it can be corrected,
e) a track circuit with over-long rail leads preventing full energisation of the relay and thus leaving the track prone to rightside failures in wet weather,
f) lack of polarity stagger at an IRJ; can the risk be adequately addressed by regular physical test of the integrity of that IRJ until the design can be amended and implemented?
and so on- you can invent lots of scenarios that all have a different consequence and possible mitigation and therefore explain that the options available depend on such circumstances.
Also could discuss the options available relating to the scale of the job; there may not always be a competent NR Project Engineer available at a time that a decision may be made,; on some minor works there may not even be any design cover on shift and even if they are on call there may only be a few hours in the commissioning period and not enough time to get a mod designed and installed, let alone tested. Alternatively the commissioning may be 54 hours or even more and there may be an office load of designers just waiting for something to do.
I think early on though I'd give the basic options:
1. Abandon the commissioning before the start
2. Get into the commissioning period, discover the error, decide no way forward and thus reverse the changes and re-test as it was before (obviously can't do this if P'Way have changed the track layout in the interim)
3. Modify within the commissioning shift
4. Deliberately overrun the booked shift in order to be able to rectify (having warned appropriate people and got acceptance!)
5. Commission most, but leave something booked off for later rectification.
6. Commission all but place on some operational restriction or procedure as a mitigation to compensate for some undesirable feature; return as soon as possible to resolve.
7. Commission all, but with special technical support to be on hand to overcome a problem as and when it arises, or in other circumstances institute some regular inspection regime to address by other means whatever risk not being controlled in the manner that ideally it should be.
I think your answer went into too much detail re the Test Log procedure; I think sensible to mention as it is a consequential action, and an outline to demonstrate that you know what a Test Log is but specifying all the entries on it went further than needed. Definitely don't need the info re how a T/L is transmitted to a remote design office- although arguably on topic the answer isn't strictly relevant to precisely what was asked and this was OPTIONS AVAILABLE.
Also a few points of detail; the TiC can only propose T/L for deferral, it is the Infrastructure Manager Representative who accepts this proposal. Also would tend to send T/L to design to think about before considering how urgent to resolve (until know potential solution can't judge whether practicable and therefore what options available), though obviously if there are several then the TiC may hold back the ones they consider less important to avoid detracting from the serious one (human nature is that the designer would tend to do the one which is easier, rather than the most urgent / important!).
Also the tester / TiC should definitely NOT suggest a solution to the designer; I know it happens and yes there are times that a certain amount of guidance of what would / would not be practicable to implement on site is appropriate, but it is not something that should be stated in an IRSE Exam answer.
Other than that I agree with Jerry that your answer was on the right lines; I think that structuring as a series of bullet points or as lines of a table would make it far more obvious how many options you were suggesting and in what circumstances each may be applicable.
Your last paragraph was the best and you should have done more in the same vein; hopefully I have suggested above some avenues down which you could have gone to expand the scope of the question to give yourself more scope in describing options.
Obviously this is where experience comes to the fore; I have been a tester for years in a whole range of circumstances and thus I would find no problem in listing a very wide range of circumstances as I have lived through them. Some can be quite bizzare; there was one mechanical signalbox at a train depot where the mechanical ground discs being replaced by LED GPLs. We thought all was fine and commissioned in the small hours of the morning and then the design error became obvious. Train shunted out of depot, across a set of points but there are no track circuits. Signalman says "how the &#$# can I tell that the train has cleared the points before I attempt to move them?; I used to be able to see the backlight from the shunting disc when he had got behind it, now I ain't got a *%$@#ing clue......" We got a tester to donate his head torch and attached it to the GPL as a temporary expedient and the signalman was happy again.
This question certainly related purely to a design error so you were right to restrict your answer to that scenario.
I think that I'd have attempted to broaden the interpretation of question to include the pre-testing period as well as the commissioning shift. This allows you to describe more available options which are dependent not only upon the severity of the error but also when it was identified- this clearly affects the possible solutions and the practicability of implementing within the required timescale.
Similarly you could discuss:
a) a missing vital control in interlocking wiring preventing the commissioning of a route; can the operators work the train service without it or do they just lose a facility only rarely needed? Can it be handsignalled?
b) a "cross between two bits" or an "incorrect inversion of a bit" in a software remote control system (i.e. there may have to be a short term "bodge" to get it working adequately functionally by amending wiring and then going back later when there is the ability to put in new data to correct properly and undue the hardware temporary fix),
c) a timing problem that just sometimes prevents a route being set; this isn't right but can be lived with for a bit by the signalman just trying again when it occurs,
d) the Train Describer stepping not working- perhaps a need to employ an extra signaller to compensate for this until it can be corrected,
e) a track circuit with over-long rail leads preventing full energisation of the relay and thus leaving the track prone to rightside failures in wet weather,
f) lack of polarity stagger at an IRJ; can the risk be adequately addressed by regular physical test of the integrity of that IRJ until the design can be amended and implemented?
and so on- you can invent lots of scenarios that all have a different consequence and possible mitigation and therefore explain that the options available depend on such circumstances.
Also could discuss the options available relating to the scale of the job; there may not always be a competent NR Project Engineer available at a time that a decision may be made,; on some minor works there may not even be any design cover on shift and even if they are on call there may only be a few hours in the commissioning period and not enough time to get a mod designed and installed, let alone tested. Alternatively the commissioning may be 54 hours or even more and there may be an office load of designers just waiting for something to do.
I think early on though I'd give the basic options:
1. Abandon the commissioning before the start
2. Get into the commissioning period, discover the error, decide no way forward and thus reverse the changes and re-test as it was before (obviously can't do this if P'Way have changed the track layout in the interim)
3. Modify within the commissioning shift
4. Deliberately overrun the booked shift in order to be able to rectify (having warned appropriate people and got acceptance!)
5. Commission most, but leave something booked off for later rectification.
6. Commission all but place on some operational restriction or procedure as a mitigation to compensate for some undesirable feature; return as soon as possible to resolve.
7. Commission all, but with special technical support to be on hand to overcome a problem as and when it arises, or in other circumstances institute some regular inspection regime to address by other means whatever risk not being controlled in the manner that ideally it should be.
I think your answer went into too much detail re the Test Log procedure; I think sensible to mention as it is a consequential action, and an outline to demonstrate that you know what a Test Log is but specifying all the entries on it went further than needed. Definitely don't need the info re how a T/L is transmitted to a remote design office- although arguably on topic the answer isn't strictly relevant to precisely what was asked and this was OPTIONS AVAILABLE.
Also a few points of detail; the TiC can only propose T/L for deferral, it is the Infrastructure Manager Representative who accepts this proposal. Also would tend to send T/L to design to think about before considering how urgent to resolve (until know potential solution can't judge whether practicable and therefore what options available), though obviously if there are several then the TiC may hold back the ones they consider less important to avoid detracting from the serious one (human nature is that the designer would tend to do the one which is easier, rather than the most urgent / important!).
Also the tester / TiC should definitely NOT suggest a solution to the designer; I know it happens and yes there are times that a certain amount of guidance of what would / would not be practicable to implement on site is appropriate, but it is not something that should be stated in an IRSE Exam answer.
Other than that I agree with Jerry that your answer was on the right lines; I think that structuring as a series of bullet points or as lines of a table would make it far more obvious how many options you were suggesting and in what circumstances each may be applicable.
Your last paragraph was the best and you should have done more in the same vein; hopefully I have suggested above some avenues down which you could have gone to expand the scope of the question to give yourself more scope in describing options.
Obviously this is where experience comes to the fore; I have been a tester for years in a whole range of circumstances and thus I would find no problem in listing a very wide range of circumstances as I have lived through them. Some can be quite bizzare; there was one mechanical signalbox at a train depot where the mechanical ground discs being replaced by LED GPLs. We thought all was fine and commissioned in the small hours of the morning and then the design error became obvious. Train shunted out of depot, across a set of points but there are no track circuits. Signalman says "how the &#$# can I tell that the train has cleared the points before I attempt to move them?; I used to be able to see the backlight from the shunting disc when he had got behind it, now I ain't got a *%$@#ing clue......" We got a tester to donate his head torch and attached it to the GPL as a temporary expedient and the signalman was happy again.
(19-08-2011, 11:27 AM)Jerry1237 Wrote: Hort,
I think it is a very reasonable answer. One comment is testers are not just there to find design errors but build and installation errors too.
Again, the purpose of the exam is to inform the examiner the candidate understands the principles of the answer and not the abilty to write War and Peace.
I'll leave others to critique your answer but it is certainly a good start.
Jerry
PJW