02-10-2012, 12:26 PM
Hi again Alex
Sorry for the slow reply- here are further comments on your route control tables:
Route 216A(M)
Route controls:
Good- opposing routes handled correctly.
Selection of available swinging overlap also correct.
I know what you’re trying to express, but it’s not the custom to state “OFZ-BA free”, as this assumes you have a separate control table expressing how OFZ-BA operates. In practice, you need to end up writing a very complex expression to express how “OFZ-BA” is free, in terms of other routes, track circuits and points – see my model answer. Realistically, you won’t have time in the exam to handle this, and the examiners are unlikely to award many marks for it - you’re better applying effort to the easier stuff.
Signal controls
Also good, but there’s no need to check OFZ-BA to be free: the setting of this route should impose locking to prevent other conflicting routes/ overlaps being set, expressed on the CTs for the other routes.
You missed the flashing yellow condition in the aspect sequence.
It might also be worth adding the “stick unsetting” conditions – this has to be a special control as there are no columns provided.
348C(M)
144 points missed.
Route controls also require 321 normal - single line release- this is effectively a “directly opposing route”
Route controls also need to treat 343A(M) as an indirectly opposing route – if a train has arrived at 347 signal safely, 131 points will be locked under the train, but if the train SPADs at 347, 131 points will release and the SPAD, while still in the overlap will lose its opposing locking protection.
Foul track circuit FG missed from signal controls
349D© (route to platform 2)
You have provided controls for route 349C(M) - platform 1 instead. However, they look correctly handled.
The route controls need to specify that the platform should have at least one occupied track circuit at time of route setting.
We don’t know how the examiners treat this situation.
• Certainly you won’t get any direct credit for a correct answer to the wrong question.
• One school of thought argues that if 25% of the question is not answered, the maximum you can score is 75%, even if the remainder is answered perfectly
• An alternative argument could be that you have already demonstrated knowledge of how to specify all the different control functions in other parts of the question, only leaving features unique to the part you missed – such as controls unique to call-on class routes. In this case, you might be able to score 90% (say) despite your omission.
I suspect that the actual view taken in marking is somewhere between the two extremes expressed above.
In summary, your tables have correctly captured most of the features, including complex features such as indirectly opposing routes and swinging overlaps, so this answer would score well in the exam.
You annotations seem to show that you spent over 30 minutes on the three route control tables, and presumably another 10-15 on the points. Therefore, some care is needed to budget time fairly in the exam and strictly move on when the 30 minutes per question is up. the time is always better spent scoring the "easy firsy 50%" marks of two long answer questions.
Good work - good luck for the exam!
Reuben
Sorry for the slow reply- here are further comments on your route control tables:
Route 216A(M)
Route controls:
Good- opposing routes handled correctly.
Selection of available swinging overlap also correct.
I know what you’re trying to express, but it’s not the custom to state “OFZ-BA free”, as this assumes you have a separate control table expressing how OFZ-BA operates. In practice, you need to end up writing a very complex expression to express how “OFZ-BA” is free, in terms of other routes, track circuits and points – see my model answer. Realistically, you won’t have time in the exam to handle this, and the examiners are unlikely to award many marks for it - you’re better applying effort to the easier stuff.
Signal controls
Also good, but there’s no need to check OFZ-BA to be free: the setting of this route should impose locking to prevent other conflicting routes/ overlaps being set, expressed on the CTs for the other routes.
You missed the flashing yellow condition in the aspect sequence.
It might also be worth adding the “stick unsetting” conditions – this has to be a special control as there are no columns provided.
348C(M)
144 points missed.
Route controls also require 321 normal - single line release- this is effectively a “directly opposing route”
Route controls also need to treat 343A(M) as an indirectly opposing route – if a train has arrived at 347 signal safely, 131 points will be locked under the train, but if the train SPADs at 347, 131 points will release and the SPAD, while still in the overlap will lose its opposing locking protection.
Foul track circuit FG missed from signal controls
349D© (route to platform 2)
You have provided controls for route 349C(M) - platform 1 instead. However, they look correctly handled.
The route controls need to specify that the platform should have at least one occupied track circuit at time of route setting.
We don’t know how the examiners treat this situation.
• Certainly you won’t get any direct credit for a correct answer to the wrong question.
• One school of thought argues that if 25% of the question is not answered, the maximum you can score is 75%, even if the remainder is answered perfectly
• An alternative argument could be that you have already demonstrated knowledge of how to specify all the different control functions in other parts of the question, only leaving features unique to the part you missed – such as controls unique to call-on class routes. In this case, you might be able to score 90% (say) despite your omission.
I suspect that the actual view taken in marking is somewhere between the two extremes expressed above.
In summary, your tables have correctly captured most of the features, including complex features such as indirectly opposing routes and swinging overlaps, so this answer would score well in the exam.
You annotations seem to show that you spent over 30 minutes on the three route control tables, and presumably another 10-15 on the points. Therefore, some care is needed to budget time fairly in the exam and strictly move on when the 30 minutes per question is up. the time is always better spent scoring the "easy firsy 50%" marks of two long answer questions.
Good work - good luck for the exam!
Reuben