The point machine may have an internal FPL but that certainly is an assumption that would need to be stated by the candidate.
In this sort of layout I would not be in the slightest surprised that there would NOT be; a guess would be that when initially converted to motor operation that there would have been no FPL (signal engineers in say the 1960s were - to our eyes- very parsimonious and keen to keep to the minimum the "initial first cost" even at the expense of greater "whole life cost". We should not criticise them for this since the world was different then- labour was relatively cheaper compared to equipment than nowadays; also the poor man actually often does not have the wherewithall to invest to save money long term, even if they know that theoretically they should be so doing. Actually many such places may well since have acquired FPLs by default, as should there have been a need to replace the point machine, nowadays we have standardised only on machines with internal FPL).
Slightly out of context, but be aware that London Underground is as part of the current upgrade to Circle / District / Hammersmith & City / Metropolitan lines is needing to upgrade some 30 machines to allow reversible use of the infrastructure (albeit I think that it is more of a question of fitting additional Ground Locks than FPLs, but conceptually it is the same issue).
This demonstrates that it is important to realise that some signalling standards are in reality perpetuated somewhere for at least a generation after they have officially been superseded for new work. One of the things that one only learns from experience.
Therefore I think that the identification in the answer that the points may well not have an FPL was entirely valid, although I agree with Jerry that in the scenario given the solution would have been "scotch the open switch, clip the closed switch and padlock"
In this sort of layout I would not be in the slightest surprised that there would NOT be; a guess would be that when initially converted to motor operation that there would have been no FPL (signal engineers in say the 1960s were - to our eyes- very parsimonious and keen to keep to the minimum the "initial first cost" even at the expense of greater "whole life cost". We should not criticise them for this since the world was different then- labour was relatively cheaper compared to equipment than nowadays; also the poor man actually often does not have the wherewithall to invest to save money long term, even if they know that theoretically they should be so doing. Actually many such places may well since have acquired FPLs by default, as should there have been a need to replace the point machine, nowadays we have standardised only on machines with internal FPL).
Slightly out of context, but be aware that London Underground is as part of the current upgrade to Circle / District / Hammersmith & City / Metropolitan lines is needing to upgrade some 30 machines to allow reversible use of the infrastructure (albeit I think that it is more of a question of fitting additional Ground Locks than FPLs, but conceptually it is the same issue).
This demonstrates that it is important to realise that some signalling standards are in reality perpetuated somewhere for at least a generation after they have officially been superseded for new work. One of the things that one only learns from experience.
Therefore I think that the identification in the answer that the points may well not have an FPL was entirely valid, although I agree with Jerry that in the scenario given the solution would have been "scotch the open switch, clip the closed switch and padlock"
(25-08-2011, 09:37 AM)Jerry1237 Wrote: Hello,
Your answer seems to address a couple of methods of degraded working. However, there are a few things I'd like to add.
1) It is mentioned to add an FPL to 22. Simplistically, the need to degraded working is often short notice (as in this case) and fitting of additional kits is prohibitive due to time/cost/effort. However, in this situation, note the comment under the 'box stating all points are motor driven. Therefore, it is a reasonable assumption there is an internal FPL!
PJW