Agreed- the blank does not encourage; the same is true for signal disengaging, last wheel replacement etc on the route & aspect CT as well as Time of Op locking and swinging overlap counter conditional on the points CTs yet I feel they are all needed.
As far as disengaging controls are concerned, I would follow the old Western Region practice of putting notes against the tracks in the tracks clear in aspect column. You wouldn't need to use the official WR #notes (predecessor to the national $ notes), but from distant memory:
#1 = stick track (the WR just used TC beyond signal without demanding berth TC occ)
#3 = stick track, but doesn't disengage when signal working auto
for forms of delayed replacement then in addition qualify by a 2nd note
#4 = non replacing whilst berth track occupied
#5 = non-replacing until stick track occupied and cleared.
Typically an entry could be:
AE#1#4#5, AF, AG, AH
so very economical with space and no need for an extra box on the CT and can get into the habit of always qualifying the first track in the tracks clear entry- so less chance of forgetting.
To return now to the actual question here; yes the NR tables do show the exit signal in two columns for good reason. Although usually the same entry in each,
1. a move to bufferstops does not prove the bufferstop alight and there is no sequence dependent upon it
2. a call-on move is set to exit signal button, but again not proved alight and no sequence depending on it
3. in isolated 3 aspect signalling, the route is set to the next red / green signal as the exit, but the spect sequence is derived from the intermediate yellow / green signal and the entrance signal proves BOTH the exit signal and its repeater alight
4. some sequences involve banner signals that are proved "alight or controls off" and which also affect aspect sequence, holding the signal in rear to yellow at best if not alight but off; "geen banners" are more complicated, as are co-actors and splitting distants.
Hence in preparing for the exam you need to consider how you would use the IRSE CT blank to be able to depict any of these possibilities- some might need the use of the last column to add as note, or
a cross reference from a relevant other column to a specific free-form entry on your initial CT Notes sheet; I thinkthis would certainly be the only option for a junction signal having a flashing aspect sequence in rear.
The reason why I would (in the simple case you are thinking about) have put the signal number at the top of the column is that to me
it is an important principle that on NR, for main routes at least, there is an end of movement authority proved alight and, where necessary to protect a junction or other high risk conflict, a TPWS loop proved active.
Agreed it may be better alternative to state this as an explicit assumption in your initial notes sheet. You still need to think about what to do in the less simple cases mentioned above.
However the important thing is, one way or the other, to make sure that the examiner knows you know the principle and knows that you have thought about it- that will be what gets you the mark; don't leave them wondering......
As far as disengaging controls are concerned, I would follow the old Western Region practice of putting notes against the tracks in the tracks clear in aspect column. You wouldn't need to use the official WR #notes (predecessor to the national $ notes), but from distant memory:
#1 = stick track (the WR just used TC beyond signal without demanding berth TC occ)
#3 = stick track, but doesn't disengage when signal working auto
for forms of delayed replacement then in addition qualify by a 2nd note
#4 = non replacing whilst berth track occupied
#5 = non-replacing until stick track occupied and cleared.
Typically an entry could be:
AE#1#4#5, AF, AG, AH
so very economical with space and no need for an extra box on the CT and can get into the habit of always qualifying the first track in the tracks clear entry- so less chance of forgetting.
To return now to the actual question here; yes the NR tables do show the exit signal in two columns for good reason. Although usually the same entry in each,
1. a move to bufferstops does not prove the bufferstop alight and there is no sequence dependent upon it
2. a call-on move is set to exit signal button, but again not proved alight and no sequence depending on it
3. in isolated 3 aspect signalling, the route is set to the next red / green signal as the exit, but the spect sequence is derived from the intermediate yellow / green signal and the entrance signal proves BOTH the exit signal and its repeater alight
4. some sequences involve banner signals that are proved "alight or controls off" and which also affect aspect sequence, holding the signal in rear to yellow at best if not alight but off; "geen banners" are more complicated, as are co-actors and splitting distants.
Hence in preparing for the exam you need to consider how you would use the IRSE CT blank to be able to depict any of these possibilities- some might need the use of the last column to add as note, or
a cross reference from a relevant other column to a specific free-form entry on your initial CT Notes sheet; I thinkthis would certainly be the only option for a junction signal having a flashing aspect sequence in rear.
The reason why I would (in the simple case you are thinking about) have put the signal number at the top of the column is that to me
it is an important principle that on NR, for main routes at least, there is an end of movement authority proved alight and, where necessary to protect a junction or other high risk conflict, a TPWS loop proved active.
Agreed it may be better alternative to state this as an explicit assumption in your initial notes sheet. You still need to think about what to do in the less simple cases mentioned above.
However the important thing is, one way or the other, to make sure that the examiner knows you know the principle and knows that you have thought about it- that will be what gets you the mark; don't leave them wondering......
(10-07-2013, 08:14 PM)dorothy.pipet Wrote: You say "Aspect sequence does not name the signal ahead- the IRSE’s CT blank does not encourage you to show but I think I would."
I thought about this because Network Rail RRI tables list the exit signal twice, and SSI tables state the signal(s) ahead with the Aspect Sequence information. These tables have the exit signal on the LHS so I decided that was sufficient.
Would you state the signal in the top row of the column?
PJW