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2016 Q10 Aspect Sequence Chart
#1
Hi all,

I am looking at 2016 Q10 and I just want you guys to confirm my assumptions are correct, because the assumptions I think I'm using are creating an ungodly complicated aspect sequence diagram, and I havn't come across such a complicated one in any study materials so far which is making me think my assumptions are incorrect.

I have gotten all my info from the modern signalling handbook 5th edition or from the IRSE mod3 study guide.

Assumption 1: all signals capable of showing stop, therefore no distant signals
Assumption 2: using standard overlap of 180m, i.e. there are no reduced overlaps
Assumption 3: Signal sighting is all OK, i.e. reading times are all above 8 seconds, there are no obstructions to this, as such I don't need any banner/splitting banner repeater signals.
Assumption 4: The signals are spaced too close for 3-aspect so it must be 4 aspect signalling (modern signalling handbook page 62 says 3 aspect ones are between 1600 and 2400 m apart)

Assumption 5: Signal 23, the turnout is 130kmph down to 80kmph, this delta is >16kmph so I need approach control, the initial speed is >96kmph so it can't be "Approach control from yellow preceeded by a double yellow" type, and Approach control from Red seems too restrictive for this so I'm thinking Approach control from yellow with flashing yellows. 

Assumption 6: it says this layout has stopping and non-stopping trains on the up fast so that means Signal 27 turnout has the same approach control as assumption 5

Assumption 7: Signal 29 the turnout is 80kmph down to 65kmph, as this delta is <16kmph I do not need approach control,


I guess the fact that I think 23 and 27 both need approach control with flashing yellows is making my aspect sequence diagram huge and complicated. What do you think of these assumptions?

Oliver
#2
Post cross-posted. See here.
Cyclisme24
#3
(19-04-2017, 01:06 PM)obennett Wrote: Hi all,

I am looking at 2016 Q10 and I just want you guys to confirm my assumptions are correct, because the assumptions I think I'm using are creating an ungodly complicated aspect sequence diagram, and I havn't come across such a complicated one in any study materials so far which is making me think my assumptions are incorrect.

I have gotten all my info from the modern signalling handbook 5th edition or from the IRSE mod3 study guide.

Assumption 1: all signals capable of showing stop, therefore no distant signals
Assumption 2: using standard overlap of 180m, i.e. there are no reduced overlaps
Assumption 3: Signal sighting is all OK, i.e. reading times are all above 8 seconds, there are no obstructions to this, as such I don't need any banner/splitting banner repeater signals.
Assumption 4: The signals are spaced too close for 3-aspect so it must be 4 aspect signalling (modern signalling handbook page 62 says 3 aspect ones are between 1600 and 2400 m apart)

Assumption 5: Signal 23, the turnout is 130kmph down to 80kmph, this delta is >16kmph so I need approach control, the initial speed is >96kmph so it can't be "Approach control from yellow preceeded by a double yellow" type, and Approach control from Red seems too restrictive for this so I'm thinking Approach control from yellow with flashing yellows. 

Assumption 6: it says this layout has stopping and non-stopping trains on the up fast so that means Signal 27 turnout has the same approach control as assumption 5

Assumption 7: Signal 29 the turnout is 80kmph down to 65kmph, as this delta is <16kmph I do not need approach control,


I guess the fact that I think 23 and 27 both need approach control with flashing yellows is making my aspect sequence diagram huge and complicated. What do you think of these assumptions?

Oliver
Assumption 1: Not an assumption- the question explicitly states this
Assumption 2: Agreed probably a reasonable assumption to make initially; I haven't worked it through but it may be worth bringing in ROLs later when talking about "restrictions"
Assumption 3: Reasonable.  I certainly would have mentioned sighting of route indicator compared with main aspect.  Possibly also re reading through, particularly thinking about approach release
Assumption 4:  Certainly the exam layout recently very much focussed on how braking distance compares with signal spacing.  4 aspects is one solution, but do remember that can use a modified 3 aspect sequence (approach releasing a signal if the next is at danger and is less than full braking distance) can be a useful option worth exploring.
Assumption 5: MAY-FA does look appropriate
Assumption 6: Not so sure.  There are restrictions relating to consecutive flashing aspect sequence and in particular a signal should not be flashing yellow whilst itself displaying a PLJI. You might find that 27 routed to the branch may be different from 29 routed to the branch.  In fact that differential is spookily just less than 16km/h as you have stated in assumption 7 so I agree that this can be MAF.

So yes I think you are correct; it looks sensible to provide both the flashing aspects for the route from 27 to 51 as well as for the route from 23 to 29

Remember that the aspect sequence question is not about producing quantity, but demonstrating that you truly have an understanding of what you are doing.  If you can draw one flashing aspect sequence, surely you can draw two; you do need to think carefully about how you space out the signals on the piece of paper, but yes it seems to be that you have essentially solved the puzzle.  However if you are going for 4 aspects then you will need to consider the transitions from and back to 3 aspects as well.

Pre approx. 2011 the aspect sequence chart was fairly standard and an easy option for people to mug up on to get through the exam; it has now changed character.  I do agree that the Study Pack has perhaps over concentrated in this area more on teaching the basics rather than being aligned to the type of question which is typical in recent years- there is a feedback form in the module so I suggest you make use of that.
PJW


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