17-08-2015, 12:56 AM
(This post was last modified: 18-08-2015, 09:37 PM by PJW.
Edit Reason: spelling!
)
[*]MikeMurphy
[quote pid='5878' dateline='1439753918']
Hi,
This is my first attempt at answering an IRSE question and I have attempted to answer a question on 'the principal purpose of a signalling system' and I'm just looking to get some advice guidance on;
Have I understood the question correctly
If so is the content enough to justify the marks for it
How could I improve my answer
Thanks
Mike
[/quote]
[*]
Mike,
You don't say (and I haven't investigated) the module in which asked but I assume mod3 given the section in which posted. The wording does sound a bit mod 7ish though and I would certainly answer it in terms of "functional requirements" but aligning to Signalling Principles. Hence I would say the 10 principal purposes would be:
1. Centralise control so the various points can rapidly be set to the required position for a movement and the driver then given the movement authority (conveying all necessary information about the movement to be made) so that the train may proceed without any undue delay.
2. Prevent conflicting movements from taking place simultaneously so as to provide safety at junctions and avoid the possibility of head on collisions occurring; a special case of this can be protection of engineering possessions of the line.
3. Ensure that all relevant (including "line of route", "flank", "trapping", "overlap") infrastructure (points, Ground Frames, many level crossings, bridges, Patrolman Lock Outs etc.) is proved in the correct position and locked prior to authorising the train to proceed.
4. Provide adequate warning of train approach (other level crossings, trackside annunciation systems) such that people can clear the track sufficiently prior to the arrival of the train.
5. Ensure adequate separation between trains such that the following one gets adequate warning to brake to a stand in the event of the first train stopping.
6. Provide adequate information to the driver so that they may control (or preferably the signalling system itself enforce) train speed such that infrastructure speed restrictions (including junction turnouts, permanent and temporary speed restrictions, approach to buffer stops etc,) are respected.
7. Provide facilities to warn the driver of an emergency so that they may stop the train
8. Provide a "degraded mode" means of running trains in the event of a failure within the signalling system (e.g. noticeboards, rules, verbal communications with signaller, axle counter reset-restore, POSA).
9. Permit the efficient use of the railway infrastructure (maximum number of trains using it to full speed potential, ) by effective train regulation etc.
10. Provide train running information to a plethora of other systems associated with the running of the railway and interface to the public.
Your answer gave some of these, but not all were expressed clearly (very few actually stated a "purpose")
There were some definite "red herrings"- for example "maintainable and reliable" system is certainly important but it isn't a functional requirement of a signalling system (i.e. what is there FOR) but is a non-functional requirement (i.e. in this case HOW well it has to perform those functions).
Your answer was rather too short; my answer above is far too short and each heading needs a range of sub-bullets to give more examples and explanation but should give a suitable skeleton structure on which to build. What I have tried to do is ensure that the 10 items cover the full range and consider emergency / degraded/ abnormal modes of railway operations as well as normal use.
If I get a chance I'll review your answer in more detail later on this week
[quote pid='5878' dateline='1439753918']
Hi,
This is my first attempt at answering an IRSE question and I have attempted to answer a question on 'the principal purpose of a signalling system' and I'm just looking to get some advice guidance on;
Have I understood the question correctly
If so is the content enough to justify the marks for it
How could I improve my answer
Thanks
Mike
[/quote]
[*]
Mike,
You don't say (and I haven't investigated) the module in which asked but I assume mod3 given the section in which posted. The wording does sound a bit mod 7ish though and I would certainly answer it in terms of "functional requirements" but aligning to Signalling Principles. Hence I would say the 10 principal purposes would be:
1. Centralise control so the various points can rapidly be set to the required position for a movement and the driver then given the movement authority (conveying all necessary information about the movement to be made) so that the train may proceed without any undue delay.
2. Prevent conflicting movements from taking place simultaneously so as to provide safety at junctions and avoid the possibility of head on collisions occurring; a special case of this can be protection of engineering possessions of the line.
3. Ensure that all relevant (including "line of route", "flank", "trapping", "overlap") infrastructure (points, Ground Frames, many level crossings, bridges, Patrolman Lock Outs etc.) is proved in the correct position and locked prior to authorising the train to proceed.
4. Provide adequate warning of train approach (other level crossings, trackside annunciation systems) such that people can clear the track sufficiently prior to the arrival of the train.
5. Ensure adequate separation between trains such that the following one gets adequate warning to brake to a stand in the event of the first train stopping.
6. Provide adequate information to the driver so that they may control (or preferably the signalling system itself enforce) train speed such that infrastructure speed restrictions (including junction turnouts, permanent and temporary speed restrictions, approach to buffer stops etc,) are respected.
7. Provide facilities to warn the driver of an emergency so that they may stop the train
8. Provide a "degraded mode" means of running trains in the event of a failure within the signalling system (e.g. noticeboards, rules, verbal communications with signaller, axle counter reset-restore, POSA).
9. Permit the efficient use of the railway infrastructure (maximum number of trains using it to full speed potential, ) by effective train regulation etc.
10. Provide train running information to a plethora of other systems associated with the running of the railway and interface to the public.
Your answer gave some of these, but not all were expressed clearly (very few actually stated a "purpose")
There were some definite "red herrings"- for example "maintainable and reliable" system is certainly important but it isn't a functional requirement of a signalling system (i.e. what is there FOR) but is a non-functional requirement (i.e. in this case HOW well it has to perform those functions).
Your answer was rather too short; my answer above is far too short and each heading needs a range of sub-bullets to give more examples and explanation but should give a suitable skeleton structure on which to build. What I have tried to do is ensure that the 10 items cover the full range and consider emergency / degraded/ abnormal modes of railway operations as well as normal use.
If I get a chance I'll review your answer in more detail later on this week
PJW