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+----- Thread: 2008 - CT (/showthread.php?tid=240)
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2008 - CT - sugavanam nagarajan - 13-06-2009
Kindly review the control table for 2008.I have tried it with the format already used by the forum member.
This is my first attempt on CT in UK practice,I would like to improve my knowledge from your comments.
-Sugavanam
RE: 2008 - CT - PJW - 14-06-2009
The first thing to say is that these are very good; if this is really your first attempt at UK style Control Tables then the UK student population should be extremely worried as you are demonstrating how badly they need to pull their socks up and raise their game.
1. A small point re the headings (I haven
RE: 2008 - CT - sugavanam nagarajan - 15-06-2009
Thank you for your detailed comments and encourgement.I have done this based on the knowledge gained from your comments previously posted in the forum.But still i want to gain more technics from you.
1.If treadle operated condition is proved for call on move, then time delay(approach control) not required is't correct?
2.Is it necessary to provide LWR for all shunt movement eventhough not specified in route table.
3.The note "Permissive working permitted in platform lines" not given in the layout, So i have assumed that "No permissive move".
4.How to mention overrun protection for the route 161A(M)?
5.For the route 161A(M) comprehensive approach locking:
FC,FD,(FE,FG OR 244 R),(FH OR 244R)--------149 ARAFOAL.
6.How to find the time dealy for junction signal having MAR, ROL less than 55m-from the notes of yours re time values for IRSE exam purposes.
7.Explain the principle behind indirect opposing locking and how to find?
[124B(M)-135B(s) is indirectly opposing route]
-Sugavanam
RE: 2008 - CT - PJW - 15-06-2009
(15-06-2009, 09:35 AM)sugavanam nagarajan Wrote: Thank you for your detailed comments and encourgement.I have done this based on the knowledge gained from your comments previously posted in the forum.But still i want to gain more technics from you.
1.If treadle operated condition is proved for call on move, then time delay(approach control) not required is't correct?
2.Is it necessary to provide LWR for all shunt movement eventhough not specified in route table.
3.The note "Permissive working permitted in platform lines" not given in the layout, So I have assumed that "No permissive move".
4.How to mention overrun protection for the route 161A(M)?
5.For the route 161A(M) comprehensive approach locking:
FC,FD,(FE,FG OR 244 R),(FH OR 244R)--------149 ARAFOAL.
6.How to find the time delay for junction signal having MAR, ROL less than 55m-from the notes of yours re time values for IRSE exam purposes.
7.Explain the principle behind indirect opposing locking and how to find?
[124B(M)-135B(s) is indirectly opposing route]
-Sugavanam
I thought you must have had a good teacher !
1. I have never known a release to be after a time following treadle operation. Whereas a track joint being provided for othe purposes may not be in the right place, if a treadle is to be provided then it can be positioned precisely where needed. Treadles are expensive items requiring regular maintenance (it may be different as and when we get an electronic version approved for use), so tend only to use nowadays when there is no realistic alternative- hence use for approach release at all is now rare, tend to be used mainly for level crossings.
2. To UK NR standards, then yes LWR is provided for GPLs and generally for shunt moves associated with main aspects. Do so in the exam.
3. I now understand your logic and confusion. When it is said that permissive working either is or is not permitted in platform lines, what it actually means is whether the permissive operation of passenger trains is permitted (this is generally only nowadays permitted when two separate multiple unit trains are to join up so can proceed with onl;y one driver and inceasing capacity by only needing the one "train path"; however there are still some places where it is permitted that a second train can enter to use one portion of a platform whilst the other end has a separate train in it- primarly there are insufficient platforms and it is a way of using a long platform for two short trains without having to provide mid platform signals). However the ability to use a shunt signal to signal a locomotive onto coaches or to strengthen a mltiple unit train with extra unit from the sidings etc. is always regarded as permitted and yes, to be of use it would have to be permissive. It is the shorthand "permissive" which strictly should be "passenger permissive" that has created confusion; I am afraid that you just have to get used to what is really meant. Of course if you had experience of the operational use of such a layout then there wouldn't have been the confusion. At least the advantage of this website over a textbook is that you can ask such questions!
4. I'd write it in the Remarks column."Replaced by SPAD at 157 until BL clear, replaced by SPAD at 159 until CJ clear, replaced by SPAD at 164 until CF clear". Look for those signals from which a train could trail into the route (i.e. converge with it in either the same or the opposing direction), but omit any where the point calling of the CT's route would prevent- in this case 256N protects from a SPAD at 162. The track to specify is the one that is furthest from the protecting signal which is not already listed as being a track required clear within the CT's signal's aspect. Hence if doing the CT for route 156A(M) then wouldn't need to worry about SPAD at 154 or 152 as immediately the SPAD occurs CN or FE become occupied and these are proved clear anyway. Don't need to worry about SPAD at 124 as 236N is a requirement and thus there is flank point protection; however if the overlap had been EG onth then would have had to worry about "SPAD at 124 until EH clear" i.e once a SPAD has been detected at 124 then occupancy of DG, DH, DJ or EH would maintain 156 at danger.
5. Until signal ARAFOAL and tracks clear:
FC, FD, FE [(CP or 242N), FG or 244R] --------
FH --------or 149 ARAFOAL or 244R
Note the nested brackets - different types makes it more readible. The 244R condition applies to all within the [ ] whereas the 242N condition applies to those within the (), i.e. CP. If there had been more tracks beyond 149, then these would have been listed next to FG.
The first line of entry relates to the "first section in rear" and for 3 aspect signals there will be a second line of those rtracks conditioned out by a signal ARAFOAL. For 4 aspect sequence only, there would be a third line of entry and this would be conditioned out by either the first or second signals ARAFOAL.
Note that 149 can be cleared for a different route, then that route also needs to be conditrioned out by point lie (or alternatively you could state 149B ARAFOAL).
In reality it wouldn't be worth putting CP in the lookback at all since the approach in this direction is just from a GPL so no aspect sequence nvolved; I only included to show you what to do had this been a main signal.
6. Please rephrase the question as I don't completely follow what you are after. You certainly would never have a ROL less than 45m and nowadays less than 60m is unlikely (TPWS effectiveness even at very slow speed). The approach release for the shortest ROL is identical to that of a PL; i.e. train very nearly at a complete stand- the longer the ROL the earlier the release as a slightly higher speed approach is appropriate. Note that approach release for a Warning route is not referred to as MAR- this term reserved for approach release associated with junction signalling.
7. Yes you seem to understand it. For 124B(M) the direct opposing routes are 131B(S) and152A(M) and 164A(M/C) and 166A(S) - on the assumption that the overlap beyond 161 is only via 255R at the end of CH. These are directly opposing since they do not require any conflicting point positions. The indirect opposing routes are from the signals parallel to these; i.e. 135B(S), 156A(M), 162A(S). Whereas 135B(S) requires 237N and thus it INITIALLY does not oppose 124B(M) (i.e. it is the point locking which prevents the conflicting route from setting), once a train hascleared EG and is standing on EH, DJ, DH then the locking on 237 is released and thus they can be swung R. By this time the train from 135 is therefore indistinguishable from one that could have come from 131; therefore opposing locking is needed in just the same manner. To find opposing locking look for the "exit" of the routes in the opposite direction along the line as for the CT's route. Check EVERY signal that can read to that as a destination- regard them all as potential candidates for opposing locking, if you find one then look for all the "parallel" signals. Then remember to keep looking for routes that are further away but still overlap part of the CT's route and if you find one then look for all its "parallel signals"
RE: 2008 - CT - alexgoei - 14-07-2009
Hello Sugavanam,
Hope you found the column format useful.
I must say here that I did not get the format right the first time. It somewhat evolved with practice on past exam papers and comments on my answers by PJW. I think you will find some changes between the earlier tables on this website compared to the later ones. I then used it for last years exams. Hope this gives candidates the confidence to use them.
For me this format uses the least possible time to prepare in the exam compared to the Network Rail table (the 11202?).
One question I have been asked with respect to making copies during the exam and would like to post it here is that you need only to prepare one hand written copy. Use the A3 size sheet provided for the exams. You can then photocopy the rest that you need. Typically up to 3 copies is generally sufficient.
I have used a 2B mechanical pencil for the exams. As the entries are closely spaced, having an eraser plate (like those use by draftsman) will be very useful for making amendments.
Hope this is useful.
RE: 2008 - CT - sugavanam nagarajan - 14-07-2009
Thank you for your tips.
I am going to use the same format with modifications pointed out by PJW
-Sugavanam
RE: 2008 - CT - greensky52 - 07-07-2010
Comparing my work to his, I also have some confusions:
1. 147B(S): requires TC clear, do not requires CJ and CH clear? My answer is "CP, CN CL, CK, CJ, CH". In the opposing route locking, it indeed usually does not require overlap TC clear for the shunt route.
2. 147B(S): for thr opposing route 164B©, my answer for 164B© is"CF,CG,CH,CJ,CK,CL clear or CKorCL occ for 30s". Am I wrong?
3. 124B(M): 166A(S) and 164A(M/C) do not have common overlap. So why should require them as opposing route locking?
4. 161A(M): Why the opposing route locking require 149B©? I am confused about which situation it belongs to?
(14-07-2009, 06:32 AM)alexgoei Wrote: Hello Sugavanam,
Hope you found the column format useful.
I must say here that I did not get the format right the first time. It somewhat evolved with practice on past exam papers and comments on my answers by PJW. I think you will find some changes between the earlier tables on this website compared to the later ones. I then used it for last years exams. Hope this gives candidates the confidence to use them.
For me this format uses the least possible time to prepare in the exam compared to the Network Rail table (the 11202?).
One question I have been asked with respect to making copies during the exam and would like to post it here is that you need only to prepare one hand written copy. Use the A3 size sheet provided for the exams. You can then photocopy the rest that you need. Typically up to 3 copies is generally sufficient.
I have used a 2B mechanical pencil for the exams. As the entries are closely spaced, having an eraser plate (like those use by draftsman) will be very useful for making amendments.
Hope this is useful.
RE: 2008 - CT - PJW - 07-07-2010
(07-07-2010, 06:19 AM)greensky52 Wrote: Comparing my work to his, I also have some confusions:Basically you need to think what the route is FOR. If you assume that it is to shunt an entire train that arrived in the Platform Loop from the north curve and now needs to be put in the Up platform, then proving all tracks clear in the route is tenable. Therefore to modern standards you'd be right to include CJ and CK as well, particularly as plan shows this as explicitly a shunt overlap,; however be aware that until a few years ago, overlaps for shunt routes would not have been proved.
1. 147B(S): requires TC clear, do not requires CJ and CH clear? My answer is "CP, CN CL, CK, CJ, CH". In the opposing route locking, it indeed usually does not require overlap TC clear for the shunt route.
However if you think that the route may at least sometimes be used to take a short formation train, perhaps originally from the Up siding and run via the Platform Loop onto the Up Main, in order to set it back onto a short train already in the Up Platform then the omission of CK, and possibly also CL ,would be essential; proving an overlap clear in such a situation doesn't make much sense.
Generally therefore what to the signaller a shunt route is often within the interlocking itself two separate ones:
a) a non-permissive (selected by CL and CK clear) which comes with an overlap as you have shown, thus getting maximum safety when thi is possible
b) a permissive (selected by CL or CK occupied) where only the minimum number of tracks are proved clear, thus enabling its use to join trains together and gaining operational flexibility when it is needed.
So you need to look at the layout, decide how it would be operated from what clues there are around, state an assumption that justifies the locking you provide. To be honest in this case I am struggling to see much need for the route at all; the main use could be to cross a train that has terminated in the Down Platform onto the Up to await time to return on the Up Main. However if only a short time then have running sgnal 156 for that; if a longer time and needed to clear the Down for other traffic, then use of 157 and the set back shunt at that end of the station to do this move would seem the preferable option.
So the simple answer is that you are right IF you stated that you foresee no need to use the route to join vehicles in the Up Platform
For your opposing route locking comment I interpret that you mean that the locking that this route IMPOSES on the up direction routes. Historically shunt routes didn't have overlaps and therefore you are right, but where overlaps are provided at aspect level I'd certainly expect in the opposing route locking. Indeed could well have the tracks included in the opposing locking even if not proved by the signal's aspect; I would interpret the plan in this case as meaning that they ought t be included (unless you state your railway's standards don't provide any form of overlap for shunts and therefore you will no be precisely following the plan in this regard)
Quote:2. 147B(S):
for the opposing route 164B(C ), my answer for 164B(C ) is "CF,CG,CH,CJ,[CK,CL clear or 9CKorCL occ for 30s0]".
Am I wrong?
147B(S) needs to ensure that any train previously authorised to take routes from 164B(S) has either:
a) gone away completely, or
b) has timed to a stand in the platform so that further vehicles can be safely added to a stationary train. This does of course is only valid if you are not proving all tracks clear in the shunt route's aspect level; otherwise it it is effectively as per a main route and therefore only option a is applicable. The route should NOT set if the aspect isn't ever going to clear.
This is one reason why I would recommend adopting the older standards for shunt routes; many of us including the IRSE examiners have been around for a few years and were brought up with the older standards and therefore initially expect them. Adopting modern standards means that there is little real difference between PL and main aspect moves, so an opportunity for the student to demonstrate their knowledge is lost.
Certainly you must be consistent; the inclusion of "or occupied for time" in the opposing locking for a shunt route requiring the same tracks clear indicates that the candidate really doesn't understand what they are doing!
It is however perfectly reasonable to set and lock an overlap at the route setting level which prevents opposing / conflicting moves in it but not actually depmand those points detected and the relevant tracks within the overlap clear within the aspect proving level. This way you get almost all of the safety in the event of a SPAD at the exit signal (though obviously inevitably with the equivalent loss of layout flexibility in operation that this implies) whilst minimising the chance of a failure preventing the aspect clearing.
If you are giving shunts overlaps then the opposing route locking should include proof that FE has been cleared ( note that this locking isn't by passed by occupancy for time of FD/FC) even for an opposing shunt route whose aspect does not prove those track clear.
Quote:3. 124B(M): 166A(S) and 164A(M/C) do not have common overlap. So why should require them as opposing route locking?
124B(M) only reads to 149 and you are right that its overlap only includes FG. Therefore it is permissible to set routes from 166A simultaneously as the overlap does only include FE. Hence wouldn't need opposing locking between these, so you are correct.
Quote:4. 161A(M): Why the opposing route locking require 149B©? I am confused about which situation it belongs to?
161A(M): actually this isn't opposing route locking but GK/RT0044 locking sometimes (but actually erronously though the name has now stuck!) called "Huddersfield". The intention of this is that if a train entering a platform has been given a PL aspect because a call-on route has been set, then the first train already in the platform is then deliberately trapped there; hence the second train will actually find the platform occupied.
a) The call-on route requires that all routes from the platform exit signal are not set.
b) The routes from the platform signal require that the call-on route isn't set and any train on that route has reached the platform.
Actually there is often somewhat greater complexity than this re attempting to prove that it is really at a stand, which can be very involved given that there can be a range of scenarios re which tracks were initially occupied or clear depending upon the length of the first train already in the platform and the second one joining, or indeed it could even be a third one....... In my view this has just got silly in the real world and is certainly FAR TOO FAR for the IRSE exam. Potentially you could adopt practices that don't have this locking at all; I think I would recommend putting something in, but keeping it simple and to the essence as I have described above.
RE: 2008 - CT - greensky52 - 08-07-2010
Item 2, 3, 4 are noted. Thank you a lot.
Referring to item 1, I am not sure I have got your point. In short, do you mean it should be decide by the actual situation of shunt route?
If the shunt route is for a pemissive movement, it is no need to consider the overlap. Such as shunting a train to couple with another one which stop in the platform?
If it is an unpermissive movement, overlap have to be considered for safety. Such as wrong direction movement?
Also another question, I did not find much about the approach locking in Study Pack. So I checked the British Rail Control Table.
It is said "Shunt signal only become approach locked once a proceed aspect has been displayed and any berth track within 50 yards has been occupied. In the absence of a berth track, the siganl is approach locked when clear." So is it only in a shunt route, approach locked applies for signal when signal clear or TC occ? And does it require the berth track shorter than 50yard(45m)? There is only one case in that book, so I can hardly judge my reference is right or wrong.
I refer to the column in CT as attached.
RE: 2008 - CT - PJW - 08-07-2010
(08-07-2010, 09:11 AM)greensky52 Wrote: Referring to item 1, I am not sure I have got your point. In short, do you mean it should be decide by the actual situation of shunt route?
If the shunt route is for a pemissive movement, it is no need to consider the overlap. Such as shunting a train to couple with another one which stop in the platform?
If it is an unpermissive movement, overlap have to be considered for safety. Such as wrong direction movement?
In short Yes, there is no one answer for shunt routes-
a) sometimes they prove all tracks clear and have overlaps (just as if main routes),
b) sometimes they prove all tracks clear in route itself but not have any overlaps at all,
c) sometimes they prove all tracks clear in the route itself but not in the overlap yet still lock an overlap
d) sometimes they prove only some tracks clear in the route itself and would therefore have no overlap at all.
The appropriate option depends on both:
1) the standards being adopted for your Control Tables
2) the specific layout and the operational use of the route.
Modern NR practice would be to use option a) whenever possible but use option c) as non-preferred option if need to use to join vehicles or even option d) if essential for flexibility.
Older practice would be use option d) almost always but use option b) if the move was effectively a running move from a PL signal (rather than a true shunting move). Option c) woul;d be used if a specific safety risk re an overrun existed.
If you want a simplistic answer for IRSE exam then I suggest best to default to use option d), but if the layout is definitely indicating that there are specific shunt overlaps then use option c)
Quote:Also another question, I did not find much about the approach locking in Study Pack. So I checked the British Rail Control Table.
It is said "Shunt signal only become approach locked once a proceed aspect has been displayed and any berth track within 50 yards has been occupied. In the absence of a berth track, the sigala is approach locked when cleared."
So is it only in a shunt route, approach locked applies for signal when signal clear or TC occ?
And does it require the berth track shorter than 50yard (45m)? There is only one case in that book, so I can hardly judge my reference is right or wrong.
I refer to the column in CT as attached.
In general signals are approach locked when the signal clears.
For a main signal, occasionally it is worth providing "comprehensive approach locking" such that the locking is only actually imposed (or can be immediately released) if all the tracks are clear back to the sighting point of the furthest signal which changes aspect when signal concerned is replaced to danger. However it can be expensive to provide and takes time to test, so only provide where particularly useful.
Conversely a GPL signal is only visible for a short distance and the maximum speed of train approaching a GPL is only 15mph. Therefore comprehensive A/L is "always" provided (since it is cheap and simple).
Hence if there is a berth track which is at least 45m long, then this is the one track which is listed; in the odd case that the first track is less than this then would need to include the second track back as well. If the only track is less than 45m or there is no berth TC at all, then comprehensive cannot be provided, so no tracks are listed and th entry is "when cleared"