203 Points Control Table

[interesting_signal]

My attempt at the 203 points control table is attached. Between this and the route control tables (still refining) I found it quite a mammoth task. I will wait for feedback before trying 211 points.

[PJW]

My attempt at the 203 points control table is attached. Between this and the route control tables (still refining) I found it quite a mammoth task. I will wait for feedback before trying 211 points.

I have approved the post itself to make it visible to all; as a moderator I can also see the attachment which I'll make visible next weekend- this is to give others the chance to post their attempts similarly.

I assume that by "mammoth task" that you meant that producing the CTs took you a very long time; perhaps at the moment as well as writing them out looking at the layout you are also simultaneously refreshing your memory by looking at course notes etc as you slowly work through them - yes this won't be quick but is an effective way to learn.

Overall you gave me pretty reasonable CTs- sometimes when people first give me something I don't know where to start commenting, but it is clear that you have put time and effort into these and I think that I can see the principal areas in which you need help; see attachment.

You are wise to seek feedback before launching into 211 points. First I'd like you to respond to the questions I have posed in the attachment containing my high level feedback and then I'll post your CTs annotated with more specific comments- I believe that others are also attempting them and this will also give them the chance to complete so that we can consider the various attempts together.

Certainly the exam is about speed and it is quite different doing a set of CTs with all the time in the world and when working against the clock. However for now don't worry re how long it is taking, you first need to get used to producing them to a reasonable standard and then gradually increase speed by practicing many different examples.

[interesting_signal]

Thanks for such detailed feedback. I've gone through the questions you posed, and the answers are attached. I already realise some things I've done wrong, and will try and correct these. I'll also be resubmitting control tables for 144A(S).

[PJW]

Thanks for such detailed feedback. I've gone through the questions you posed, and the answers are attached. I already realise some things I've done wrong, and will try and correct these. I'll also be resubmitting control tables for 144A(S).

I found your responses illuminating- perhaps some will act as a prod in the right direction for you to relook at some of your CTs, some confirmed my suspicions whereas others negated other working assumptions.

a) You do need to declare this in your exam answers; in your case it is looking like "Railtrack, mid 1990s, free wire Route Relay Interlocking".

a) & b) Your wider experience will be useful for the written questions but could perhaps confuse re the Control Tables slightly if you muddle practices- though so far this does not seem to be a problem. You have good source material but be aware that you will find some discrepencies between them, as all to slightly different standards. If you actually UNDERSTAND this is not a problem, but it can be tough in the initial learning phase.

c) see later

d) and e) Perfectly correct understanding- issue is that you didn't seem to be following it; I thought that it was this which was misunderstood but evidentally it is something else. Also be aware that we do often bracket expressions together when they span across various columns, often where there is a wide space then we link by filling the interim space with a dashed line: viz - - - - -
[Another comment re the maintained locking; ideally you should have horizontal lines dividing up into different levels the 3 associated boxes in order to keep the expressions together; sometimes where there were multiple routes the entries became a bit out of kilter with the list of tracks. It is a pain to do this in Word though, so perhaps use dashes to "join" and so it is obvious when you need to leave a line gap so that the two (or three if timer) column entries align correctly]

f) correct but doesn't match your CT

g) correct. You cannot actually tell which route / routes the "Auto" applies to. Actually generally only to one, but can be multiple. Probably would apply to both A(M) and A(W). Never to a © or (s).

h) correct but it MIGHT stop anywhere along the platform (e.g. if it is short train and the passenger station entrance is in the middle or one end of the platform to make it convenient- hence could stop short of DB track. Note that once train has come to stand it has no permission to restart unless the platform starting signal has been cleared or a verbal instruction from signaller.

i) similarly it may stop anywhere short of the first train; if due to join then will approach very close (3m) , stop and then when authorised move forward to couple. If not due to join will stop futher away if room permits. In this case given lengths. yes almost certainly on DC

j) Perhaps my question wa poorly worded; what I actually meant was "how does the MEANING of the aspect differ to the driver"

k) Good answer- practically never as it will always be one or the other; as I think you have realised yoour CT entry was a bit nonsensical in this respect. However there is an unusual scenario in which allowing a point movement to complete is a sensible control, but that is for the very advanced course!

l) Correct and I think you realise what I was getting at

m) Correct; the issue is that you need to learn to read IRSE diagrams re the assumed position of the clearance point. This sort of also explains item c); you know about foul but hadn't recognised the layout depiction for what it was.....
The trick is to look at which parallel running lines are at the nominal 6ft spacing (e.g. Up and Down Main) and then can assume that any IRJ which is closer to a point tip than opposite the other end of the crossover is bound to be foul- hence in the case of 207R this means both BM and EH. Where ther is reason to assume wider spacing (e.g. there is a platform separating the Down Loop and Up Loop) then IRJs opposite the switch toes of the other end of the crossover are bound to be well clear- for example I would assume that the BH/DA joint position would be clear of both and Up Loop (not that it matters since points are numbered 203A and 203B)
The answer to c) should be "ED locks 203 from going Reverse unless 205 is detected Normal since ED is a conditionally foul track circuit; also even if the joint had been at clearance there is also route locking after 115A"

n) Nothing needs to be said.

I certainly found this exchange useful in clarifying where you are coming from- being open about what you do and don't understand makes offering appropriate help much easier for me, so well done!

[interesting_signal]

j) what I actually meant was "how does the MEANING of the aspect differ to the driver"


The meaning is the same to the driver. 144 is only an independent shunt signal because there is no main signal at this point.

Does that answer the question?

m) Thanks for the explanation. That makes sense now. Yes, I didn't really know how to find the foul tracks for the points, or how to tell whether the joint was beyond the clearance point or not.

I'm in the middle of updating the control tables, and am trying 211 points too.

Thanks for your help!

[PJW]

j) what I actually meant was "how does the MEANING of the aspect differ to the driver"


The meaning is the same to the driver. 144 is only an independent shunt signal because there is no main signal at this point.

Does that answer the question?

m) Thanks for the explanation. That makes sense now. Yes, I didn't really know how to find the foul tracks for the points, or how to tell whether the joint was beyond the clearance point or not.

I'm in the middle of updating the control tables, and am trying 211 points too.

Thanks for your help!

A PL aspect means "proceed as far as the line is clear"; i.e. this is a promise to the driver that "the points are set and locked appropriately and that there is nothing coming towards you or will come in from the side- however there may be a train anywhere in front of you (either stationary or going in the same direction) and you must be able to stop before hitting it".
The difference is that when the PL is associated with a main aspect and when routed to a line which is defined to be "passenger permissive", (generally platforms at some major stations) then you may enter the occupied line with a passenger train. A GPL is only ever a shunting signal, not authorised by use by passenger trains and if routed into sidings, can only be taken as proving infrastructure on the runnning line (i.e. there could be points set incorrectly or opposing shunting movements taking place at low speed within the confines of the yard / siding. Sometimes it may prove more (e.g. the first set of handpoints, an aopposing move or perhaps even train detection is there is any); when doing a CT one should generally include in the aspect as much as is possible without preventing the signal showing proceed in circumstances when this may be required for an operational move that is needed.

[PJW]

I have now looked at Merlin's attempt as well.
again this was basically OK but
a) similarly missed the foul TC
b) missed off certain routes- probably just an oversight
c) similarly confused by the swinging overlap
d) failed to state on the CT itself for which set of points it was for!

So different random failures as one might expect but basically the same systematic ones- again the fact that swinging overlaps are difficult is not suprising.

Hence I am attaching both attempts for comparison; I have only marked up one (which happens to be Merlin's just because there is more space to be able to do so)

Have a look at this and ask anything that isn't clear

[merlin89]

Many thanks for your comments Peter; I attempted the CT before reading the thread to interesting_signal as I wanted to make my own mistakes first rather than get some clues where other people have gone wrong and to confirm my understanding. Got a better idea now about the swinging overlap just one point in the swinging overlap entry for 203 R-N in the column 'points set or free' why do we not include 205R?

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CT for points 211 submitted

[PJW]

Many thanks for your comments Peter; I attempted the CT before reading the thread to interesting_signal as I wanted to make my own mistakes first rather than get some clues where other people have gone wrong and to confirm my understanding. Got a better idea now about the swinging overlap just one point in the swinging overlap entry for 203 R-N in the column 'points set or free' why do we not include 205R?

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CT for points 211 submitted

My error: I wrote 203R when it should have been 205R; obviously 203 points cannot be checking 203 points!