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Module 3 Answers
#3
(04-05-2010, 09:10 AM)Andrew Lockyear Wrote: My answers to Module 3 are attached

You should use your first sheet that lists some $ refs also to define the standards which you are following.
In particular I think you should explain here various assumptions e.g.
re whether certain track joints are at clearance,
the way routes read (418C could be via 249R or indeed via 249N
whether shunt routes have overlaps

Particularly since you have chosen not to signal the swnging overlaps that the plan depicts, you should draw this to attention "up-front".

Also you have done something pretty unconventional re providing a single Control Table for 365A(M/W/C) and have annotated certain entries to which classes they apply, but in the absence of annotation then an entry applies to all. I know why you took this approach, but it doesn't make them easy to read or to mark- the least you can do is take a little time to explain your presentation rather than expect the examiner to work it out, particularly when you are simply adding a C or W to an entry!

Also suggest you should define abbrieviations such as SRL.
------------------------------------------------------------------------
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Point Control Tables

1. No value in the disconnect facility box and entry.

2. Foul Tracks!
235RtoN needs to be locked by BT
I also suggest 235NtoR needs to be locked by [BU or 236N]
Similarly AF, DR and BT all appear to be conditionally foul TCs for 236 and therefre should be included in tthe relevant track circuit dead locking.

3. This has implications also for the extent of the route locking which needs to be imposed by relevant routes.

4. 235 are trailing points within the overlap for 412A(M) as well as 416A(M)- the fact ou got one and not the other looks like careless oversight.

5. Overlap route locking needs to list ALL tracks between the entrance signal and the exit signal, but the SRL on both the platform tracks should be overriden if either of them has been occupied for the relevant time to prove train at stand on their combined length. Route locking in the overlap is only required if the track is not itself a dead-locking track and any such locking should not be overidden by platform track(s) occupied for time.
e.g. for locking on 235 after 416A(M)
DH, DJ, DK, [DL, DN or (DL or DN) occ for 45s], DP
However this expression doesn't fit easily into the standard column layout so therefore generally written:
TCs clear after route used_______or TC occ for t
DP, DH, DJ, DK [DL, DN ...............(DL or DN) 45]

6. Route locking on 235 after 378C(M) is BT BU (i.e. the foul track) rather than BT DR (since the route doesn't read that way and this is locking holding 235 in N)

7. You seemed to overlook 365 completely re 235 points.

8. Even if you are not going to have NR style swinging overlaps, then I don't think that you can simply ignore that there are alternative overlaps beyond 378 towards the Up Main and also towards the Up Branch- it'd be very restrictive only to have the one. A lot of railways would permit the signaller to select one of the possible overlaps (e.g. by keying the facing points prior to route setting) and then locking it until trin has passsed or alternatively been timed to stand.

9. 236 points. You seem to have missed 265 again; similarly 351! It is perhaps arguable whether 351A(M/W/C) should set and lock 236R as switch diamonds tend not to provide useful flank but I think I'd include. Certainly 351B(M/C) reads directly over them so that has got to be an omission.

10. Unclear why you claim 418B(S) should lock 236 yet 414B(S) should not
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PJW
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Messages In This Thread
Module 3 Answers - by Andrew Lockyear - 04-05-2010, 09:10 AM
RE: Mod 3 Q2 Answer - by PJW - 31-05-2010, 01:02 PM
Module 3 Control Tables: General and Points - by PJW - 01-06-2010, 09:39 PM
Module 3 Control Tables: Routes - by PJW - 03-06-2010, 08:21 PM

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