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2008 mainline layout attempt
#21
Given your headway calculation outcomes, the main signals that you have placed appear to be consistent with the numbers. The fact that with those numbers you appear not to have ended up with any significant conflicts with fixed infrastructure would appear to be a blessing for the student and quite untypical of the normal layout!

The main comments on the layout are to with how you have used signals and their form rather than issues of spacing, braking and aspect sequences.

The remit was to allow trains to access the stabling siding with a train on the branch. At the moment to get a train into the siding, you would go from 10, 12 or 14 via the points to the branch, but you have to go behind 305 signal which takes you past 504 and hence on to the branch into the "one train working" section, hence you cannot meet the remit requirements.

305 signal is shown as being able to show R or G. What about routes into the bay and what if the next signal on the main line is R?

I was not entirely clear how your branch worked. It looks like some sort of one train working system, but I was not sure how you prove a train has arrived at station B and is then proved to have gone to the yard. At the other end, normal OTW systems are proved by a sequence of TC operation and a treadle, but no treadle is shown

For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.

You have numbered parallel signals with the same final digit. While this was common practice in the past, this is specifically not allowed.

You need to revise the meaning of a Limit of Shunt. These are for the end of shunt movement authority where the movement are in a direction that does not have any other signalled moves. There are no circumstances where you can pass an LOS in normal operation. With this in mind, how would you get a train through the run round loop (702) or out of the yard (713)?

In the yard, you have lots of motor points, but no track circuits. If the points are remotely operated, there needs to be some indication / control to prevent them being moved with a train on them.

Trap points. In the goods loops you have mentioned about trap points and used a symbol which I took to be traps and with what looks like a TC interrupter. You used a similar points symbol at 202 points in the yard but I was not clear whether you intended all of the points in the yard to be have trap points - you have n them with a sort of throw off but only numbered one end, so I assume they are not. This being the case, given the requirement to allow shunting in the yard while the branch is being used for passenger moves, how is this protected. Probably best to look at some trapping protection at the interface between the yard and the running line.

I am not clear about your method of working for the run round via the down main at E. You appear to be bringing the train into the loop, running the engine round and then propelling it onto the down main before setting off to the destination. what is the purpose of the "preset shunt signal" and the call on associated with 11 signal. I suspect that the examiners intention is that once the engine has run round, the train would set off in the up direction out of the loop. Although the arrows show running moves only in the down direction, I take this to mean that there are no signalled moves into the loop in the up direction. I do not consider setting off from the loop in the up direction to be in conflict with this.

Some more minor details: Some TC joints are missing (AJ/AK, BY/BZ); some point numbers missing; point numbering sequence and signal numbering sequences are usually kept separate - they are intermixed here; the GPLs in the siding appear to have been positioned to be parallel with the signals on the main line. This is not necessary and wastes a lot of valuable track in the siding; you'll need to check this one, but I think there is a requirement that if a route indicator is provided for shunt signals, all destinations need to be shown (ie 704 should probably have 5).
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#22
Thank you so much for your insights gentlemen, I have some follow up questions!

------------------------
PJW:
# overlaps just measured to be 180m beyond signal and placed without thought within S&C.

I thought i did place them with thought, but you just can't avoid swinging overlaps sometimes, or are you thinking about something else? I'm thinking at Station E signal 10 or 12 overlaps.
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Peter Martell:
Yes you are very astute in your obvservations, especially in my lack of understanding for OTW! You mentioned that track circuit sequencing and Treadle is required, is this all I would need to draw on the plan, or do I need further explanatory notes/calcs (once i find out how to do it of course) - where can i find out about this?

Also I have used SI's instead of JI's at the end of a platford for example, where the train would start from stationary - have I wrongly assumed the use of SI's for this application? When do you use SI's and when do you use JI's?

Regarding my Trap points in the freight yard A, only my 202 are traps, as the rest of the points act as trap points anyway due to their normal position? the reason iwanted to make 202 traps is because it prevents a head on runaway train collision..

Regarding the runaround signalling at the down goods loop, the reason i ran around with the signals 603 and 605 is because of those arrows that suggest they only want trains to move off in that direction? my preset shunt and call on signal is a mistake.

All other notes that you both have commented are silly mistakes, which I will hopefully correct with practise (this is my 2nd attempt at the layout).

Thanks again,

Priyank
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#23
(23-09-2009, 07:46 PM)priyman Wrote: ------------------------
PJW:
# overlaps just measured to be 180m beyond signal and placed without thought within S&C.

I thought i did place them with thought, but you just can't avoid swinging overlaps sometimes, or are you thinking about something else? I'm thinking at Station E signal 10 or 12 overlaps.
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Priyank

The overlap beyond sig 10 results in the AR/AQ joint being foul of 103R; therfore AQ must lock these points normal so delays the time when a route can be set from bay platform to branch after a train on the Up Main. If you had placed the joint opposite 103C then it would have been at clearance, resulting in earlier release of locking since AQ would not need to lock- the O/L would be better at 210m from signal 10.
If however the permissible speed had been lower then you may have been able to justify a shorter, reduced, overlap at the AS/AT joint.


Similarly joint BS/BT is foul; this means that if 103 are Reverse then the overlap beyond signal12 is not available and therefore a train would have to be held at 166 rather than being permitted to enter the station. In this case I'd have put the overlap at the BS/BR joint and additionally defined a "Restricted" overlap [ROL] as far beyond signal 12 as I could but just short of the unnumbered crossover to the Branch. This would need BT to be split into two separate tracks and 166 given a Warning class route.

The message is THINK about the significance of the overlap positions to interlocking (yes it is module 2 but apply what you know about Control tables from module 3)- don't just automatically measure the standard 180m and plonk down an overlap symbol.
PJW
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#24
(22-09-2009, 09:58 AM)Peter Wrote: For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.

Could you give a reference for the use of PLJI into a bay? I have looked through the group standards GK/RT 0031 and 0032 and cant find one. I would normally place an SI here as custom and practice but did not know that the use of PLJI into a bay was outlawed.
Thanks
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#25
(05-12-2009, 01:26 PM)MarkN Wrote:
(22-09-2009, 09:58 AM)Peter Wrote: For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.

Could you give a reference for the use of PLJI into a bay? I have looked through the group standards GK/RT 0031 and 0032 and cant find one. I would normally place an SI here as custom and practice but did not know that the use of PLJI into a bay was outlawed.
Thanks

Very good point. I cannot find it in the standards, but it is something that stuck in my mind from IST or the like, but now I have come to look for it..... I'll check with some older and wiser people and come back to you.
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#26
(05-12-2009, 10:11 PM)Peter Wrote:
(05-12-2009, 01:26 PM)MarkN Wrote:
(22-09-2009, 09:58 AM)Peter Wrote: For 10 and 12 signals, you have given them SIs rather than PLJIs. Although these are MAR for the turnout route, I would normally expect them to be PLJIs for such a signal. Conversely, 7 and 157 have PLJI for all routes. This is a problem for the route into the bay as this is not allowed.

Could you give a reference for the use of PLJI into a bay? I have looked through the group standards GK/RT 0031 and 0032 and cant find one. I would normally place an SI here as custom and practice but did not know that the use of PLJI into a bay was outlawed.
Thanks

Very good point. I cannot find it in the standards, but it is something that stuck in my mind from IST or the like, but now I have come to look for it..... I'll check with some older and wiser people and come back to you.

It is something that has come in relatively recently with NR's insturction NR/L2/SIG/19609. This states in section 6.1:

A PLJI shall be used in association with main aspects where more than one route exists except where an SI is required due to one of the following conditions:-
a) The route destination is a terminal platform. In cases where there are no through routes from the junction signal an indication shall be provided for all routes.
b) etc


You will find that there are plenty of places where there is a PLJI into a bay and I don't see any particular problem with it. I suppose the argument is that it is unlikely that the turnout will be particularly fast and in a multi parallel line to multiple platforms at a through station it can be confusing to the driver that the bay platform could be a PLJI pos1 on one line, PLJI pos2 from the adjacent line and PLJI pos3 from the next.

Flasshing aspects to a PLJI into a bay platform was always banned (but certainly High Wycombe did feature this on the TOC's insistence when MAS was installed in the early 1990s- I wouldn't be completely suprised to find that it is still like that- since the line has ATP then I suppose that any risk is mitigated.
Be aware that some signalling "rules" change; partly it is "preferential engineering", partly because an incident has occurred, sometimes the environment changes or is different locally to nationally. As far as I know a PLJI into a terminal platform would not require a non-compliance to a Railway Group Standard (i.e. such an indication is compatible with the Rule Book etc); however it isn't good practice to provide one.
PJW
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#27
FYI
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