2002 Mainline Layout answer

[PJW]

As a late addition to the Study Pack (will be included for the 2009 edition) I have produced a suggested answer for 2002 together with a commentary explaining the rationale for some of the decisions and sometimes higjhlighting areas of improvement that have become apparent in retrospect.

This was primarily undertaken in connection with the London Study Group but is placed here so that others are able to share the information. Note that it is not complete in that no route boxes have been provided and although the key track circuit divisions have been shown this is not necessarily the totality and therefore the sections have not yet been individually identified. The primary purpose of the exercise was to concentrate on the provision of signals to meet the specified requirements.

Separate attachments are provided for the text and the various portions of the layout; I hope I have made a reasonable compromise re resolution and file size. (Note despite the nomenclature there are corectly only 4 portions of layout).

PJW

[adikarina]

Peter,
Thanks for the attached examples and comments. Found them useful to read and understand. I was wondering if you have something similar for the Rapid Transit Layout. I am sure it would be useful for all LU candidates. I have been searching high and low for such an exapmle.
Thanks
Regards
Aditi

As a late addition to the Study Pack (will be included for the 2009 edition) I have produced a suggest answer for 2002 together with a commentary explaining the rationale for some of the decisions and sometimes higjhlighting areas of improvement that have become apparent in retrospect.

This was primarily undertaken in connection with the London Study Group but is placed here so that others are able to share the information. Note that it is not complete in that no route boxes have been provided and although the key track circuit divisions have been shown this is not necessarily the totality and therefore the sections have not yet been individually identified. The primary purpose of the exercise was to concentrate on the provision of signals to meet the specified requirements.

Separate attachments are provided for the text and the various portions of the layout; I hope I have made a reasonable compromise re resolution and file size. (Note despite the nomenclature there are corectly only 4 portions of layout).

PJW

[PJW]

I am afraid not; you and me both.
The Study Pack certainly needs much more Metro content but unfortunately it is not within my competence to add this myself. Peter Clifford did give me some stuff including the Appendix M Step-by-step generic guide that is included within the 2008 edition, but just did no have the time to be able to do for the Metro layouts the same sort of overall commentary that I did for the Mainline ones, let alone something as detailed as I have now done for 2000, 2002 and 2006.

Certainly we are looking for a volunteer from the Metro community who would be able to do this for the 2009 edition (and indeed could be distributed like this one if done prior) VOLUNTEERS PLEASE; Metro students try to twist a few arms of likely victims that might be press-ganged!

PJW

Peter,
Thanks for the attached examples and comments. Found them useful to read and understand. I was wondering if you have something similar for the Rapid Transit Layout. I am sure it would be useful for all LU candidates. I have been searching high and low for such an exapmle.
Thanks
Regards
Aditi

PJW

[/quote]

[savitha kandasamy]

Hi PJW,
with reference to your 2002 solved layout, I have one query. For upbranch, AHBC has a treadle placed near to SIP(40 sec).. My understanding is that, if a signal happens to be placed within the striking distance, the signal is approach released (delayed clearance control). But I am not able to understand the need for one more treadle near signal G38. Kindly clarify.

[PJW]

Haven't got access right now to my plan, so will respond later re detail.

However the treadles needed for an AHBC are:
1. For the outer strike in, which as you say could need to be inhibited if there is a signal within this area that then could require to have delayed clearance applied.
2. To detect a SPAD (to back-up the TC occupation) at such a signal
3. Treadles either side of the road crossing in order to determine directionality of the train and to rasie the crossing afterwards
4. Strike-in for a "wrong direction" train (as per 1 but generally placed at lesser distance to reflect the lower speed for moves in the abnormal direction)

Hi PJW,
with reference to your 2002 solved layout, I have one query. For upbranch, AHBC has a treadle placed near to SIP(40 sec).. My understanding is that, if a signal happens to be placed within the striking distance, the signal is approach released (delayed clearance control). But I am not able to understand the need for one more treadle near signal G38. Kindly clarify.

[PJW]

Yes having now had a chance to look at it, the directional treadles just beyond G38 are to initiate the crossing if the outer strike-in had been inhibited by the signal being At Red And Free of Approach locking.

If this signal was later able to be cleared, then the crossing would be initiated immediately but where this could lead to the train arriving at the road too soon, then the actual aspect displayed to the driver would be delayed until this risk prevented.

However if this signal could not be cleared and therefore the driver needs to be verbally authorised to pass at danger (or in the event of a SPAD) then the crossing should immediately display alternate flashing red lights and give audible warning; the treadles at the signal are one of the diverse means of initiating this.

I also notice when I produced this layout that I positioned the strike-in for a 30sec strike-in rather than the 40sec which is needed for a double line crossing in also to give the 10sec "Another train Coming" feature. I did though draw attention to this error by placing a note to that effect against the opposition line's strike-in. I honestly cannot now remember whether this was a genuine mistake on my part, or actually deliberately included in order to show the sort of thing which happens in exam conditions and the way to get over it- in general there is not the time to rub lots out and attempt to correct, so making the examiner that you are aware and know how to rectify is often the better use of time and is far less prone to error and looking very confusing.

Haven't got access right now to my plan, so will respond later re detail.

However the treadles needed for an AHBC are:
1. For the outer strike in, which as you say could need to be inhibited if there is a signal within this area that then could require to have delayed clearance applied.
2. To detect a SPAD (to back-up the TC occupation) at such a signal
3. Treadles either side of the road crossing in order to determine directionality of the train and to raise the crossing afterwards
4. Strike-in for a "wrong direction" train (as per 1 but generally placed at lesser distance to reflect the lower speed for moves in the abnormal direction)

Hi PJW,
with reference to your 2002 solved layout, I have one query. For upbranch, AHBC has a treadle placed near to SIP(40 sec).. My understanding is that, if a signal happens to be placed within the striking distance, the signal is approach released (delayed clearance control). But I am not able to understand the need for one more treadle near signal G38. Kindly clarify.

[laz07]

Hi,

Would it possible for anyone to post a blank 2002 layout on here?

Many Thanks

[asrisaku]

Hi Laz07

Please find it below.

Best regards, Arnut

[laz07]

Thanks!