2010 Layout

[PJW]

During the time that the website was disabled whilst the exam was being undertaken at locations around the world, I received the following:

Quote:Dear Sir,

I have give the Mod-2 paper this year but i found that non-stopping headway required in the paper was give 600 sec. and after doing calculation the Dg-r distance comes nearly 20000 mtrs. which was too much as compared to Braking distance that comes nearly around 1000 mtrs. Also, with this calculations stopping headway(required is 3.5 min but theoritically it is comming 3 min 45 sec) can-not be achived. Is every thing right in the paper.
Not only me everyone in Hyderabad(India) faces the same problem. I do-not know whom to approach so i am wrieting to you as you were always helpfull to us.
Waiting for reply.

Amit Kumar Srivastava

[PJW]

During the time that the website was disabled whilst the exam was being undertaken at locations around the world, I received the following:

Quote:Hello Peter,

I suppose its quite OK to tell you about this morning's Module 2 layout as the exams in the UK must well be underway by now.

Station D was a station with four tracks of which two inner ones lead to a turnback siding offest to one side of the Main while the other two straddled the Up and Down Main. Coupling and Uncoupling of trains at Platforms 1 & 2 were required, so a must for call-ons since the depot was just before the station.

Near Station D was a depot with two sidings, a train wash track, headshunt and reception track. I suppose the way to treat the depot was to treat it like a Freight depot.

As I had expected, the layout had a level crossing. The level crossing was located just before Station D and it had 300 vehicles per peak hour so moderately busy I think. I decided to go for Manual Barrier Crossing which I think is the easiest to do, but forgot to mention monitored by CCTV remotely although the symbols correspond with the srtandards used by Network Rail. Put in a short justification for MCB.

For non stopping which was for trains every 10 minutes, two aspect with distant signals was OK but the determinant was really the stopping.

No contingency for headway required - so even with stopping three aspect will do the job although as usual four aspect would be more suitable given the numerous junctions there. Headway required was 3.5 mins.

I made an error which cost me some rework and time when computing the stopping; for the distance between signals I made the mistake of using the distance for the headway of 120 km/h (1115 metres) instead of the permitted of 140 km/h (of 1515 metres) but discovered it in time before I started putting down the signals.

So assumptions, non stopping and stopping were all there like in the practices posted on the forum.

I managed to put in the signals for one direction and was able to show transition from 4 to 3 aspect but did not have time to name the track circuits and put in the signals for the rest of the plain line layout. Most of my effort was concentrated around Station D, as well as trapping points for the reception track and putting the normal lie from the sidings so that any runaway was diverted from the mainline.

Would have liked to do and add in more but time did not permit.

But having said that I must still say that I enjoyed the layout and must say that in this attempt I was able to put in so much more than I have done so in the past.

It may however be still not good enough so we shall see.

Over the next few weeks may still submit for your comment an attempt on the 2004 layout, a comparison of ABCL, AOCL, AHBC distilled from RSPG 2E and GN 0642 (?) as well as reduced overlap/ROL distances extracted from one of the standards for posting on the Forum.

Cheers
Alex

[Peter]

(03-10-2010 05:24 PM)PJW Wrote:  During the time that the website was disabled whilst the exam was being undertaken at locations around the world, I received the following:

Quote:Dear Sir,

I have give the Mod-2 paper this year but i found that non-stopping headway required in the paper was give 600 sec. and after doing calculation the Dg-r distance comes nearly 20000 mtrs. which was too much as compared to Braking distance that comes nearly around 1000 mtrs. Also, with this calculations stopping headway(required is 3.5 min but theoritically it is comming 3 min 45 sec) can-not be achived. Is every thing right in the paper.
Not only me everyone in Hyderabad(India) faces the same problem. I do-not know whom to approach so i am wrieting to you as you were always helpfull to us.
Waiting for reply.

Amit Kumar Srivastava

The 10 minute headway part applies to a small section of the plan (see attached).

[PJW]

(03-10-2010 05:28 PM)PJW Wrote:  During the time that the website was disabled whilst the exam was being undertaken at locations around the world, I received the following:

Quote:Near Station D was a depot with two sidings, a train wash track, headshunt and reception track. I suppose the way to treat the depot was to treat it like a Freight depot.

Yes I think so- apart from there will be no need for run-round given the use of multiple unit stock I assume.

[quote]

As I had expected, the layout had a level crossing.

Well predicted. Indeed it hs been some years since a depot so that was also overdue a comeback. However there has not been a significant terminal layout I thinksince 1997 and therefore a couple of years ago I was predicting that, and have been proved wrong year after year so can't place too much faith in such predictions......

Quote:For non stopping which was for trains every 10 minutes, two aspect with distant signals was OK but the determinant was really the stopping.
No contingency for headway required - so even with stopping three aspect will do the job although as usual four aspect would be more suitable given the numerous junctions there. Headway required was 3.5 mins.

I'd like to see the question paper before comment too much on this. Certainly it seems as if the non stop headway was not at all onerous and this may have been what caused the consternation in Hyderabad; you seem to have recognised that the signalling also needs to deliver the stopping headway and therefore provided 3 aspects accordingly. Whether 4 aspects would actually be appropriate or whether it may have been better to have provided a few underbraked 3 aspects, with imposition of suitable approach release (modified aspect sequence) I cannot say at present.

Quote:I made... the mistake of using the distance for the headway of 120 km/h (1115 metres) instead of the permitted of 140 km/h (of 1515 metres) but discovered it in time before I started putting down the signals.

Classic mistake. At least you noticed and corrected, but of course the wasted time is itself extremely valuable.

Quote:Most of my effort was concentrated around Station D......
Would have liked to do and add in more but time did not permit.
But having said that I must still say that I enjoyed the layout and must say that in this attempt I was able to put in so much more than I have done so in the past.
It may however be still not good enough so we shall see.

Indeed, no value in worrying about it now; I suggest you give yourself a bit of a break. At least you enjoyed the experiece and felt you had made progress so even if you find that you need to re-sit next year it will be from a better base level.

Quote:Over the next few weeks may still submit for your comment an attempt on the 2004 layout, a comparison of ABCL, AOCL, AHBC distilled from RSPG 2E and GN 0642 (?) as well as reduced overlap/ROL distances extracted from one of the standards for posting on the Forum.

That's fine; I imagine it will be quite quiet for a bit. However I have some things that I must now get on with having been on the back burner for a while but send them in and I'll look at when I can.

[alexgoei]

Hello PJW,

Thanks again

Cheers

Alex

[AlastairHayden]

Hi all,

I can't help but notice the 2010 mainline layout looks extremely similar to the metro one...

[PJW]

(04-10-2010 09:32 AM)AlastairHayden Wrote:  Hi all,

I can't help but notice the 2010 mainline layout looks extremely similar to the metro one...

That certainly has happened in some past years. It makes sense to limit the workload for the volunteer designer- indeed some years I believe that ther have been no takers for the Metro layout at all. Obviously it depends on whether the same basic layout can be easily adapted to suit both environments.

[PJW]

(03-10-2010 05:48 PM)PJW Wrote:  

(03-10-2010 05:28 PM)Alex Wrote:  For non stopping which was for trains every 10 minutes, two aspect with distant signals was OK but the determinant was really the stopping.
No contingency for headway required - so even with stopping three aspect will do the job although as usual four aspect would be more suitable given the numerous junctions there. Headway required was 3.5 mins.

I'd like to see the question paper before comment too much on this.

Refering to the layout Peter has posted (not seen the actually question paper yet) it is clear to be that the majority of the traffic terminates at station G; on this stretch as Alex says it is the "Fast following stopping" consideration that dominates. I haven't done the sums but doesn't seem too onerous so can well believe that 3 aspects adequate to provide that headway.

Beyond the station where there are only two trains an hour then the quoted 10 minute headway would have plenty of contingency recovery already built into it so the section signals could be about 15 miles apart and still provide the headway- in reality it is probable that they would often be needed more frequently to protect junctions, level crossings etc; anything other than stop & distant signalling in this portion would be excessive.

Obviously there would need to be very little signalling on the freight single line branch- it could perhaps be token (or even train staff) worked with trains stopping to pick up / set down at station C.

So Amit, yes at first glance everything was right with the paper. The thing that you seem to have overlooked is that the only stated NON-STOP requirement was for the line beyond G to H. Obviously the same trains also use A to G, but because this was not the key factor here you should have signalled according to the FAST FOLLOWING STOPPING requirement.

[Peter]

2010 words.

[greensky52]

I remembered that the calculation result of 3 aspect for stopping train is bigger than Required Headway Time/110%, but less than the Required Headway Time. So I am confused about whether to use 3 aspect or 4 aspect. Finally I decided to use 4 near junction,3 aspect in other area, but time is tight, I do not have enough time to think how to arrange the transition of 4-3aspcet and 3-4 aspect, so I used 4 aspect almost in all main line....