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| Platform A/B query 17/04/2016 at 13:53 #81881 | |
Lyn-Greenwood
240 posts |
I've found what I believe to be an inconsistency in the Derby sim when an A or B platform is specified in a train's timetable. Here's the scenario: All platforms are empty. If a train enters at the A end with the A platform specified in the timetable, it only stops in the A platform if the train's next move is routed out of the A end. If the next move is out of the B end, then the train moves straight to the B end even though the A platform has been specified. However, if the stopping location is specified as 'Near End' in the timetable, then the train always stops at the correct end of the platform. I would have thought that specifying 'P3A' (say) for a train entering at the A end would equate to specifying 'P3 (Near End)' regardless of what the train's next move is. I've seen a Post in the 'Derby 2009 Timetable' section of the Forum that touches on this very problem, but not in much detail. Attached are 2 saves of a test timetable I've put together (adapted from the 2015 Weekday timetable) which demonstrates the inconsistency. Two trains enter from the B end: 5C98 is timetabled to use P3B and then go directly to Etches Park; 5C99 is timetabled to use P6B and then to Etches Park via Chad Curve. The latter works correctly and the train stops in P6B, but the former stops in P3A. Trains 5D78 and 5D79 demonstrate the same problem for trains entering from the A end. Save #1 shows 3 of the routes set up and Save #2 shows how everything ends up in the platforms. I don't know whether this behaviour is specific to the Derby sim or occurs in all sims. Does anyone know of this occurring in other sims? Post has attachments. Log in to view them. Log in to reply |
| Platform A/B query 17/04/2016 at 16:59 #81886 | |
Jan
906 posts |
It used to be the case that within the sim data stopping positions could only be defined per location. Since 4.5.5 it is possible to specify default stopping positions per platform as well, so if this does indeed work for for A-/B-ends, too, then Derby would need updating to take advantage of this new feature.
Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 17/04/2016 at 16:59 by Jan Log in to reply |
| Platform A/B query 17/04/2016 at 17:19 #81887 | |
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Lyn-Greenwood
240 posts |
" said:It used to be the case that within the sim data stopping positions could only be defined per location. Since 4.5.5 it is possible to specify default stopping positions per platform as well, so if this does indeed work for for A-/B-ends, too, then Derby would need updating to take advantage of this new feature.But this doesn't explain why things work OK when a train's next move is to move back out the way it came in, but not if it is to leave via the other end of the platform. Perhaps the sim developer can throw some light on this? Log in to reply |
| Platform A/B query 18/04/2016 at 11:46 #81894 | |
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Jan
906 posts |
I assume that the A/B ends are effectively just display labels and treated internally the same as the full platform - and unless overridden by the sim developer or a timetable, the default stopping position in Simsig is near end for reversing trains and far end for trains that continue straight through.
Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Log in to reply The following user said thank you: Lyn-Greenwood |
| Platform A/B query 18/04/2016 at 14:25 #81895 | |
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Lyn-Greenwood
240 posts |
" said:I assume that the A/B ends are effectively just display labels and treated internally the same as the full platform - and unless overridden by the sim developer or a timetable, the default stopping position in Simsig is near end for reversing trains and far end for trains that continue straight through.Thanks, Jan. That explains exactly what is happening. Looks like it's down to the timetable writer to choose 'Near End' if he wants a non-reversing train to stop at the entry end (normally to allow a reversing train to enter & leave at the other end). I wrongly assumed that because the timetable editor gives 3 options (A, B and Full platform), choosing B (say) would always ensure the train stopped there irrespective of which end it enters. I am now a much wiser man! Question is: should it be left to the timetable writer to override the default stopping position or should the sim be modified to cope better with the A & B platforms? Personally, I'm in favour of leaving it to the timetable writer. Thanks again for the explanation. Log in to reply |
| Platform A/B query 18/04/2016 at 14:46 #81897 | |
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JamesN
1607 posts |
It comes down to how locations are coded in the sim data - and it's not easy to do it automatically due to the way the sim works internally. A location is made up of lists of track circuits that make up each "platform". A train SimSig will attempt to use the full length available, unless it gets stopped by either another train or a red signal - take Cambridge platform 1/4 as an example. If you have a train booked in 1, but route it through 1 and into 4, it'll go to 4. Why? Because it allows the user to replatform trains as they wish, and at stations where platforms are split by mid-platform signals it works very well. For the odd cases like Derby, where 2 "separate" platforms are not divided by any signal, it doesn't work, and these cases are exactly why stopping point override was brought in. Log in to reply The following user said thank you: Jan |
| Platform A/B query 18/04/2016 at 15:19 #81898 | |
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Jan
906 posts |
" said:For the odd cases like Derby, where 2 "separate" platforms are not divided by any signal, it doesn't work, and these cases are exactly why stopping point override was brought in. What I'm wondering is whether the per-platform stopping positions (introduced through issue #14023) offer a solution there: So in the case of Derby, all three platform designations (e.g. 1, 1A, 1B) continue to be coded to the same track circuits (so replatforming between A and B end still works if half of the platform is already occupied), but with 1 using the default stopping positions, 1A set to far end in the up direction and near end in the down direction and 1B likewise to near end in the up direction and far end for down trains. Two million people attempt to use Birmingham's magnificent rail network every year, with just over a million of them managing to get further than Smethwick. Last edited: 18/04/2016 at 15:20 by Jan Log in to reply |
| Platform A/B query 18/04/2016 at 17:21 #81907 | |
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Lyn-Greenwood
240 posts |
" said:" said:The per-platform stopping positions facility seems to be exactly how I originally thought it all worked. If the timetable writer specifies P1B (say), then that is where the train should stop irrespective of which end of the platform it enters. Of course, if P1B is already occupied, then it's up to the operator to choose an alternate location. The train shouldn't end up in P1A just because that part of the platform is empty as P1A might be needed for a reversing train which arrives and departs before the original train is scheduled to depart.For the odd cases like Derby, where 2 "separate" platforms are not divided by any signal, it doesn't work, and these cases are exactly why stopping point override was brought in. There are several instances in the Derby 2015 Weekday timetable where a through train needs to stop at the entry end of a platform because another train is scheduled to use the other end. I believe there are also some instances in the 15 Oct 2009 Derby timetable. By the way, I've now got a better understanding of how it all works, so 'Thanks' to the two of you. Log in to reply |
| Platform A/B query 18/04/2016 at 18:22 #81910 | |
kaiwhara
587 posts |
" said:It comes down to how locations are coded in the sim data - and it's not easy to do it automatically due to the way the sim works internally.How did Southampton used to deal with it, because there were a lot of instances on timetables where a train needed to stop at the near end of the Platform (3A) for example from the Northam End, as a later arrival from the Redbridge End would berth from the other end while the first train was there? I don't recall at any stage having to define the stopping location... Sorry guys, I am in the business of making people wait! Log in to reply |
| Platform A/B query 18/04/2016 at 18:50 #81911 | |
GeoffM
6376 posts 
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This will repeat some of what's been said so no disrespect to those who already replied - just trying to explain it all in one post. Each location has a 3 options for trains stopping there: - Far end (default) - Near end - Near end only if reversing [otherwise far end] A while ago we added the ability to specify for each train individually where it should stop (near, far, or absolute positions - the latter should be handled with care if the train is replatformed into a short platform). More recently the above options can be specified per platform as well (including in each direction, but not 1/1A/1B where they are the same tracks) Now, as to whether a train timetabled to stop at 1, 1A, or 1B really depends on the location. At some stations drivers are instructed to proceed as far down the platform as the signals allow, and since Derby has no intermediate signals, that's all the way down the end (subject to options above). Other stations the driver might be instructed to stop in a particular half of a platform. From what I recall at Derby, short trains stop more towards the centre of the platform (straddling A and B ends), as it's close to the footbridge. And finally, it may not be at all obvious where platform 1A ends and platform 1B starts so it's a bit academic anyway! Maybe we'll add car stops ("4-car stop"  one day but experience in my previous job showed these don't always work too well, complicated by joins/divides etc.Edit: not the best picture for demonstrating "where does A end and B start" but here you can see platform signs with A and B on, but no obvious demarcation between. SimSig Boss Last edited: 18/04/2016 at 18:53 by GeoffM Log in to reply The following users said thank you: Lyn-Greenwood, Jan |
