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Impasse

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Impasse 21/07/2020 at 04:24 #129825
VInce
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Hi all,

See attached screen grab and save - this has been the situation now for over 35 minutes with 5 trains or LDs waiting acceptance into Nene CS.

Nene usually only refuses to accept trains when there is a train about to leave the sidings. The only train due from Nene CS (aside from unscheduled shunts) is 5D16. This will never leave the sidings because the engine to work it is one of those waiting to enter.

A similar situation has arisen before and I had to provide a work around to enable the Peterborough 1977 timetable to work - thread is here...

https://www.simsig.co.uk/Forum/ThreadView/50516?postId=123749

I can't provide a work-around in this case.

Are we any further forward with this please?

Vince

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I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
Last edited: 21/07/2020 at 04:57 by VInce
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Impasse 21/07/2020 at 10:52 #129829
JamesN
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Just asking on a hunch Vince, how many trains have gone in to Nene CS in the course of your run so far? And if possible to tell what's their total combined length?

There's a seldom-used (and if it is on Peterborough) undocumented feature whereby an exit location can have a maximum capacity - if that capacity has been reached then the location won't accept any more trains until some have come back out.

If that feature is in use here (I don't know that is is for certain) then it may explain why they're refusing trains, and lead down a road of perhaps the values used in implementing that aren't quite right and need tweaking.

Last edited: 21/07/2020 at 10:53 by JamesN
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Impasse 21/07/2020 at 12:04 #129832
jc92
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JamesN in post 129829 said:
Just asking on a hunch Vince, how many trains have gone in to Nene CS in the course of your run so far? And if possible to tell what's their total combined length?

There's a seldom-used (and if it is on Peterborough) undocumented feature whereby an exit location can have a maximum capacity - if that capacity has been reached then the location won't accept any more trains until some have come back out.

If that feature is in use here (I don't know that is is for certain) then it may explain why they're refusing trains, and lead down a road of perhaps the values used in implementing that aren't quite right and need tweaking.
Or the values are correct but the timetable overuses the sidings. When I wrote the 80/81 Euston timetable I kept a tracker going on a spreadsheet to ensure this didn't happen.

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Impasse 21/07/2020 at 12:55 #129834
Steamer
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If capacity limits are enabled, there should have been a warning when the sidings started reaching capacity. There's no mention of a capacity limit in the manual, but it would need Clive to confirm.

Vince- unfortunately, I think the only way you'll be able to resolve the issue in the short term is to remove 0D16, which should allow 5D16 to enter after any rule delay has elapsed.

"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
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Impasse 21/07/2020 at 15:21 #129840
Hap
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Only way I managed to get things moving was to debug a train to enter from the C.S. After that everything was accepted fine.
HAP
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Impasse 21/07/2020 at 16:43 #129841
clive
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There is no rolling stock capacity checking on Peterborough. Adding it is Mantis 17756.

I've looked at your saved game. The "train about to enter at Nene" flag is set; this flag gets set when a train is ready to enter and cleared when it actually enters. I can't see any train ready to enter, so I don't see why the flag is set.

That suggests that you can clear the logjam by entering a train from the sidings and removing it as soon as it enters; I'd like to know if that works.

Did you remove any train due to enter at Nene? I wonder if there's a race condition somewhere.

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Impasse 21/07/2020 at 16:50 #129842
clive
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Hap in post 129840 said:
Only way I managed to get things moving was to debug a train to enter from the C.S. After that everything was accepted fine.
Right; that's because the flag got cleared. That's reassuring to know.

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Impasse 21/07/2020 at 16:51 #129843
clive
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Vince: is this reproducable in a new game? Or at least from an earlier save (preferably from before the last time a train left Nene sidings. Do you have a full set of snapshots leading up to the first instance of the problem. If so, can you email me directly?
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Impasse 21/07/2020 at 16:56 #129845
jc92
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clive in post 129841 said:

I've looked at your saved game. The "train about to enter at Nene" flag is set; this flag gets set when a train is ready to enter and cleared when it actually enters. I can't see any train ready to enter, so I don't see why the flag is set.
Blue sky thinking, could this have been caused either by late running where a train is due to enter but is delayed, or possibly a TT rule where something is due out but is being held by said rule? Similar to when an on time train rings at a siding and is told to wait 15 mins, a message normally follows advising it will be 15 minutes late entering.

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Impasse 21/07/2020 at 17:53 #129848
VInce
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Clive,

Thank you. I've got snaps every 10 minutes from 0010. I'll zip them and send them to you.

I will run a save from 0300 again and see what happens.

I drop you a PM on the forum mail to get your e-mail address.

I didn't remove any trains. In recollection, the only thing I did was (very much earlier) refuse a train offered by Nene for 2 minutes due to no platform availability. If kept being re-offered very quickly, certainly less than 2 minutes. I then refused it for 5 minutes which worked OK. It was re-offered accepted and ran OK.

I'm trying to remember which train that was. If I do I'll let you know.

Edit - I've remembered. It was 0B06-50/ZCH782 which was offered around 0235-ish out while both P4 and P5 were occupied. P4 had the vans to form 1B08 and 1B09 detached off 1L00 and P5 had 0B08 and 0B09 which were waiting for 1L00 to leave before they could shunt to P5 and attach.

The situation really started when I offered LD 0B06-42SX/ZBD563 which was crossed over from the USL to P4 around 0355 sim time. It was refused by Nene and I then shunted it to the DSL (south) so as there was a path for anything that might leave Nene, but nothing did. 0B06-42 is the loco currently standing on the DSL.


Vince

I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
Last edited: 21/07/2020 at 18:24 by VInce
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Impasse 21/07/2020 at 19:08 #129853
VInce
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Hi all,

I tried running again from the 0250 save and it didn't reproduce. 0B06-42 accepted straight in.

Whether we should expect it to I'm not sure. Train are delayed differently and are in a different place on a second run through than they were in the original.

Vince

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Impasse 21/07/2020 at 21:52 #129859
VInce
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Hi all,

I may be going off at a tangent here, but I wonder if the NNCS shut moves have anything to do with this.

Early on in the "shunt moves" incarnations there was an issue with an extra shunt (after the finish time) asking to run but this was soon rectified.

Shunt moves (NNCS) from Nene finishes at 0400 - co-incidence?

Vince

I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
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Impasse 21/07/2020 at 22:16 #129860
clive
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jc92 in post 129845 said:
clive in post 129841 said:

I've looked at your saved game. The "train about to enter at Nene" flag is set; this flag gets set when a train is ready to enter and cleared when it actually enters. I can't see any train ready to enter, so I don't see why the flag is set.
Blue sky thinking, could this have been caused either by late running where a train is due to enter but is delayed, or possibly a TT rule where something is due out but is being held by said rule? Similar to when an on time train rings at a siding and is told to wait 15 mins, a message normally follows advising it will be 15 minutes late entering.
The flag shouldn't get set until later than that. In any case, I should have been able to see a train waiting to enter in the saved game. Nice thought, though.

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Impasse 21/07/2020 at 22:20 #129861
clive
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VInce in post 129859 said:

I may be going off at a tangent here, but I wonder if the NNCS shut moves have anything to do with this.

Early on in the "shunt moves" incarnations there was an issue with an extra shunt (after the finish time) asking to run but this was soon rectified.

Shunt moves (NNCS) from Nene finishes at 0400 - co-incidence?
I think it may be related, though I can't see how.

In the 04:00 save the flag is clear; in the 04:10 save it is set. There are well over 1000 differences between the saves but one that sticks out is that NNCS/ZHD826 has a delay of 04:02:22 in the 04:00 save while that's gone in the 04:10 save and instead it's moved to a later point in the entry logic.

What do you mean by "issue with an extra shunt [that] was soon rectified"?

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Impasse 21/07/2020 at 22:23 #129862
clive
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By the way, thanks for all the saves.
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Impasse 21/07/2020 at 23:00 #129863
VInce
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Clive,

I recollect when shunt moves was first created (some while ago now) there was often an additional shunt that would show up after the set finish time.

This was reported as problem (bug) and rectified soon after. It just crossed my mind that it may be a hangover from that.

Vince

I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
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Impasse 21/07/2020 at 23:46 #129864
VInce
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Clive,

Another thought - when these shunt moves take place they only just come out of Nene and almost immediately set back in. They only occupy T9969 before returning inside of GPL P65 by using a stopping point of NX@250.

These shunt moves thus leave the route from GPL P65 to either P4 or P5 set (with P65 now at red) which then has to be be cancelled and timed off.

I don't know what process tells the system that the train has entered (thus resetting the flag) from the sidings. Is it the occupation and then clearance of T9969 and then the occupation and clearance of the next T/C towards either P4 (T7643) or P5 (T7601) in the normal sequence?

If so, then I'll just eliminate the shunt moves from the timetable. It was only put in for a bit of realism.

Vince

I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
Last edited: 22/07/2020 at 05:56 by VInce
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Impasse 22/07/2020 at 08:07 #129869
clive
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VInce in post 129863 said:

I recollect when shunt moves was first created (some while ago now) there was often an additional shunt that would show up after the set finish time.

This was reported as problem (bug) and rectified soon after. It just crossed my mind that it may be a hangover from that.
I don't recollect that (it wasn't my code), but that wouldn't explain the problem you're seeing. If I'm understanding you correctly, this was a genuine shunt move, just at the wrong time. That wouldn't produce these symptoms.

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Impasse 22/07/2020 at 08:14 #129870
clive
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VInce in post 129864 said:

Another thought - when these shunt moves take place they only just come out of Nene and almost immediately set back in. They only occupy T9969 before returning inside of GPL P65 by using a stopping point of NX@250.

These shunt moves thus leave the route from GPL P65 to either P4 or P5 set (with P65 now at red) which then has to be be cancelled and timed off.

I don't know what process tells the system that the train has entered (thus resetting the flag) from the sidings. Is it the occupation and then clearance of T9969 and then the occupation and clearance of the next T/C towards either P4 (T7643) or P5 (T7601) in the normal sequence?
Sorry. Good thinking, from your point of view, but wrong.

The flag is set whenever a timetable entry is tagged as about to enter (there's a number of internal processes that happen a minute or two before the train tries to enter). It is cleared when a train entering at Nene actually gets created in the sim and so appears in the F2 list. I can see some ways to improve the logic and catch some corner cases, but since I don't know what triggered your problem I don't know if they would prevent it. I can also see a rewrite that would ensure this could never happen again, but it requires core code changes and a loader update.

Please don't change your timetables just because of this bug. There is a work-around for now (create a train, let it appear, remove it) and it'll eventually get sorted.

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Impasse 22/07/2020 at 09:51 #129871
VInce
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Clive,

Thanks for that - I'm grateful for the time you've taken with this.

I'll leave well alone for the time being then.

Regards,

Vince

I walk around inside the questions of my day, I navigate the inner reaches of my disarray, I pass the altars where fools and thieves hold sway, I wait for night to come and lift this dread away : Jackson Browne - The Night Inside Me
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