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4M78 Overlap not dropping out

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4M78 Overlap not dropping out 24/09/2022 at 15:33 #148113
bugsy
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I'm playing the Staffordshire 300220 + Extras timetable and have 4M78 sitting in platform 5 awaiting a crew change. Tt's been there for quite some time, but the overlap hasn't dropped out. Should it have done?

I was hoping to divert a couple of trains via the Goods loop to keep them moving but have been unable to do so.
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04:10 save attached


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4M78 Overlap not dropping out 24/09/2022 at 15:38 #148114
HST125Scorton
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I think it has to do with 4M78 rear still within the overlap of Signal LS5583. Otherwise normally cancelling that signal which you have done normally drops the overlap.
Aaron (AJRO) | Timetable Writer
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4M78 Overlap not dropping out 24/09/2022 at 15:47 #148115
bugsy
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HST125Scorton in post 148114 said:
I think it has to do with 4M78 rear still within the overlap of Signal LS5583. Otherwise normally cancelling that signal which you have done normally drops the overlap.
I trust that you mean LS5583.
Yes, because I saw that the signal stem was still illuminated and thought that by cancelling the route from there into P5 it would drop the overlap, but it hasn't. So I had to wait for the crew change to finish.

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4M78 Overlap not dropping out 24/09/2022 at 15:55 #148116
Hap
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You are best using the yellow triangle for the reduced over lap into platform 5. That would stop you having this issue.
How to report an issue: www.SimSig.co.uk/Wiki/Show?page=usertrack:reportanissue
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4M78 Overlap not dropping out 24/09/2022 at 16:25 #148122
bugsy
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Hap in post 148116 said:
You are best using the yellow triangle for the reduced over lap into platform 5. That would stop you having this issue.
Ah, yes. I didn't think of that. :/
Good solution, but unfortunately, it's too late now.

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4M78 Overlap not dropping out 23/10/2022 at 00:34 #148435
Guts
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In my humble opinion, the overlap should still die out is the signal in rear is cancelled. Sounds like a bug to me.

For example (I hope it's relevant, someone will argue not), last week we had a TCF in the route from Platform 10 at Euston (route-locked after oversetting a route from Platform 9) to WM309.
We examined with a train and when the train came to a stand at WM309 to report back; cancelled the route in rear from Platform 10 and the overlap ahead of WM309 died out, which allowed us to run around the route-lock till the S&T and the MOM found Schwarf (metal fillings) on the block joint and cleared the TCF.
There had been a concern that the overlap wouldn't die out because of the TCF but it did.

Just my humble real-life railway experience.

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4M78 Overlap not dropping out 25/10/2022 at 17:33 #148474
Izzy
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Guts, your humble opinion is correct.

In the real world, the overlap sh/would time out after a specific timer provided for this and only this function (expensive). This was normally only provided at station platforms or where long trains were expected to stop for whatever reason. You wouldn't normally expect to have to set the warner route from rear in this situation. Normally for a route to cancel completely, requires the route in the track section in rear to clear to ensure the route cancels in the direction that the train has passed through (this is especially important on a reversible line). However in certain circumstances (a station platform being one of them), a timer can be provided to bypass a very small part of the route releasing conditions. (I have only talked about relevant conditions here - there are a few others).

I suspect the Simsig core code simulates the former but not the latter as i have noticed this in a few places in a few sims - it has never really bothered me that much, because i'd rather have the odd error in Simsig, than not have it at all (Yes, that is praise for the devs, in case i was too subtle).

Well, that's my small contribution done with, just a mini-essay this time :)

Happy signalling :)

P.S. While i think about it - the other work around from setting the warner route would be to peg all the points and talk past from the signal in rear - then none of the overlap would be used at all. This would be frowned upon in the real world, though.

Last edited: 25/10/2022 at 17:39 by Izzy
Reason: None given

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4M78 Overlap not dropping out 25/10/2022 at 17:48 #148475
GeoffM
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Izzy in post 148474 said:
I suspect the Simsig core code simulates the former but not the latter as i have noticed this in a few places in a few sims - it has never really bothered me that much, because i'd rather have the odd error in Simsig, than not have it at all (Yes, that is praise for the devs, in case i was too subtle).
There are several sims where platform subroutes release after a timeout, eg to allow for an opposing call-on into the same platform from the opposite end. If you're aware of any sims where it's missing then please let me know.

SimSig Boss
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4M78 Overlap not dropping out 25/10/2022 at 18:02 #148476
Izzy
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No current sims, that i can think of Geoff - sorry, i should have made that clearer. I also apologise for any extra work i may have caused you by explaining things.
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