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Author Topic: Help: Train inexplicably stuck  (Read 254 times)

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Offline passengerpigeon

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Help: Train inexplicably stuck
« on: June 09, 2021, 06:11:08 PM »
On the savefile I have attached here, the train between Hollyingridge and Intock refuses to pass a token block signal despite currently being the only train on the line. WHY!?

Edit: Never mind, it seems to have been fixed when I demolished the signalbox and rebuilt both the box and signals in the exact same place.

https://drive.google.com/file/d/1GjLNr8_Q6RovJkuI7pZt4LQpWfeVpF-P/view?usp=sharing
« Last Edit: June 10, 2021, 03:03:15 AM by passengerpigeon »

Offline Matthew

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Re: Help: Train inexplicably stuck
« Reply #1 on: June 10, 2021, 03:21:55 AM »
I opened the file to have a look at almost exactly the time as you edited your post.  :-[

I think the game was designed expecting players to operate this layout using absolute block Stop signals, not token block.

I know that in real life a token block system would be able to handle your layout, but due to the immense complexity of the signalling code, I think it's only tested with what James considers the optimum signalling system for a given layout.

Offline passengerpigeon

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Re: Help: Train inexplicably stuck
« Reply #2 on: June 10, 2021, 11:16:18 PM »
I think the game was designed expecting players to operate this layout using absolute block Stop signals, not token block.

Ah, this sort of single-track layout can be worked with absolute block signals? I was not aware of that; what is the usual (intended in the game) usage of token block signals, then?

Offline Matthew

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Re: Help: Train inexplicably stuck
« Reply #3 on: Yesterday at 11:30:39 AM »
Ah, this sort of single-track layout can be worked with absolute block signals? I was not aware of that; what is the usual (intended in the game) usage of token block signals, then?

James/Extended expects token block to be used when you have stations on a single-track line without a passing loop. For example, I added this station to your savegame:



You can see that the station has no passing loop and no signals. Access to it is controlled by the token block signals at the passing loops either side. Interestingly, when I built this station, the (previously stuck) train immediately departed. This supports my theory that it was stuck because of an unanticipated layout.

Offline passengerpigeon

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Re: Help: Train inexplicably stuck
« Reply #4 on: Yesterday at 05:28:56 PM »
James/Extended expects token block to be used when you have stations on a single-track line without a passing loop.

I have since added a narrow-gauge railway line to the same map, which does have several single-track stations in between token block passing loops, and now this too is broken - trains enter the single-track section two at the same time and get deadlocked. When using the block reservation view, it seems that in between certain passing loops (seemingly no rhyme or reason as to which ones), the trains only reserve track as they go and not the whole block. According to the menus, however, the trains that do this are still apparently taking the tokens and not driving by sight.

Savefile: https://drive.google.com/file/d/1BA6fn_-4TO6_l2NYUd9TlJGeFPKA_JYN/view?usp=sharing
« Last Edit: Yesterday at 06:29:11 PM by passengerpigeon »

Offline Matthew

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Re: Help: Train inexplicably stuck
« Reply #5 on: Today at 05:15:05 AM »
I have since added a narrow-gauge railway line to the same map, which does have several single-track stations in between token block passing loops, and now this too is broken - trains enter the single-track section two at the same time and get deadlocked. When using the block reservation view, it seems that in between certain passing loops (seemingly no rhyme or reason as to which ones), the trains only reserve track as they go and not the whole block. According to the menus, however, the trains that do this are still apparently taking the tokens and not driving by sight.

Savefile: https://drive.google.com/file/d/1BA6fn_-4TO6_l2NYUd9TlJGeFPKA_JYN/view?usp=sharing

It is still the same 'problem': the layouts on this line are not the layouts that James considers optimal and therefore the signalling system cannot cope. I was able to make token block signals work correctly in the block without passing loops like this:



① ② Replace the token block signals for the adjoining blocks (which do not have stations in them) with absolute block signals.
③ The second, eastbound train is then prevented from entering the block containing stations at the token block signal, because the westbound train has resolved the whole block.

I totally sympathize with your situation because a real token block system would be able to handle your layout without difficulty. But the Extended signalling system does not actually use tokens; it  makes a hideously complex series of choices depending on what is in front of the train. No one is clearer than James that, with the benefit of hindsight, this was not a great design. But re-writing the signalling code would be an enormous undertaking that would probably take several years without introducing any new features. That the signalling code works as well as it does is greatly to James' credit.

Online Freahk

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Re: Help: Train inexplicably stuck
« Reply #6 on: Today at 08:44:52 AM »
I'd like to add that this layout worked perfectly fine some time ago, thus the suggestion might be a good workarround but it's still a bug.