Question on signals

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sudanec
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Question on signals

Post by sudanec » 13 Apr 2018 21:48

Hi guys,
an amateur question here. I am building a double-circular rail network, one stream of trains moving clockwise, the other counter-clockwise, and I want them to share the stations (schema attached, original idea is with ~6 stations). But it does not work.. :) could you, please, explain to me why? It would work if I'd put path signals also next to the stations, but I believed this should work also without the signals to save some space - why not?
Thank you,
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kamnet
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Re: Question on signals

Post by kamnet » 13 Apr 2018 22:15

If your intent is to have both platforms be filled with trains from either direction, you might try an exit signal sitting on each platform end. But I don't think this would be very efficient and would quickly lead to gridlock.

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Re: Question on signals

Post by Eddi » 13 Apr 2018 22:33

the "works without signals" myth only applies when the station is at the end of the line. you must use two-way path signals there (exit signals also will not work properly)
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Re: Question on signals

Post by piratescooby » 13 Apr 2018 22:43

My typical circular setup , clock/anti , I used one way path signals .Easy enough to expand ,just add multiples of 2 platforms for stations .
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Re: Question on signals

Post by Alberth » 14 Apr 2018 04:34

To elaborate on the post by Eddi, you are missing the two-way path signals directly around the platforms, see https://wiki.openttd.org/Signals#Basic_two-way_station Note they are facing toward the platforms!

At the connecting tracks between stations, the normal strategy is to leave enough room to fit an entire train between a junction and the first signal after the junction. In that way, it will never block the junction if it has to wait for the signal. In your picture, the one-way path signals halfway on the inner track would not be there, since there is no 4 tile space before it (assuming 4t as train length, matching the length of the platforms).
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Re: Question on signals

Post by sudanec » 14 Apr 2018 07:04

Thanks to all of you. Yes, I am aware with the path signals next to the station it will work, that is the normal setup. However, I was hoping there is a way to save one tile and use some "implicit" working of the station as a safe waiting point.
Anyway, thanks for your reactions.

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Re: Question on signals

Post by Alberth » 14 Apr 2018 14:34

sudanec wrote:Thanks to all of you. Yes, I am aware with the path signals next to the station it will work, that is the normal setup. However, I was hoping there is a way to save one tile and use some "implicit" working of the station as a safe waiting point.
Anyway, thanks for your reactions.
Ah, right.

A train entering a block with a path signals claims a path to the next signal or to a dead end. A terminus station will work without additional signals as it counts as a dead end.

If that is not feasible, the claimed path behind the platform should not cross tiles needed by trains from the other direction. The obvious solution is to add a signal directly behind the platform, or to separate platforms and tracks for a single direction only, eliminating the need for junctions.
It may also be possible to design a split to both platforms such that traffic from the other side does not use the same track, eg by a bridge rather than a junction. Not likely to be more compact though, so mostly a theoretical solution, I think.

Other option can be to rotate the station 90 degrees, and enter the platforms from one side, and exit at the other side. In that case you only need signals at the exit side.


None of the above beats adding a tile with signals at both sides, it seems :)
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Re: Question on signals

Post by Chrill » 14 Apr 2018 17:51

As such.
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Re: Question on signals

Post by Pyoro » 14 Apr 2018 18:16

Technically you could perhaps go for this variation that avoids the signals at the stations by using depots instead (no space saved of course):
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I'm not rating the idea very highly though :mrgreen: Might not even work, actually. ^^

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Re: Question on signals

Post by Alberth » 15 Apr 2018 04:51

I like the idea, but indeed, it fails in the sense that a train will not always leave, since the next train that was waiting in the depot before the platform will claim the tile in front of the depot, thus blocking the path of the leaving train.
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Re: Question on signals

Post by Pyoro » 15 Apr 2018 11:23

I think it actually works, since trains reserve through the station to the depot. So exiting trains always have priority.
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But it might be that there are cases were it breaks - as you can see, it's a signal-less network, except for the ones to ensure trains go in certain directions. I wondered whether having multiple depots between stations would confuse them (without giving explicit orders) but that seems to work fine, too.

If I used, say, waypoints instead of those one-way signals I'd claim it'd be possible to build a network without signals. ^^;

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Re: Question on signals

Post by vrn » 15 Apr 2018 12:02

Pyoro wrote:If I used, say, waypoints instead of those one-way signals I'd claim it'd be possible to build a network without signals. ^^;
I think you'd need at least one PBS signal somewhere, otherwise the built-in depot signals would act like block signals, so only a single train could be out at a time.

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Re: Question on signals

Post by sudanec » 15 Apr 2018 18:08

Thank you all, now I finally understand how the station-in-built signals work. In the end, I simply added the signals.
Btw, it would be stupendous if we could export the train network we build into a graph, let's say a .graphml or an XML, I'd love to play with theoretical optimizations with some graph theory on that :) Now after the weekend my network got somewhat crazy, works well but could surely work better.

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Re: Question on signals

Post by Alberth » 15 Apr 2018 18:41

I remember that someone made a new output stream that generated a graphviz file from the program. Don't know if it was ever published, I had a quick scan through the issues, but I didn't find it. It might be at the development forum, but I didn't try that.
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Re: Question on signals

Post by agentw4b » 15 Apr 2018 19:05

Alberth wrote:I remember that someone made a new output stream that generated a graphviz file from the program. Don't know if it was ever published, I had a quick scan through the issues, but I didn't find it. It might be at the development forum, but I didn't try that.


?!? viewtopic.php?f=32&t=72741
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Re: Question on signals

Post by Alberth » 16 Apr 2018 04:30

agentw4b wrote:
Alberth wrote:I remember that someone made a new output stream that generated a graphviz file from the program. Don't know if it was ever published, I had a quick scan through the issues, but I didn't find it. It might be at the development forum, but I didn't try that.
?!? viewtopic.php?f=32&t=72741
Yep, looks like it, thanks.
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Re: Question on signals

Post by agentw4b » 16 Apr 2018 16:28

Alberth wrote:
agentw4b wrote:
Alberth wrote:I remember that someone made a new output stream that generated a graphviz file from the program. Don't know if it was ever published, I had a quick scan through the issues, but I didn't find it. It might be at the development forum, but I didn't try that.
?!? viewtopic.php?f=32&t=72741
Yep, looks like it, thanks.
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If I used 2 server games on the same server as a client-server for the admin port, do you think one game can send data and the other game receive data if they have the same IP and the same adminport?
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Re: Question on signals

Post by Eddi » 19 Apr 2018 21:46

you cannot ever run two programs on the same IP and Port
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