Path signals for railroads / railway / train

[Ringgeest11]

Hey all,

I know there has been talk about path based signalling in the past and several topics both here and on Reddit. I also searched for a suggestion topic already concerning this topic, but I came up empty handed when it came to topics concerning introduction of Path based signalling.

As many of you are probably aware, OTTD uses path based signals (http://wiki.openttd.org/Signal#Path_signals) and they are extremely useful. They allow for extremely complex and fascinating results once you get the handle of them. Right now I am personally in hte bind I am constantly messing up the block signalling with the current signals and wishing for those path based signals. I think it would be a great idea to introduce the path based signalling.

For it being introduced into the game in a balanced fashion, you could have it as research that comes after the signal research requiring everything but Alien Artifacts.

[rampelstinskin]

I think it's better just replace block signals with path signals.
All existing railroads will work as is.

[ssilk]

Well, especially Kovarex meant, that he wants that. But if it will come? Not sure.

[Garm]

I would be just as happy if we could place signals in the middle of the curved track, and not just start / end...


But path signals would've been awesome too.

[roothorick]

joined -- ssilk

OpenTTD has a pretty clever signal system in the form of "path signals", which exploit the trains' own pathfinding algorithm to allow intersections that wouldn't normally be possible, including the dreaded "train circle". A pretty good explanation of how it works is on their wiki:

https://wiki.openttd.org/Signals#Path_signals

One caveat they don't mention: in their implementation, the path signals still establish a "block" which is arbitrated by the path signals leading into the block. Trains that initially fail to path due to another train will (usually) wait until that other train has left the block entirely before proceeding, even if the path becomes clear much earlier than that. A smarter implementation would "cache" the conflicted rail tile and attempt to re-path and proceed once that specific tile is cleared, regardless of the state of the rest of the block. (Hell, even the concept of a block wouldn't be necessary at that point.)

It's a little unrealistic, as it needs at the very least for every train to have relatively advanced navigation systems that plot out its route well in advance and communicate directly with the signals. But hey, Factorio has already stepped across that line.

[ssilk]

Roothorik, do you have a twin?

And when I'm on this:

https://forums.factorio.com/forum/vie ... ?f=6&t=970

https://forums.factorio.com/forum/vie ... f=6&t=2091

https://forums.factorio.com/forum/vie ... f=6&t=1700