Why does this train signal setup result in stuck train?

[matt.gulick]

I know why, I just don't know how to do it right.

I have watched so, so many videos on train signals, and it took me a long, long time to understand how to use path signals. My trains don't crash anymore but sometimes they get stuck, so I watched and re-watched more train videos, but I can't figure it out. I think I must have a leaning disability.

See Image
https://i.imgur.com/odBEnrE.png

[Bainen]

I had a similar issue last night and it was infuriating. I had been carving up the tracks to insert a new station with the various twists and turns of the track. At some random point, my trains suddenly had no path to their station, despite there being obvious paths and no signal alarms. I ended up having to delete and re-place some track sections and (maybe) some signals to make it work. What specifically fixed it? No idea, it just... worked at some point without any logical resolution that I could find.

If you haven't already try taking a train and manually drive it on each path, I once found a track that should be switchable not being switchable that way - I'd suggest just an engine, no rail cars, so you can easily delete the engine to move it vs finding a spot to turn around.

The screenshot cuts off the left and upper signals but based on what I see you have a path signal at every 'entrance' and a block signal at every 'exit', going each direction, which is indeed correct. I'm not seeing any alarms on the path signals in the pic, so perhaps the issue isn't the signals themselves and maybe a track misbehaving?

If it's any consolation, I played over 1000 hours of the game before path signals finally 'clicked' despite watching several videos and just not understanding the logic.

The game really needs a rail debugger so we can see the logic causing the issue.

[Schlappspaten]

"They get stuck" should be explained in more detail, Like "endless waiting" or "train vs. train" at signals. The tracks don't tell the story of timetables and directions.

[Eiko]

It's hard to tell without seeing the context, but you probably don't want a single track with a block signal in one direction and a path signal in the other. And you have 5 of them here. That *might* be OK if there's no way you can ever have trains on opposite sides of the path block wanting to go into each-others' blocks. But if that ever happens they'll deadlock.

If at all possible, make the double track sections leading into this block right-hand-running.

The single track on top is a bigger problem. Assuming there's a merge somewhere above the screen, you can move the signals back to that so that one signal is on each track.

[Bobucles]

What a messy train setup. Trains can drive both ways on both rails, that's messy. The branching path can only be reached by the top rail, which is also messy. Trains will not drive through a junction, stop, and backup to make a turn. They must have a single forward route.

The junction is a single green block. That means every direction has to take turns driving through. A pair of trains can not pass through going the same direction, nor can they go in opposite directions. That is what a single color block means.

[RadioIesbian Fluid]

Try something like this instead. Signals are directional, they can get confused when you have a track thats signaled in both directions. Have the traint tracks be one way and it works infinitely better.

https://steamcommunity.com/sharedfiles/filedetails/?id=3361073118

[Hashy1000]

Originally posted by Bobucles:

What a messy train setup. Trains can drive both ways on both rails, that's messy. The branching path can only be reached by the top rail, which is also messy. Trains will not drive through a junction, stop, and backup to make a turn. They must have a single forward route.

The junction is a single green block. That means every direction has to take turns driving through. A pair of trains can not pass through going the same direction, nor can they go in opposite directions. That is what a single colour block means.

Agreed its messy but 2 trains can pass or go opposite directions. another quirk of this game how it doesn't use blocks properly when using path signals, almost like the game puts invisible path signals in a path block, I've seen it its easily reproducible

[Bobucles]

another quirk of this game how it doesn't use blocks properly when using path signals

But that's... not good. How will a chain signal know which combination of routes is valid for 2 trains? There's a reason blocks have a 1 train per block limit. I dunno, I seriously doubt that's what happens, but to be fair I've seen trains flicker signals as they're driving through blocks. That's also extremely bad.

[Nellvan]

Originally posted by Hashy1000:

Originally posted by Bobucles:

What a messy train setup. Trains can drive both ways on both rails, that's messy. The branching path can only be reached by the top rail, which is also messy. Trains will not drive through a junction, stop, and backup to make a turn. They must have a single forward route.

The junction is a single green block. That means every direction has to take turns driving through. A pair of trains can not pass through going the same direction, nor can they go in opposite directions. That is what a single colour block means.

Agreed its messy but 2 trains can pass or go opposite directions. another quirk of this game how it doesn't use blocks properly when using path signals,

Maybe I'm missing something here, but that's exactly the purpose of path signals? To allow more than one train into a block IF their paths don't collide.

They way you describe it, they'd act just the same as block signals, why even have them then?

As for the OP, I agree that it' just too messy. Without seeing the context I'm not sure what youre trying to do here, though. If left and right are 2-lane lines that keep going on like that, I'd keep each lane only going into one direction.

If that's 4 bi-directional lines, you'll need some bypass / waiting area at least up on top of the spiral, maybe down to the left and right too.

*edit*
As Eiko said above, it might be enough to remove the signals on the spiral (upper left in the picture), if there's a properly signalled split/merger up there.

[Bobucles]

To allow more than one train into a block IF their paths don't collide.

It's bad, because the only way you can actually do that is to fully 3d map out the entire junction. Trains are 3d, their movement is 3d, and they crash in 3d. Trains will crash and continue to crash if path signals allow trains to share blocks, but can't work out the 3d problems. That means chipping up a block into piles of smaller blocks, measuring out shoulder room and all that, outside the player's control, defeating the purpose of using a block system in the first place. It creates a problem, then doesn't provide the solution for it.

One block, one train. It's a very easy system to work with. This is a case where copying the homework from other games with more robust train systems would have been the right play.

They way you describe it, they'd act just the same as block signals, why even have them then?

The point of a GOOD path signal is to deal with block dependencies. A train can't just drive halfway through a turn and stop. It will get in the way of everyone else. A proper pathing signal would tell the train "no you can't stop here, wait until the whole path is clear". That's a good system.

But to be fair I don't understand how path signals work or what they're supposed to do. Whatever set of rules they're following, doesn't make any sense.

[Hashy1000]

From what I've seen they will allow as many trains in the block as you like as long as the path doesnt cross within the block, I will try and create a screenshot to show an example, to stop deadlock you would need the block after the path signal block to be longer than any train using that section of track

[Hashy1000]

Here it is https://steamcommunity.com/sharedfiles/filedetails/?id=3361176291
2 trains occupying the same block, both set on autodrive, could have tried to set up to show both engines but I was having to turn off and back on selfdrive to line trains up to demonstrate this, something I noticed while riding a train a couple of days ago

[Hashy1000]

In every other train game and real life only 1 train can ever occupy a block at any given time. this is the safety feature that all blocks are built around. other games represent this with green red and blue light upon the path signal, to show clear, blocked and reserved respectively. I played alot of sweet transit, train game made by the developer who worked on trains within factorio, and although I dont like factorio at least it does trains properly

[Hashy1000]

Originally posted by Bobucles:

another quirk of this game how it doesn't use blocks properly when using path signals

But that's... not good. How will a chain signal know which combination of routes is valid for 2 trains? There's a reason blocks have a 1 train per block limit. I dunno, I seriously doubt that's what happens, but to be fair I've seen trains flicker signals as they're driving through blocks. That's also extremely bad.

Trains do not reroute they determine their path before they leave the station, hence why you cannot use holding yards or in factorio terms a stacker

[Nellvan]

Originally posted by Hashy1000:

to stop deadlock you would need the block after the path signal block to be longer than any train using that section of track

This.


A path signal checks two things: 1) Is the path this trains wants to take free to use? 2) Is the next block signal, the one that marks the end of this trains' path, green?

Only if both are true, the train will pass. You put an exit block behind the intersection, that is just big enough to fit the longest train your using.

Now the path signal will stop the train from entering if it cannot cleanly exit on the other side.

And from what I've seen so far, while such a train waits for it's exit to clear it will not reserve the path, so other trains that want to eg. go across from another side can do it.

[Dr.Acula]

Why do you have multi directional signals on the various tracks? I think there is your problem.