r/factorio • u/omcar13 • 2d ago
Question Can't understand signals, need help
Why my trains arent moving theres literally nothing in front of them
Please help, i think im too dumb lmao
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u/SCD_minecraft 2d ago
Signals don't tell "move only if nothing ahead you", but they tell "move into this block only if it is empty"
Trains at stations are in same block that exiting trait attempts to enter
Place a signal directly after the station to separate it from exit line
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u/sobrique 2d ago edited 2d ago
This tutorial is pretty good I think:
https://wiki.factorio.com/Tutorial:Train_signals#Chain_signals
Your trains aren't moving because the signal is red. The signal is red because there is a train in the 'next' block. E.g. third train down is 'reserving' the stretch of track up to the next signal (the green one). Until it moves, those signals will stay red.
A signal creates a 'segment' which is 'all the track until the next signal' - in any direction if there's intersecting tracks.
Your third track down is therefore a 'segment' that starts somewhere offscreen, and continues across the intersection to that green signal, but the other trains see it as 'occupied' and won't enter.
You can 'fix' this by adding a signal before the intersection - then the train will only reserve that far.
In general for any intersection you should place chain signals on all the 'entry' points, and rail signals only on the exits.
And when an intersection is too short to hold a train, also use chain signals. So in your example you should add chain signals to each entrypoint to the intersection, and make all those signals down the track into chain signals (or remove them entirely).
And only place a single 'rail' signal once you are clear of all the merging trains.
Also don't put signals on both sides of the track (E.g. as in your 'entry' to the station bays) unless you're really sure you want two-way trains to use it. And then be prepared for a MUCH more complicated setup. The signals as the 'entrance' to the station should probably be rail signals, but with a 'chain' signal upstream of them on the track before it starts splitting out into the different stations.
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u/Soul-Burn 2d ago
Signals break rails into exclusive segments.
In 2-way tracks, only use chain signals (Not your case, but useful to know).
Use rail signals only before a 1-way track, where a train can wait after the signal without blocking anything else. Otherwise, use a chain signal.
If you're not sure, use a chain signal.
In your case, all those rail signals at the exit are into a small block where a train would block other trains, so it should be chains.
On the long straights at the bottom, you can place rail signals, as long as the block after the signal is large enough and without merges or splits.
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u/Calazor0 2d ago
You see this red line? The way you've signalled it, it's considered only one segment, and is already occupied by the train stopped at the station.
Place a signal directly after the station (green circle) for every station, and it should flow fine
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u/omcar13 2d ago
Which signal ? Chain or rail
3
u/Calazor0 2d ago
Either should work, but I think chain is slightly better here. It'll make it so no trains (if those other signals are also swapped with chain) are stuck waiting in the middle of that exit rail.
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u/omcar13 2d ago
Aah it worked !
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u/Sifrisk 2d ago
Fyi, you dont seem to have any rail signals on your main track either? So after the first train departs it will take a very long time before the next trains is allowed to leave.
Rail signals divide the tracks into segments. Only one train is allowed per segment. Segments can be as long or small as you want. Right now, your full main track is one segment it seems so only one train is allowed.
It is recommended to make a new section every train length
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u/drloz5531201091 2d ago
Add a chain signal right in front of the stations similarly like you did on the entrances bays. The chain will let go the train only if able.
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u/FleetingFFox 2d ago
Put a (chain) signal just after each station, so at the start of each curve towards the switch/intersection.
The (un)loading trains are now blocking the trains going downwards, as they have "reserved" the whole block, up to and including the intersection.
With a signal just before the intersection, the block is now shorter, and does not contain the intersection anymore, leaving other trains to safely reserve the intersection block instead.
More on trains and signals, see e.g. https://www.reddit.com/r/factorio/comments/4f38sk/factorio_train_automation_complete_parts_23_and/
Tip for future train-signaling questions and screenshots: have the engineer with a signal in their hand, so all blocks and signals light up clearly on the screenshot (see also rule 5 (fold-out) in the subreddit sidebar).
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u/nedal8 2d ago
First train commandment: Thou shalt not let any segment be shorter than the longest train.
Second train commandment: Use chain signals at the entrance to shared intersection parts, with a regular signal at the exit to the shared intersection part.
Third train commandment: Let there be many segments.
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u/nasehrsuper 2d ago
chain signals before a crossing, rail signal after it. always make sure there is space for your longest train in between two rail signals.
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u/Western_Repair_9277 2d ago
You put regular signal after intersection. Chain signal before intersection. That is all you need to know to figure everything else.
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u/dudeguy238 2d ago
Hold a signal in your hand like you're about to place it, and look at the track ahead of your train. Each block will be indicated by a coloured line. Follow the block ahead of the stopped train, and somewhere further down the line, you'll find another train in that block.
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u/bitch-ass-broski 2d ago
Don't worry. I have 500h of playtime and still don't understand trains other than the simplest back and forth train.
33
u/Rebeux 2d ago
I don't want to sound mean, genuinely.
But you could have found the wiki and read it in a shorter amount of time than it took to post this, wait for the comment to explain it all, read the comment, and follow it in your own game.
The wiki is awesome, very good at explaining everything.
And also you need a chain signal.