Factorio Train Automation
From Novice to Journeyman
by /u/Grays42
Introduction
Welcome to the Factorio Train Automation tutorials! This series is separated into three parts: Novice, Apprentice, and Journeyman. Each part will help you understand more complex workings of a functioning rail network in Factorio.
Before we get started, please make sure you are viewing in a slideshow format. Many of the demonstrations will not flow smoothly if you are scrolling with a mouse. For PDF readers, make sure you choose “single page” or “fit to page” view. If you are viewing on imgur, make sure you put “/all” at the end of the album address and choose “Fullscreen” at the right.��
Part 1: Novice
Let’s begin with Part 1! Before we dive into automation, you should first learn to run a train manually. Lay some track down, put down an engine, and move around. You’ll need to fuel it with this symbol: Enter gets in/out, W-A-S-D moves and turns. W is always forward from where the train faces.
�Set up the intersection to the right�and move around on it to see how�trains can navigate merges and�crossovers.�� Once you’re comfortable, let’s automate a train!
Stations, Signals, and Blocks
Part 1: Novice
To automate a train, first place a station along the�track in front of the train (can’t go backwards).
Notice the arrows? That’s � because stations can only be � approached from one direction.� Give your station a name by clicking on it.�Next, click the train and use the train scheduler to add the station with !�(You can delete it with ). will begin automation and will revert to manual operation. ( picks a specific station if you have a long list of them.)
Press to automate your train!
Stations, Signals, and Blocks
Part 1: Novice
And away it goes!� Easy, right? So what happened here?� The train actually did two things:�
So how does a complex train system meet these two objectives?
Stations, Signals, and Blocks
Part 1: Novice
Enter: the signal! When you place one, you’ll notice it’s one-way, like the station.
�
This is the first function of the signal: explicitly allows the train to use the track in that direction. Trains will never go through signals that don’t point the correct direction. Trains that can’t find a correct signal will not be able to find a path!
� A signal on each side of one spot allows trains to travel in � either direction along the track:
Stations, Signals, and Blocks
Part 1: Novice
The second function of a signal is to prevent collisions by breaking up groups of track into sections called blocks.
A block is any number of tracks crossing, merging, or splitting� that is bounded by signals.
If the block in front of the signal is If there’s something blocking�not obstructed, the signal turns green. the track, the signal is red.
Stations, Signals, and Blocks
Part 1: Novice
Here, you can see the blocks identified as boxes. Red boxes are obstructed and green boxes are available to be entered by trains.
Even though this second train isn’t even on the path to the station, it’s still in the third block. This prevents collisions!
Stations, Signals, and Blocks
Part 1: Novice
�Also, remember that our signals are one-way. If we put signals in the other direction, the lights on those will show occupied blocks in that direction.
Stations, Signals, and Blocks
Part 1: Novice
�Creating and managing blocks are the basic function of signals and a fundamental aspect of all rail networks.
Stations, Signals, and Blocks
Part 1: Novice
�
So what happens if we automate that train?
Stations, Signals, and Blocks
I want to get to that station.
Part 1: Novice
�Trains in Factorio will always move to the last available block on the path they have chosen. In this case, it will move to the end of the second block and stop until that block is clear.
Stations, Signals, and Blocks
The next block is occupied.
Part 1: Novice
Also, trains will always select the shortest route given multiple options.
Stations, Signals, and Blocks
Part 1: Novice
�If that route becomes obstructed somewhere, it will calculate a new path, as long as it has an option to change to a different block somewhere down the line.
Stations, Signals, and Blocks
Part 1: Novice
� But what happens if its final block is obstructed?
Stations, Signals, and Blocks
Part 1: Novice
The train will choose its best path and wait at�the final block for the obstruction to clear.
Stations, Signals, and Blocks
Part 1: Novice
Last example: We have two trains going in opposite directions, and a third line cuts across both. They should be able to safely cross at the same time.
Stations, Signals, and Blocks
Part 1: Novice
However, the center is all one block. If one train enters, the second has to wait.
Stations, Signals, and Blocks
Part 1: Novice
Any time you want to allow for multiple trains to pass, you can separate sections of track into their own blocks with more signals.
Like this.
Stations, Signals, and Blocks
it’s a trap!
Part 1: Novice
� Both can pass through at once. Everyone’s happy!
�*Actually, we have now exacerbated a This concludes Part 1: Novice!� huge problem. More on that next . (ignore that guy, he’s fine.)
Stations, Signals, and Blocks
*
Part 2: Apprentice
Welcome to Part 2 on your path from Novice to Journeyman! In this section, we will discuss intersections and chain signals.
In Part 1 we covered the basic components of a simple rail network: stations, signals, and blocks. Using these, you should be able to get trains from point A to point B fairly easily...assuming nothing else is moving in the network.
When you involve two, four, or twenty moving trains, things get considerably more complicated. But we will come prepared!
Let’s begin with the intersection we “fixed” at the end of Part 1.
Intersections, Chain Signals
Part 2: Apprentice
An intersection is defined as any group of crossings and merges where a train can encounter a train from a different line.
We set this up in Part 1, but we have a problem that we didn’t notice.
Intersections, Chain Signals
Part 2: Apprentice
We’re in the same situation as before,� with our train wanting to get to the station.
Intersections, Chain Signals
Part 2: Apprentice
This time, though, the train can’t get to its station.�There’s another train there--it could be out of fuel, loading ore, or just waiting.
Intersections, Chain Signals
Part 2: Apprentice
Our train doesn’t know that. It sees a green� signal and pulls out into the intersection.
Intersections, Chain Signals
Part 2: Apprentice
Now our train, who could have waited before the crossing,� is blocking the intersection...and another train is coming.
Intersections, Chain Signals
Part 2: Apprentice
So our northbound train is now also stuck, and the problem� just keeps getting worse as another train approaches.
Intersections, Chain Signals
Part 2: Apprentice
So now our problem with just one line is a problem for three, when those other two could have been moving freely even with one stuck situation. This kind of issue can quickly spiral into a deadlock, where every train is blocked by at least one other train. It all started when our first train entered the intersection and� couldn’t exit.
Intersections, Chain Signals
Part 2: Apprentice
From this example, we can come up with a rule we can enforce for all trains so that they never encounter a situation with a blocked intersection:�
Intersections, Chain Signals
Part 2: Apprentice
From this example, we can come up with a rule we can enforce for all trains so that they never encounter a situation with a blocked intersection:�
Golden Rule
Trains must never enter intersections�that they can’t completely exit.
Intersections, Chain Signals
Part 2: Apprentice
From this example, we can come up with a rule we can enforce for all trains so that they never encounter a situation with a blocked intersection:�
Golden Rule
Trains must never enter intersections�that they can’t completely exit.
�
The Golden Rule of intersections? Great! So...how do we enforce that?
Intersections, Chain Signals
Part 2: Apprentice
Enter: the chain signal!
Intersections, Chain Signals
Part 2: Apprentice
Enter: the chain signal!
Chain signals have all of the existing functions of regular signals.
Intersections, Chain Signals
Part 2: Apprentice
Enter: the chain signal!
� They make blocks and check for obstructions just like regular signals.
Intersections, Chain Signals
Part 2: Apprentice
Enter: the chain signal!
�
�However, they also look ahead to the next signal and turn red if it’s obstructed!
Intersections, Chain Signals
Part 2: Apprentice
Now let’s go back and re-signal our intersection. Our intersection encompasses every encounter between different lines.
Remember the Golden Rule! The train must only proceed if its exit block is clear.
Can I exit this intersection?
Intersections, Chain Signals
Part 2: Apprentice
We want to make decisions based on the exit blocks to the intersections, so we put regular signals on those. The behavior of those signals determines what everyone approaching the intersection is looking at.
Intersections, Chain Signals
Part 2: Apprentice
Now we want to address the incoming traffic and tell them to watch what happens to the exit block so they know whether it’s safe to enter the intersection at all. We do this with chain signals before every crossing.
Intersections, Chain Signals
Nope! That chain signal is red. My exit isn’t clear.
Part 2: Apprentice
Great! Now our intersection is completely safe to use without deadlocks.
The blockage cleared up and the train is ready to move forward into our completely safe intersection. Except...what if another train is passing?
Intersections, Chain Signals
Part 2: Apprentice
We’re back to our original problem that the intersection is one big block! The first time, we solved this by placing a signal in the middle, but that caused a deadlock. Fortunately, we now have a much better option.
Intersections, Chain Signals
Part 2: Apprentice
By placing a chain signal, not a regular signal, in the center of the intersection, we have safely split the eastbound and westbound lines so traffic can flow freely without causing deadlocks!
Intersections, Chain Signals
Part 2: Apprentice
Notice what happened here, though: This isn’t really a clear block! The upper block being occupied is telling the northbound line that it is not safe to enter, but allowing traffic through the eastbound line. This incredibly powerful behavior is what enables huge intersections to be safely used by many trains at once.
Intersections, Chain Signals
Part 2: Apprentice
From this we can deduce several Principles used to enforce the Golden Rule.
Intersections, Chain Signals
Part 2: Apprentice
From this we can deduce several Principles used to enforce the Golden Rule.
As previously discussed, the exit block is the only thing that a train heading to an intersection should be concerned about.
Intersections, Chain Signals
Part 2: Apprentice
From this we can deduce several Principles used to enforce the Golden Rule.
An intersection only begins when one line encounters another. At the moment this occurs, until reaching the exit block signals, every encounter must have a chain signal. We never want the train to be able to enter the intersection without taking into consideration what is happening at its exit block.
Intersections, Chain Signals
Part 2: Apprentice
From this we can deduce several Principles used to enforce the Golden Rule.
There’s a third intersection principle, but it’s actually outside the intersection, so we’ll cover it in Part 3 when we start having intersections interacting with one another.
Hint: it enforces the last part of the Golden Rule that requires you to completely exit the intersection.
Intersections, Chain Signals
Part 2: Apprentice
There is one unusual exception to these Intersection Principles: merges at the exit block of an intersection.
In both of these examples, three trains need to � merge into one exit block.
In the top example, we’ve put regular signals exiting � the intersection, whereas in the bottom, we’ve used � chain signals.
Intersections, Chain Signals
Part 2: Apprentice
� What we’ve done on top is turned the entire merge� into one giant exit block.
For the bottom, we have three chained blocks.
Intersections, Chain Signals
Part 2: Apprentice
� However, when any one of the three enters the exit block, both configurations perform exactly the same way.
This is because these three lines share a single output.� So for the case of exit merges only, the merges can be � combined into one large exit block.
(Note: This is a shortcut! Either� option will function just fine.)
Intersections, Chain Signals
Part 2: Apprentice
We have one last thing to discuss about chain signals before we move on. A train approaches a chain signal we will place here before the lane splits.
What color will it be?
��Hints:� ‣ A chain signal will act like a signal and be green if its block isn’t occupied.� ‣ A chain signal turns red if its block, or the block following it, is occupied.
However, one exit block is green, one is red. So which will the chain signal be?
Intersections, Chain Signals
Part 2: Apprentice
Neither. It turns blue!
What does that tell the train?
Intersections, Chain Signals
I need to see my next block, is it clear?
Um...maybe? It depends on which way you’re going. You figure it out!
Part 2: Apprentice
In Factorio, a moving train already knows the path it wants. A blue chain signal tells the train to check the next block in its individual path, because chain signals are global, not per-train. The chain signal itself has no idea which path the train wants to take, it just knows that some exits are obstructed and some aren’t.
Intersections, Chain Signals
Part 2: Apprentice
Next, we’re going to create a one-way spur coming off of a�block in an existing double-track network.
(Don’t worry about the “double-track” bit�For now—we’ll discuss network types in Part 3.)
Intersections, Chain Signals
Part 2: Apprentice
�First, we need to figure out where we will put our�connecting rails; we only need two, because there�are only two ways to get to the new line.
These need room for signals. (This will require�some trial and error.)
Intersections, Chain Signals
Part 2: Apprentice
�Now, we need to identify: Where is the intersection?
The only place the intersection actually exists�is the group of crossings and merges where�one train can encounter a train from a �different line. We have one of each.
Splits are not part of the intersection �because there is no chance for one train�to encounter an occupied block until�the next signal down the line.
Intersections, Chain Signals
Part 2: Apprentice
As we discussed before, we can consider this �merge at the exit to be one big exit block.
Again, this is an optional step. Chain signals will also�work exactly the same way, it will just make the exit�block further down the line.�
Intersections, Chain Signals
Part 2: Apprentice
(Enforcing Principle #1)
Now we need signals on the exit blocks.
One of them is already provided because�we’re modifying an existing block.
We could actually back this up to �just after the crossing if desired.�It actually does give us more room�in the larger network, so let’s go�ahead and do that.
Intersections, Chain Signals
Part 2: Apprentice
(Enforcing Principle #1)
Now we signal the northern exit block.
��
Intersections, Chain Signals
Part 2: Apprentice
(Enforcing Principle #2)
Finally, every time an interior rail encounters�a different line, it needs a chain signal.
In this case, there’s one other encounter in the intersection,�so we need a chain signal for each line leading to it.
Intersections, Chain Signals
Part 2: Apprentice
���And we’re done! That was easy, right?�Let’s try it out. Here come two trains.
Intersections, Chain Signals
Part 2: Apprentice
The westbound train arrived first, so the chain signal sees�an obstruction and stops our northbound train.
Intersections, Chain Signals
Part 2: Apprentice
Our train sees that its chain signal is green, indicating�that all the blocks through to the exit block�are unoccupied. It begins to move into the�intersection.
Intersections, Chain Signals
Part 2: Apprentice
The train crosses into the intersection, and now�occupies two blocks. This means we haven’t yet�cleared the lower, eastbound line.
In a real situation, this signal leading to the �exit block would turn red, because our northbound�train has reserved its path through the intersection�so it doesn’t get stuck.
Intersections, Chain Signals
Part 2: Apprentice
Now that we’ve cleared the bottom block, the lower�line becomes available for other traffic.
�
Intersections, Chain Signals
Part 2: Apprentice
As we move into the exit block, we still occupy�the last bit of our intersection, so we can’t�clear the westbound lane yet.
�
Intersections, Chain Signals
Part 2: Apprentice
We’ve cleared the intersection!
We have now restored traffic through the eastbound�and westbound lanes. Note the chain in the center,�though; it’s informing any new northbound�trains that it can’t use the intersection yet.
�Side note: As a rule of thumb, it is generally�preferable to place your exit signals as close to�the intersection as possible, so that exiting trains�clear mainline traffic faster. We did not do so in�every case for this example so that the signaling�demonstration is easier to understand.
Intersections, Chain Signals
Part 2: Apprentice
Here’s a complete summary of the process we use to signal an intersection:
And that’s it! Using those steps, based on the Principles, which enforce the Golden Rule, you can correctly signal any intersection. Remember that we’re missing one Principle; we’ll learn about it in Part 3, when intersections interact.
Intersections, Chain Signals
Part 2: Apprentice
Let’s do one more example before we finish.
Let’s signal a T-junction for a double-track network.
This may look more complicated, but�we can easily signal it using our same steps.
Intersections, Chain Signals
Part 2: Apprentice
First, we identify the intersection. This is the group�of encounters where trains from two different�lines can meet.
Intersections, Chain Signals
Part 2: Apprentice
Three of these encounters are merges at the�exits, which we can consider parts of the exit blocks.
We will not need chain signals here.
Intersections, Chain Signals
Part 2: Apprentice
Now we identify and signal our exit blocks.
����(Smaller for clarity, but normally�you’d want to push these back)
Intersections, Chain Signals
Part 2: Apprentice
Finally, we chain signal all other encounters between�different lines.
(Sometimes the positioning can be tricky�because you can’t place a signal in the�middle of a curved piece of track.)
Intersections, Chain Signals
Part 2: Apprentice
And that’s it! We’re done!
You now know where to place signals in any�intersection. This concludes Part 2!
You can now put intersections�anywhere you want to in your network!
—yes, I said that on purpose,� because we're discussing that� in Part 3. Go away.
Intersections, Chain Signals
it’s a tr—
Part 3: Journeyman
Welcome back to the final part of our series!
In Part 1 of this series, you learned the basic concepts of stations, signals, and blocks. In Part 2, you learned how to build intersections and use chain signals.
So far, everything we have done has been in a vacuum; we haven’t made a rail network and have had no discussion of how these pieces interact.
Now we need to tackle problems on a larger scale. Let’s get started!
Rail Systems and Networks
Part 3: Journeyman
Almost everything we’ve made so far has been one-way. Let’s discuss why.
Suppose I want to connect these two sections of�my network that are some significant distance apart.
(far apart)
Rail Systems and Networks
Part 3: Journeyman
We could use our intersection we made in Part 2,�but it will only allow for travel in one direction.
What if we want two-way travel?
Rail Systems and Networks
Part 3: Journeyman
We can certainly build it!�We just follow our intersection steps.
But, watch what happens when a train uses it.
Rail Systems and Networks
Part 3: Journeyman
The instant that the train enters the exit block,�the entire line becomes obstructed.
The other train has to wait on the mainline!
No amount of signaling can prevent this.�The entire line is one giant block.
Rail Systems and Networks
Part 3: Journeyman
Have you ever stopped at a construction light that turns � a two-way road into a one-way road?
That’s what a two-way rail is �like, except all the time.
So, never let two-way rails merge with�your network at more than one intersection.�(Two-way rails are fine for spurs and stations.)
Rail Systems and Networks
Part 3: Journeyman
Instead, every mainline (general transit line) in�your network needs to be at least two one-way lines.
This is called a double-track network.
Rail Systems and Networks
Part 3: Journeyman
It is also important to distinguish between two types of double-track networks: left-hand drive (LHD) and right-hand drive (RHD). There are no significant advantages or disadvantages for either, but the signaling for all intersections is completely inverted, so it is important to be consistent with whichever orientation you pick for your network.
Left-Hand Drive (LHD) Right-Hand Drive (RHD)
Rail Systems and Networks
Part 3: Journeyman
Next, let’s make a station in our network!
We’re going to use a standard one-way intersection�to get to a station off of a RHD double-track, just like we did�back in Part 2.
This time, though, it can’t exit; trains can only move forward.
Rail Systems and Networks
Part 3: Journeyman
In order to get back onto the mainline, we have�to choose a rail system. The two rail systems�available to choose from are:
‣ The terminal system*� ‣ The loop system��There are advantages and disadvantages to both systems.�����*The terminal system is often mis-stated as “double-header”, which means trains with two front engines.
Rail Systems and Networks
Part 3: Journeyman
The terminal system involves trains with�engines at both ends (actually called “top-and-tail” trains, but�we’ll just call them terminal trains).
Stations and spurs for this system are on two-directional lanes�and need a two-way intersection to get back on the mainline.
Rail Systems and Networks
Part 3: Journeyman
Terminal system implementations are more�compact than loop system implementations and involve fewer�blueprints, so most Factorio players tend to prefer them.
On the other hand, terminal trains accelerate more slowly due to�the added weight, requiring more engines for larger trains, which�involves larger blocks and larger stations. (Also, they’re ugly.*)�����*“2-headed trains have no style or soul. There, I said it.” -Zisteau
Rail Systems and Networks
Part 3: Journeyman
Loop system implementations require extra rails to allow the train to turn around.
They occupy� considerably� more real and require more� estate consideration for For these reasons, loops� pathing/deadlock tend not to be as popular� issues. as terminal systems� for general-purpose use.
Rail Systems and Networks
Part 3: Journeyman
Loop stations can also be implemented with a�second one-way intersection, but this�causes real estate problems as well.� In the end, the choice is�Also keep in mind that terminal yours, and since both work�trains can use loop stations, but on a double-track network,�loop trains (one engine) can’t back you can use either for your�out of terminal stations. more specialized stations.
��
Rail Systems and Networks
Part 3: Journeyman
�Now let’s talk block size. Small blocks are usually�fine, but in some cases can cause problems.
We’re going to use�this loop station as an example, �but this can happen on any We have an obstruction:�intersection if not managed There’s a train out of fuel on�properly. the eastbound mainline.
Rail Systems and Networks
Part 3: Journeyman
The train gets ready to get back onto�the mainline, and its signal is green�because its exit block is clear.
Rail Systems and Networks
Part 3: Journeyman
However, it’s too big to fit into the exit�block, and now the tail of the train�is sticking into the intersection.
This is a big problem because�another train is coming.
Rail Systems and Networks
Part 3: Journeyman
So what was once a problem for just�the eastbound line is now also a�problem for the westbound line,�which otherwise would have been�able to pass through.
Rail Systems and Networks
Part 3: Journeyman
To fix this situation, we have to�make our exit block bigger.�If the entire train fits, it will�prevent the westbound lane Naturally, moving around all of�from being blocked*. this track is very annoying, so it� would be better for this not to � happen in the first place.������*as long as this station is only used by one train. (See links in the epilogue.)
Rail Systems and Networks
Part 3: Journeyman
Well, good news! This just happens to be our final Intersection Principle!
Rail Systems and Networks
Part 3: Journeyman
Well, good news! This just happens to be our final Intersection Principle!
�
Rail Systems and Networks
Part 3: Journeyman
�Following these Intersection Principles for the Golden Rule will make your rail network almost* immune to deadlocks, as long as you have enough blocks.�
Rail Systems and Networks
Epilogue
So what’s next?
Well, now you know how to build deadlock-resistant* rail networks to connect all of your outlying outposts up to your main production hub.
There are going to be congestion concerns as your network gets bigger, but there’s a lot of subjectivity to how to handle those, which is outside the scope of our tutorial. There are all kinds of community resources, but now you have the tools to understand those pictures of giant intersections and how they work.
So congratulations on making it this far. You are now a Journeyman rail network designer! Now, only practice and patience will make you a Master.
External Links
*It is important to note that high congestion and multiple trains using some stations can still cause deadlocks. For more details, see Antaios’ guide to Stations, Junctions, and all things deadlock on the official forums. As as your network grows, you will need to learn techniques to manage congestion.
There are also a few mods that enhance the rail design and management experience that you might be interested in:
The Fat Controller is incredibly useful for remotely managing your trains.
Fully Automated Rail Layer (FARL) will place rail and blueprints while you � drive, making rail-laying in the late game much faster.
Resource Spawner Overhaul (RSO) spaces out ore patches and places rich� ore patches much further from the initial spawn, making rails necessary.
Credits
Special thanks to the redditors of /r/factorio who contributed advice, corrections, and suggestions in discussion threads while I was building the tutorial series:
/u/ak47_killstreak /u/Artorp /u/Calbrenar /u/chocki305�/u/chummchumm /u/cosmicosmo4 /u/DartonRejen�/u/freetambo /u/ichthyos /u/kann_ /u/maxcreeger�/u/Michael_Lewandowski /u/michaelthe /u/NihilRexGaming /u/para_lu�/u/qulqu /u/RedditNamesAreShort /u/rootnegative /u/strangepostinghabits�/u/TeamMisha /u/uffefl /u/w3y
And of course, thanks to the developers of Factorio for making a fantastic game!
Goodbye!
/u/Grays42