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I'm fairly new to the game and I'm trying to figure out more efficient ways for train lines. I'm thinking that the lanes on the west are better than north, the north side is taking up more space. Trains can just go inside the roundabout to switch from one side to the other.

I'd say maximum 4 lanes per side, going into a circle. Otherwise it gets too cluttered. 2 can drop off /pick off things, the 2 in the middle are to travel between intersections.

What do you think?

It is fairly uncommon to have 4 parallel tracks that are all 2 ways track. Most of the time out of the 4, like a road, people tend to build 2 track one way, and 2 track the other way.

It is more difficult what you did I would say because of the risk that trains deadlocks, when facing each other on the same portion if you failed your signaling or while changing it.

The signaling is tricky to master, but once you get the basics, it's can be easy to use and learn to make more precisely what you want. Your signaling works atm, train wait untill the junction is free to get in.

For now your roundabout is one single block, this means only 1 train can use it at a time, and the 2nd train will enter the roundabout when the 1rst is away from the roundabout block ( past a signal).

The good side is a train can take it clock wise or counter clock wise. This makes it so that any lengh of train can use the roundabout unless they want to exit from where they enter( in this case very long train will crash on themselves).

The less good side is if you want more than 1 train to use the roundabout at the same time, say from the left, one wants to go up north, the other one straight to the right of the map. They will do it one after the other which can become an issue for throughput.

One other problem that might occur is if 2 trains wants to exchange their place and wait at the junction( forever). ( we can't know the schedule)

What are you refering to when you say efficency ?

The space it takes on the map ? The number of rail ? The number of train that can go throught in 1 minutes ?

I am not sure i understand well your question or plan for future, but as a general rule, you want your junction block to be well divided in small portion.
This way trains are more reactive, they know faster when they can go.

In this particular case it's difficult because the tracks are 2 ways. If you try and cut the block in smaller part in the north; one train arriving from the north can block train coming from the left and willing to go north if they don't wait completly outside the junction which makes it longer for trains to clear it since during the time trains clear that extra little distance no other trains can use the roundabout.

The signaling on the left side is closer to the roundabout it is more "efficient" because trains leave the intersection faster, the one on the right side and south are even closer.

One thing you can add on this one is a pair of chain signal on each side of each diagonal portion of the round about.

This will cut the big block of the junction in 4 blocks corresponding to each side. This way one train from the left can use the roundabout to go north at the same time as a train from the south use the junction to go right.

Their path does not collide but trains can only know if the signaling cut the junction in smaller block. If not the pathfinding makes them wait until the block is not occupied. If the junction is multiple block then the pathfinding recognize the situation where trains does not need to use the same.

You always have a trade-off anyway, the smaller the junction, the less space for signaling,like when it's very close where you have the 4 X on the 4 sides, you can't signal on the inside, but it's not a big deal because the portion is so small that a train will leave it fast, in some case you will want to make the room for signaling because it would allow the pathfinding to be smarter.

If you need to signal and it makes the junction seems too big. You have the option to make it even bigger and leave room inside the junction for trains to wait, or really, to fit a regular train signal, so that a train is prevented to enter the junction unless the first 1/2 is open. Like a waiting spot in crossroads when the road is really wide.

We don't know the size of trains you are using, if they are 1 Loco and 1 Cargo wagon, it is not the same size of buffer than if your trains are LLLCCCCCCCCC.

Depending on their lengh, the number of train expected, and from where and to where they will enter/exit the junction, you might want to make room for signaling, to allow horizontal trains of opposite direction to use the junction at the same time for example.

I didn't expect a novel of a reply but I appreciate it. It would be better to have all one way tracks but I couldn't figure out how to force trains to do it. Most areas simply do not have room for the train to turn into a circle and the tracking required would be MASSIVE, as well as me having to constantly keep track in my head which way which track goes, and adding stations in order to force trains to align one way. The easy fix for all of this would've been if the developer implemented ''no entry'' signs that can be attached to tracks. Letting trains go both ways seemed like the easy and simple fix. Your suggestion is further solidified by the fact that in cities (in real life) with high traffic, the council converts roads to one way because it's more efficient.

''One other problem that might occur is if 2 trains wants to exchange their place and wait at the junction( forever). ( we can't know the schedule)''

yes, which is why I have to manually observe if it happens, and when it does, I have to add tracks to avoid the *chance* of that happening. It's all a matter of pure luck. If the roundabout had 10 entries and 10 exits, this would never happen since the train can easily take a different route. But with 6 trains and only 2 exits/2 entries, the chance is high. I also noticed that adding more frequent roundabouts rather than having long distance between the roundabouts would lower this from happening.

I don't know how I can make this design into small portions. That's why I'm here. The T junction in the image is more like you mean but I didn't personally like it. It's much bigger and much less flexible.

''One thing you can add on this one is a pair of chain signal on each side of each diagonal portion of the round about.'' I don't understand what you mean. Add signals inside the roundabout? I assume that doing it will filter what the train is looking for... right now, it says ''only one train can entire any portion of the roundabout no matter which way they come from or go to'' but adding signals in corners means that the train will check only if their needed portion is clear or not. So it adds the posibility of 2 trains being inside? Am I getting this wrong? Because I thought adding the chain signal in the middle was 100% redundant. Or you mean to make the roundabout big enough so that an entire train can wait inside it? That seems like breaking my rule that ''no train shall ever wait inside an intersection'' hence why in real life almost no intersection is like that.

Sorry for not mentioning earlier, my trains are 1 locomotive+2 identical wagons+1 locomotive, standard to be kept at all times for all trains regardless of what they do.

But again, I don't understand how you could possibly do it so that 2 trains can use the same roundabout without the risk of a deadlock.

Thanks for your comment

btw adding an extra track on the corners would help easy congestion, wouldn't it?

You can simply have two-headed tracks use one-way tracks. That way you can use the compactness of a a two-headed station with the scalability, ease of design and performance of one-way tracks. Disadvantage is if you use trains with multiple wagons where the wagons are not just all carrying the same items you will have to keep that in mind since the order the wagons arrive in in the station can vary, but if you are just doing 2 wagons of iron or electronics or bullets or whatever that does not matter.
For remembering which tracks go which way: Consistently do righthand drive (or lefthand drive) and stick to one. And the signals are also telling you in whch way the trains on them drive anyways.

Here is a two-way-one-way-track transition. Left lower rail is where the train comes in from the larger network, right is the two-way track to the station (well in this case it's a bit more complicated but it could just be the station) and left upper is where it goes to the larger network again.
https://steamcommunity.com/sharedfiles/ ... 1795539100

How do you generally make the trains turn around then? Take these stations that I have for example in the photos. The fundamental problem is that I need tons of space and it's not flexible.

Most of my stations are in fact crammed up like that.

llVIU wrote: ↑

Sun Jul 07, 2019 3:47 pm

How do you generally make the trains turn around then? Take these stations that I have for example in the photos. The fundamental problem is that I need tons of space and it's not flexible.

Drive forward to get out. In my case, normally by having the station be one or more rails aligned with the direction of travel, so if they are coming off an east-west line, they go back to the same east-west line. A loop, as it were. The pathfinder doesn't like driving through stations if it can avoid it, so it'll not get abused as a shortcut or anything.

Honestly, though, to the original question in your post: I'm pretty confident the best way you could improve the efficiency would be to radically simplify your designs. Two lanes, one direction of travel on each, either left- or right-hand-drive. Avoid complex intersection design, and prefer to avoid having to route many trains through one place. If necessary, split into multiple separate rail lines instead of sharing infrastructure.

Your challenge seems to be that you are hurting for some sort of efficiency, and given you reached for four tracks, I'm assuming it is not so much throughput as "reducing contention" so that trains don't get held up. Unfortunately, several things in your comments - like "inside track for ..." - are not going to be respected by the pathfinder system. It'll use whatever seems convenient at the time, and unless you have enough "buffer", enough space that the trains can't ever possibly both wait for the other, more tracks will make your situation worse, not better.

A simpler system, perhaps counterintuitively, will mean far less trains getting into those sort of conflicts to start with. Your overall performance will actually improve.

Finally, you comment that you "need tons of space", which is ... the nature of trains, really, both in-game and in the world. They are not great at short distance transport, and they are not very flexible. That is why "light rail" and truck/car transport dominates those, moving things from the inflexible train loading point to the final destination.

The game gives you around 10,000 miles in every direction from your starting point. You have plenty of space, use it. Don't be afraid of train track sprawl between parts of the factory, and don't try to use trains where belts, or bots, are the "last mile" delivery solution to move the stuff the trains delivers to the consumers.

I'm pretty confident that by simplifying, you will find many of the annoyances you describe here go away.

Why would trains need to turn around? If you really need to you can just have a circle in your rails like here: https://steamcommunity.com/sharedfiles/ ... 1795679522

And your stations could then look like this
https://steamcommunity.com/sharedfiles/ ... 1795679676
or this
https://steamcommunity.com/sharedfiles/ ... 1795685428

of the stations you showed 1&4 are already compatible with a 1 way network, 3 only needs an additional rail connecting it to the circle in the other directions and 2 can be plugged into the network after the 2-way-rail part with the adapter I showed earlier. Unless there are more than 1 train servicing 2, in that case you'd need some additional waiting bays.

llVIU wrote: ↑

Sun Jul 07, 2019 12:56 pm

Most areas simply do not have room for the train to turn into a circle and the tracking required would be MASSIVE

Railway setups usually take lots of space. Balloon loops (the technical name for turnaround tracks at stations) are much, much smaller than high-throughput 4-way railway junctions. That you are complaining about the amount of space required for one tells me that you are making your railway system much too small for it to really be effective. In fact, you already have lots of railway entities that are the size of balloon loops--each of your roundabouts is such a balloon loop. If you design your system from the start with balloon loops in mind, it's not that difficult. For example, in the second image of your last post, instead of a vertical loading station, I would have built a horizontal station at the top of an oval balloon loop; there's more than enough space there for such a station.

There are several problems with your system, so let's take them one at a time.

As noted, your mainline track really, really, really should be using one-way tracks. Designing large systems with two-way tracks that can support more than one train using them is possible, but it's a much more difficult skill, and appears to be above your current skill level. The station tracks themselves can remain two-way track, if you have double-headed trains, and there's a few ways you can hook these stations up to the mainline track. You can terminate a two-track (one in each direction) into a two-bay station by placing a crossover junction and signaling it appropriately (i.e., the stations each have a pair of signals protecting it, while the one-way tracks each have signals only on one side). Alternatively, you can build your station as a T-junction of 1 track onto the 2-track mainline. Of your latest images, the first station is already correctly set up for using a 2-track mainline; the second image needs you to extend the track of the bay with the train in it to the other track, and then reuse part of that track as a crossover junction for other bay; the third station is technically already capable of supporting 1-way mainlines, but you ought to put in an entrance/exit from the clockwise direction so that your roundabouts become one-way, like the fourth station which is itself a correct way of hooking things up.

Once you're using one-way tracks, the next problem that is going to become readily apparent is your junction issue. The throughput of a railway system is going to be determined by its weakest link, and junctions are inherently much, much lower throughput than their surrounding track. From what I can gather of your railway system, your system is not so much describable as a set of mainline tracks with junctions between them but a set of junctions with queues to enter them. You probably have too many junctions, given your comment "I also noticed that adding more frequent roundabouts rather than having long distance between the roundabouts would lower this from happening." Your junctions are also of poor performance: they only permit one train to enter them at a time. What you'll need to do is to pick a direction for trains to go in (counter-clockwise for right hand drive, clockwise for left hand drive), and then use chain signals to divide the roundabout into four quadrants. This would allow any pair of trains going straight to continue through the intersection without conflict. At the same time, you can also remove the crossovers immediately before the roundabouts to make it impossible for trains to go through the intersection in the wrong direction--you only need crossovers if you put the station immediately on the roundabout.

llVIU wrote: ↑

Sun Jul 07, 2019 12:56 pm

''One thing you can add on this one is a pair of chain signal on each side of each diagonal portion of the round about.'' I don't understand what you mean. Add signals inside the roundabout? I assume that doing it will filter what the train is looking for... right now, it says ''only one train can entire any portion of the roundabout no matter which way they come from or go to'' but adding signals in corners means that the train will check only if their needed portion is clear or not. So it adds the posibility of 2 trains being inside? Am I getting this wrong?

You are correct. Like on the picture where chain signal are on a roundabout both inside and outside. After you do it, when holding a signal it will show different colors for blocks, and it may be visually easier to understand what I meant and why it's not redundant. Then yes, the pathfinder will be more precise and a bit faster to let other train enter the junction when the first one is 1/2 done or even let 2 train when they use differents blocks.

It is probably easier to design a new network with new ideas in mind rather than retrofit the one you already have.

But by doing so you will notice every details that matters in the process.

The equivalent of a "no entry" track, is when you only signal on one side of the track (it become the "right" side ). It shows some white or yellow triangle to indicate the direction. This will prevent any train to use the path in the wrong direction and will make a one way track. This should reduce significantly the possibilies of deadlock in junctions, since entries and exits would be separate tracks.

Then following the "right hand drive" or "left hand drive" makes sense since your parralel tracks are one way, you can picture the tracks in a junction as the trajectory of cars in a T intersection, or a roundabout, or a 4 way junction, or whatever you feel is needed.

Train with loco on both sides and the kind of station you have already with no loop at the end are to my opinion the most space efficient way to do it. But it is not the most straightforward to scale up when you want more trains. Effiency in traffic very often comes at the cost of space and number of tracks.

mergele wrote: ↑

Sun Jul 07, 2019 5:16 pm

Why would trains need to turn around? If you really need to you can just have a circle in your rails like here: https://steamcommunity.com/sharedfiles/ ... 1795679522

And your stations could then look like this
https://steamcommunity.com/sharedfiles/ ... 1795679676
or this
https://steamcommunity.com/sharedfiles/ ... 1795685428

of the stations you showed 1&4 are already compatible with a 1 way network, 3 only needs an additional rail connecting it to the circle in the other directions and 2 can be plugged into the network after the 2-way-rail part with the adapter I showed earlier. Unless there are more than 1 train servicing 2, in that case you'd need some additional waiting bays.

in your first pic, why did you put your rail signals like that and which way is going where? It doesn't make sense to me.

How are my stations compatible with a 1 way system, the train can go back on either tracks so it's clearly not a 1 way. I would have to completely redo the whole track system outside the pics. And I don't understand how I would force it to use one track then have it come back through a different, specific track.

mmmPI wrote: ↑

Sun Jul 07, 2019 6:15 pm

llVIU wrote: ↑

Sun Jul 07, 2019 12:56 pm

''One thing you can add on this one is a pair of chain signal on each side of each diagonal portion of the round about.'' I don't understand what you mean. Add signals inside the roundabout? I assume that doing it will filter what the train is looking for... right now, it says ''only one train can entire any portion of the roundabout no matter which way they come from or go to'' but adding signals in corners means that the train will check only if their needed portion is clear or not. So it adds the posibility of 2 trains being inside? Am I getting this wrong?

You are correct. Like on the picture where chain signal are on a roundabout both inside and outside. After you do it, when holding a signal it will show different colors for blocks, and it may be visually easier to understand what I meant and why it's not redundant. Then yes, the pathfinder will be more precise and a bit faster to let other train enter the junction when the first one is 1/2 done or even let 2 train when they use differents blocks.

It is probably easier to design a new network with new ideas in mind rather than retrofit the one you already have.

But by doing so you will notice every details that matters in the process.

The equivalent of a "no entry" track, is when you only signal on one side of the track (it become the "right" side ). It shows some white or yellow triangle to indicate the direction. This will prevent any train to use the path in the wrong direction and will make a one way track. This should reduce significantly the possibilies of deadlock in junctions, since entries and exits would be separate tracks.

Then following the "right hand drive" or "left hand drive" makes sense since your parralel tracks are one way, you can picture the tracks in a junction as the trajectory of cars in a T intersection, or a roundabout, or a 4 way junction, or whatever you feel is needed.

Train with loco on both sides and the kind of station you have already with no loop at the end are to my opinion the most space efficient way to do it. But it is not the most straightforward to scale up when you want more trains. Effiency in traffic very often comes at the cost of space and number of tracks.

So in this picture, judging by the signals I have, the train will simply refuse to enter the track without signal? I don't understand why it would work like that. What's stopping it from entering the track without the signal?

Also, I made another interection, 1 way, how would this work?

llVIU wrote: ↑

Sun Jul 07, 2019 6:51 pm

So in this picture, judging by the signals I have, the train will simply refuse to enter the track without signal? I don't understand why it would work like that. What's stopping it from entering the track without the signal?

Trains refuse to path into a block without a signal protecting the entrance. So if there's only a signal on one side of track, that track becomes a one-way track. The UI even guides you to this principle: once you put signals on one side of the track, the slots for signals on the other side disappear except for the slots that would turn it into a two-way track. If you don't see those slots (and there's room to put signals there), then that means that the game thinks that the track is a one-way track.

As for your intersections: both of them are functionally correct, but they suffer from the limitation of only allowing one train to pass through them at a time. The first intersection is too cramped to put any signals in. while the second one does have room for signals to break it up into multiple blocks.

On the first picture, it's easy, there are no tracks that could make a train go in a wrong direction. You have made the entrance and exit one way. The arrows are correct. If you manually place a train trying to enter from an exit, the train will tell "no path", even if there IS a path, the train cannot take it, the signal give a direction to the tracks, and for the train it is the same thing as no track at all.

It is different than just an occupied track, where the train wait, it is a forbidden path, the train will try to look for another one, and if he can't find, it will freeze where it is and say "no path".


Now for the second picture It is a bit messy but hopefully it explains why the train will not take a wrong path.

It is true that there are rails that trains could take and end up in the wrong exit. But the signal you have placed give a direction for the whole block. It will not let the train even consider those a possibility.

This means when a train enter the roundabout, it does it by crossing a signal. This signal will give the direction of the tracks for the next block until another signal.

If a trains want to turn left, with your signal it will take the short way, and turn left directly after the chain signal. going clock wise.

If a train wants to turn right, it will take the short way too, and turn right directly after the chain signal. going clock counter wise.

Now if a train wants to go straight, he has 2 options, the longer 1/2 circle, or the short 1/2 circle. ( extend the path to finish the circle and it is the U-turn).

It is now both clockwise and counter clockwise but never at the same time since it is only 1 block, when a train enters, it decide and the orientation will stay until the train leave the block, next train can pick up the opposite.

If you were to place signals inside the roundabout where there are 2 opposite red arrows, it will make it clockwise, if place signals outside the roundabout , the opposite.

And this, at all time. This means trains that wants to turn left will do the long circle and take the 3rd exit every time if you make it counter clock wise like in (most) road roundabout when you drive on the right side.

It will also cut the whole roundabout into 4 pieces, Top right bottom left.

This would allow a train from the bottom to turn right to the right side of the map at the same time as a train from the north doing the same easy turn, this time with mirror it would go on the left side of the map.

This would also allow one train to turn left, and the second one to turn right, would be a little faster to enter, it will not wait for the first one to completly leave and take the 3rd exit, it will wait for the first one to clear the first 2 blocks, not the full 4. since by the time the first train has done 1/2 circle, the second one can safely do 1/4 and not collide.


The signaling will be a bit redundant for orientation only, but it allows the previous chain signal to turn blue faster rather than staying red.

It wouldn't be soo long if i could express myself better in english sorry that you have to be my trainer haha , i hope at least i'm of some help

These 1-way intersections would work perfectly fine. They hamper throughput a bit since they allow only 1 train in the intersection even if those don't collide, but that is a refinement step that can be done later via more space and liberal use of chain signals.

To explain the rail in my first pic. It's a righthand drive system, if we go alnog the top from left to right the rails we cross are: The rail on which trains drive towards the bottom right - the rail on which trains towards the top left - a rail towards a station, but from what is in the pic it could also be just a second rail on which trains towards the top left.
Trains coming from the top left can use the ring to cross over into the track leading to the top left again (specifically they probalby want to go the the station there), while trains coming from the lower right can use the ring to go back to the lower right if they want. The signals in the ring are there to break up the block that would otherwise engulf the entire ring and block trains that don't want to use the ring passing each other at that point. The ring can only be used in an anti-clockwise direction since it is the only direction it will ever be reached in so for consistency I made it a 1-way as well. Why there is a chain signal instead of normal signal top left I am not sure myself, probably a leftover from a earlier time. (Throughput could be improved a bit if instead of a ring I had the U-turns as a X, but it's minimal and I like the asthetic.)

You would have to redo your entire signaling and maybe some connections and some station adjustments, but most of your track could stay as it is. For example on your 3rd station (the one with copper): (I am assuming for the following righthand drive, if you choose to you lefthand adjust directions accordingly) If you signal the circle before it to be usable only in a anti-clockwise direction the train could come in from the circle through the lower rail, enter the 2-way rail and station and load, then leave again through the upper rail and now it's again on the 1-way rail network (the ring), driving in the correct direction. It can never leave the station through the lower rail since then it would collide with a signal on it's left side that is not paired with a corresponding signal on it's right side, therefore such a path will never be chosen (to be precise, such a path does not exist in the first place). (Depending on where you set the signals in the circle and if you emove the crossing rails before it it may also never enter from the top, but that would be irrelevant if it did)
Similar to your 1st staion. You can enter the station from the ring following the normal direction and you can leave the station and enter the larger network in the correct direction, therefore it will work as-is if you convert your netwok to 1-way rail.

ok I didn't knew that trains refuse to enter a track if there is a signal on their left but not their right... my fault, sorry. By that logic, this should work fine (See pic 1 and 2) As for mergele... shouldn't it be like this though? With a chain signal at the entrance, so that trains only go in if it's clear in the 2nd half of the circle as well? so tl;dr middle signals is so that a north and south train can both go forward without distracting each other.

llVIU wrote: ↑

Sun Jul 07, 2019 10:33 pm

As for mergele... shouldn't it be like this though? With a chain signal at the entrance, so that trains only go in if it's clear in the 2nd half of the circle as well? so tl;dr middle signals is so that a north and south train can both go forward without distracting each other.

3341.jpg

All signals in the middle of an intersection (in addition to entry signals) should be chain signals. So when you're adding signals to break the intersection up into blocks, all the new signals must be chain signals to prevent gridlock.

llVIU wrote: ↑

Sun Jul 07, 2019 10:33 pm

As for mergele... shouldn't it be like this though? With a chain signal at the entrance, so that trains only go in if it's clear in the 2nd half of the circle as well? so tl;dr middle signals is so that a north and south train can both go forward without distracting each other.

Actually yes you are correct, there is a possibility for a deadlock here that I have missed so far.

I added some Chained signal with paint at the end of the reds lines. Not sure the game would allow you to place them in those little spot, on a curve.

This would create 2 blocks, a yellow one and a green one, instead of only 1 block. Allowing train to join orange sides throught different block, at the top the yellow block will be occupied, not the green, so at the bottom another train can enter the green one.

Now chained signal check the next regular block, so if you have two of them in a row, they check that both segment are clear before going.
Chaining signals on a longer distance can reduce traffic since they wait further, but it allow to make the trains waits where they don't block the junction which is overall wait better most of the time.

In this case you can have a train on the green block. The circled chained signal on the left would be red. The First chain signal on the top would be blue.

This means it would not let train go through the yellow block if they were to go to the green block after, like a red for those so they wait outside. But it will let train use the yellow block to go top left if any of the regular signal is green at the exit, like a green for those.

thanks for all the comments, the factorio community has been more helpful than any other forum I've been on in 20 years. And this was my first post.

Is there a thread where people post their factorio track design including junctions? I want to see what kind of designs other people came up with.

Also quick question, what is your general rule on the distance between your tracks (paralel distance)... I give it 4 squares of empty space because that's the minimum required to quickly change tracks, and also leaves plenty of space for putting belts/pipes in between to turn, train station stops, and loaders for coal. See pic. Are there instances where you guys cram up even more tracks or do you leave more empty space than me for some reason?

viewforum.php?f=194
4 spaces is probably a good number if you do things methodically.