Destination station full behavior

[Flooraan]

TL;DR

Changing the action taken by trains when destination station is full to going to next step in schedule instead of freezing.

What ?

Currently, when a train finds itself in the "destination station is full" state, it freezes in place where ever it may be.
I suggest changing this behavior to acting the same way as if all destination station are disabled (ie, go to next step in the schedule)

Why ?

Currently, trains can find themselves stuck in the middle of tracks if destination station status changes. This is especially an issue when using multiple stations with the same name. I often find myself with trains stuck in the middle of the main "roads" because not enough station need that particular train. Making them resort to going to the next step in the schedule instead od freezing in place when all destination stations have enough trains heading to them would prevent this behavior.

[Loewchen]

Currently, trains can find themselves stuck in the middle of tracks if destination station status changes.

That just is not true. Stations getting full will have no effect on trains already on the way, you are doing something wrong.

[Flooraan]

Please refrain from calling me a liar. That is both unhelpful and rude.

You also provided no useful feedback beyond "you're doing something wrong". Again, unhelpful and rude.

Here are a few examples of the situation I am facing.
=======================================================================================================================
2 stations providing iron plates.

4 stations receiving iron plates.

the 2 provider stations have a train limit of 5.
the 4 receiving stations have a train limit of 2 due to high demand/distance making it impossible for a limit of 1 to feed local usage when going full speed.

Provider stations are always enabled.
Receiving stations disable themselves if enough plate is in the local inventory.

R2 requests iron plate. A train from each of the provider stations leave for R2.
R4 requests iron plate. More trains get filled at provider stations and leave to fill it up.

Trains arrive at R2. However, R2 isn't going full speed and 1 train was enough to fill inventory back up, so station disables itself.
Second train to R2 stays stuck in waiting area or on main track if it was still in transit, giving a purple error about the destination being full until R4 disables itself and no other R station are unable. If the train to R2 was still in transit, it might block the path to R4, making this a deadlock.

=====================================================================================================================

4 stations providing gears

8 stations receiving gears.

P stations have a train limit of 5.
R stations have train limit of 1.

Due to how the train station is setup on the receiver, I have some belts between the station itself and local storage. This can cause a small delay between the train leaving and the station disabling itself if the factory it feeds is off and the inventory from the train just barely makes the station cross it's turn off threshold.

When this happens and another R station is requesting the item at the time, any train that left for the station that disabled itself in the interval will stop where it is and display the purple message about the destination being full.
========================================================================================================================

In both these situations, I've had cases where a train being stuck on a track made the issue turn into deadlocks. Every single time, forcing the erroring train to go to the next step in it's schedule by hand solves it, but this requires manual intervention.

I've had this issue ever since "enable train limit" was introduced, but when building mega maps, it can become quite annoying to figure out why all your trains are jammed.

[Loewchen]

Receiving stations disable themselves if enough plate is in the local inventory.

That is what you are doing wrong and it has nothing to do with station limits.

[Flooraan]

Using the set train limit control on a train station to dynamically change how many trains are requested is basically an almost 100% certain way of triggering this condition. To the point that it's made me avoid it completely.

[Flooraan]

Receiving stations disable themselves if enough plate is in the local inventory.

That is what you are doing wrong and it has nothing to do with station limits.

Then how am I supposed to tell the train network I do not want a delivery?
And why does the option exist in the first place?

[Flooraan]

Also, please explain, beyond "you're doing it wrong" exactly why this is wrong?

[disentius]

Dynamic station limits. One way for unload stations would be to count the number of items in all unload chests and use a Decider combinator to set the trainlimit based on the # of items.
See the Factorio wiki for the differences between trainlimits and disabling stations. (trainlimits will never stop a train in the middle of a track, disabling stations will)
If you have more than 1 destination station with the same name, and thee train is already on its way, it will stop immediately when all stations are disabled. This is by design.

[Loewchen]

Using the set train limit control on a train station to dynamically change how many trains are requested is basically an almost 100% certain way of triggering this condition.

That still is just not true. Station limits cannot block a train already on the way to the station, if you can produce such a case you should report it as a bug.

Then how am I supposed to tell the train network I do not want a delivery?
And why does the option exist in the first place?

Use station limits, do not deactivate stations. Deactivating a stations has the same effect as deconstructing them, the station is completely gone and nothing can path to it, if all other stations are full then it cannot start to path to those and the train is stuck where ever it was when you deactivated the station.

[Flooraan]

https://ibb.co/VMLbxJJ image of the error message itself.

Extremly simplified blueprint that triggers the error message every time.

Code: Select all

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

Note that this is extremely simplified and intended specifically to produce the error message. It does generate the message at the train, but no error on the side of the toolbar. To trigger, send the train to the station without a condition. The whole point of that BP is to demonstrate the existance of the error message, not anything close to a "proper" way of doing things.

The BP below shows the behavior when a station is disabled and no more destination exists, as you say. You can see that instead of having the train provide the purple message at the train, the train goes back to the station with the circuit condition.

Code: Select all

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

Basically, I am suggesting making that purple error message behave the way you appear to say it should, by going to the next step in the schedule.

[Loewchen]

I'll move this to Gameplay help.

[Flooraan]

The fun of non-sync discutions!

I'm going to try the way you suggest. It may be my memory is faulty, but it sounds like I might need to read patch notes more. The behavior that had pushed me to do things this way was probably fixed sometime back and I had never tried it again.

While the blueprints show the difference in behavior, the root cause that had pushed me to using it when the train limit feature was first introduced appears to be gone.

Old dog lears new trick.

[Flooraan]

old dog cries looking at how many stations he as to change in his mega-map now that he found this wonderful news to be true. Not sure if happy or desperate, lol

[Tertius]

Just a few days ago, I researched (and tested) the train and station behavior thoroughly to prepare for building a larger base. I can confirm that there are two different behaviors between disabling a station and setting a station limit.

If there is a station with a train limit above 0, and trains are actively driving to that station, and while they drive the station limit is lowered (even to 0), all trains continue to drive to that station until they arrive there. Only new trains are not assigned to that station any more. But there is never a train stopped in the middle of the track.
If you disable a station while there are trains driving to that station, all trains driving to that station are immediately forced to repath. If they cannot find a path to a slot in some other station, they just stop where they are at that moment in the middle of nowhere. This is what you encounter.

So instead of disabling stations, set the train limit to 0. Trains already assigned will not stop but arrive at the station. To avoid trains arriving at a (nearly) full station, set the train limit to floor(free station capacity / train capacity).

However, you never fill a station with this, because the station capacity is usually not evenly dividable by the train capacity. The easy solution is to toggle train limit between 0 and 1, which is easy with a decider combinator. If you want as many trains as possible to fill the station, you can use a slightly different calculation: Don't divide by train capacity. Instead, do this:
First get maximum train limit L = floor(station capacity / train capacity)
Then get the divisor in the arithmetic combinator: Divisor = floor((station capacity - train capacity) / L)
Then compute the station limit by L + (station content / -divisor)

The divisor is constant, so don't compute it within Factorio but instead compute it by hand.
For a train with 4 wagons and 4 chests per wagon and ore (stack size 50), maximum train limit L is 4 * 4 * 48 * 50 / (4 * 40 * 50) = 38400 / 8000 = 4,8, floor is 4.
divisor is floor(38400 - 8000) / 4 = 7600

You need to count all chest content, divide by 7600, and subtract this from 4: this is your train limit. This way, the train limit goes from 1 to 0 exactly the moment there isn't any more one free capacity for a full additional train, otherwise "about" as many trains are allowed as there is space in the station.
I posted an example setup here: viewtopic.php?p=560419#p560419

[SoShootMe]

So instead of disabling stations, set the train limit to 0. Trains already assigned will not stop but arrive at the station. To avoid trains arriving at a (nearly) full station, set the train limit to floor(free station capacity / train capacity).

However, you never fill a station with this, because the station capacity is usually not evenly dividable by the train capacity.

I'm not sure why you think being evenly divisible matters. Did I misunderstand something?

"floor(free station capacity / train capacity)" means train limit changes from 0 to 1 when there is just space for a full train-load, from 1 to 2 when there is just space for two, etc. With good supply, the chests will be between full and one train-load less, minus the amount consumed in the train's journey time.

You need to count all chest content, divide by 7600, and subtract this from 4: this is your train limit. ... I posted an example setup here: viewtopic.php?p=560419#p560419

This is almost equivalent to "floor(free station capacity / train capacity)" but the train limit increases "too early" so you can end up with a train not able to fully unload. That said, it is unlikely in practice. Transition from 0 to 1 is off by one but later transitions have more "error", eg with a 4 wagon ore train and 16 steel chests, 4-floor(chest_total/7600) = 4 for chest_total in [6401, 7599], but this corresponds to space of [30801, 31999] meaning only 3 trains can fully unload.

[Tertius]

I'm not sure why you think being evenly divisible matters. Did I misunderstand something?

"floor(free station capacity / train capacity)" means train limit changes from 0 to 1 when there is just space for a full train-load, from 1 to 2 when there is just space for two, etc. With good supply, the chests will be between full and one train-load less, minus the amount consumed in the train's journey time.

Thanks for pointing out this (obvious fact) to me again. Hmpf. I just realized I made a mistake of thought - I thought too complex for a simple thing. Of course you just have to divide by train capacity and not by some lower number, if you divide the free capacity. Nothing more. I get all mixed up with these rule of three within rule of three, where the input is a rule of three for computing ratios, throughput, capacity, whatnot. Sorry for the confusion.

[astroshak]

Ideally you use a belt balancer before the loading station, and after the unloading station. This is to try to supply, or draw from, each cargo wagon chest set evenly, ideally resulting in even loading and unloading of the train. Also, this assumes you are using homogeneous loads (all iron ore, all green circuits, etc).

Loading station : wire up all the chests together, and send to the inlet of an Arithmetic Combinator. Take that input, divide by the capacity of the train, and send the output as L. You can wire that straight to the train stop to set the dynamic train limit, or you can wire it to a pair of parallel Combinator lines that go to the train stop. The first line would be a Decider Combinator, L < #, output L. The second line would be two Combinators: a Decider Combinator that says L >= #, output L = 1. Wire that to an Arithmetic Combinator that L * #, output L. Both lines get wired to the train stop. # is the desired maximum limit.

Unloading stations are similar. Simply add a Constant Combinator to the wire that the chests are all on, set it to the negative of the maximum capacity (if there are 4 chests for the 1-1 train, and the load is Iron Ore, 2400 * 4 * -1 = -9600 on the Constant Combinator). Change the first Arithmetic Combinator to the negative of the train capacity. The rest is all the same.

This dynamically sets the train stop limit such that whatever material is on hand determines how many trains can arrive. And as shown in the Loading station section, how to limit that to something lower. By default L is capped at 7 trains if you use 6 chests per wagon, so you may want that lowered by circuit logic or by using fewer chests. Or by using smaller chests.

[Flooraan]

Thank you all for the help.

Things work much better now. I'm just annoyed having to re-do so many stations, but that's factorio. Learn something, redo stuff.

I was probably basing my bias against doing it this way on some early bug from when I was playing experimental and the feature first came out. But this makes the feature so nice to use, it's worth it.

Unloading trains isn't an issue for me. The whole point of how I do my trains is that they don't come unless I can empty them.

[astroshak]

There is still a potential use for enable/disable stations. It just involves having exactly one train trying to service stations, with either multiple loading stations and exactly one unloading station (such as a train that goes to stations to pick up extra stuff such as wood/stone/coal, or deconstructed miners, etc.) OR multiple unloading stations and exactly one loading station (a “building” type of train). This train should have exactly two stops on its schedule : Loading and Unloading.

In this specific scenario, enabling/disabling the stations that the train services, while leaving the one that it needs to always return to on, works just as well and is simpler to set up. In this case, the supply side of a building train, or the delivery side of a junk collection train, must always be left on; it is only the various other locations that turn the station on to call the train and turn it off again while the train is present doing what it is supposed to be doing.

In all other circumstances, you should be using the Train Stop Limit. And do not try to combine the two, it tends to lead to problems.

[Tertius]

The crucial difference between deactivating stations and train limit is that if a station is deactivated, trains that have this station as destination are immediately repathed and never arrive at that station, while if a train limit is lowered, already pathed trains are still going to that station.

If it's important that due to some condition trains must not arrive at a given station under any circumstances, deactivating the station is the solution. Otherwise, train limit is the solution.

If using train limits, a little bit of proactive planning is required - usually planning ahead for one train, the one train that will still arrive even if the limit is lowered from 1 to 0.

Already pathed trains are still not pinned to a station under all circumstances. For example, consider a setup with multiple stations having the same name. In this scenario, if a train is currently going to a station but waiting at a chain signal for 5 seconds, it will repath, i. e. it will recompute the path to its destination. Since there are multiple stations with the same name, it is possible that this train will now get a different station as destination. Usually not, because the train got the nearest station as destination and it only got nearer, so it's still the nearest station. But if multiple trains were driving to that station, and one arrived there, there is a penalty in computing the new path for the occupied station, so the next nearest station may get elected if it's not too far away. It depends on the path cost from the current location of the train. It actually happens, I observed this behavior.
It's a mechanic that helps mitigating the "black hole" effect, where a station with a high train limit pulls all trains to it, and they queue up in front of it, while other stations that just increased their train limit from 0 to 1 will starve and not get any train.

May be that this mechanics was incomplete in the past, in a way that this repath was forced and the old path forgotten, and if the train limit was lowered to 0 in the meantime and no destination stations could be found any more, the train was suddenly stopped with destination full. I did not observe this behavior with current game versions, I assume this case is now explicitly handled and the old path sill used, as long as it is still valid and possible.