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[[File:transport_belt_preview.png|right]]The belt transport system is the first system the [[player]] will use to transport items from place to place. It, along with [[Railway|trains]], and [[Logistic network|Logistic robots]], makes up the systems of item transportation in Factorio.
  
The belt transport system is the first system the [[player]] will use to transport items from place to place. It, along
+
Belts specifically are used to transport items and run without using energy. Belts can also interact with other moving entities such as [[player]]s, [[vehicle]]s and [[enemies]], also allowing for faster or slower movement speed.
with [[Railway|trains]], and [[Logistic network|Logistic robots]], makes up the systems of item transportation in
 
Factorio.
 
 
 
Belts specifically are used to transport items. By developer design, all transport belts run without using energy.
 
This is to reduce complexity and allow belts to be placed outside of electricity networks.
 
 
 
Belts can also interact with other moving entities such as [[player]]s, [[vehicle]]s and [[biter]]s, also allowing for faster or slower movement speed.
 
 
 
== All types of Transport belts ==
 
 
 
Below is a chart of all the Transport Belts present and available for use in Factorio.  
 
  
 +
== Belt tier overview ==
 +
[[File:Transport_belts_speed.gif|300px|thumb|top|Animation showing the three types of belt and their speed (from top to bottom: regular belts, fast belts, and express belts).]]
 +
There are 3 different tiers of belts available for use. The [[transport belt]] has a yellow color and is the slowest, as well as the cheapest to craft. The next tier up, the [[fast transport belt]] has a red color and is twice as fast as the standard transport belt. The [[express transport belt]] is the final tier. It is colored blue and is three times faster than normal belts, or 1.5× faster than red belts.<br>
 
{| class="wikitable"
 
{| class="wikitable"
! [[Transport belts]] !!  [[Underground belts]] !!  [[Splitters]] !! Max. throughput (Items per [[game-second]]) !! Needed research
+
! [[Transport belts]] !!  [[Underground belts]] !!  [[Splitters]] !! Max. throughput<br>(Items/[[Time#Seconds|second]]) !! Needed research
 
|-
 
|-
| {{Imagelink|Transport belt|Transport belt}}
+
| {{Imagelink|Transport belt}}
| {{Imagelink|Underground belt|Underground belt}}
+
| {{Imagelink|Underground belt}}
 
| {{Imagelink|Splitter|Splitter}}  
 
| {{Imagelink|Splitter|Splitter}}  
| 13.333
+
| 15
| [[Logistics 1]]
+
| [[Logistics (research)]]<sup>1</sup>
 
|-
 
|-
| {{Imagelink|Fast transport belt|Fast transport belt}}
+
| {{Imagelink|Fast transport belt}}
| {{Imagelink|Fast underground belt|Fast underground belt}}
+
| {{Imagelink|Fast underground belt}}
| {{Imagelink|Fast splitter|Fast splitter}}  
+
| {{Imagelink|Fast splitter}}  
| 26.666
+
| 30
 
| [[Logistics 2 (research)]]
 
| [[Logistics 2 (research)]]
 
|-
 
|-
| {{Imagelink|Express transport belt|Express transport belt}}
+
| {{Imagelink|Express transport belt}}
| {{Imagelink|Express underground belt|Express underground belt}}
+
| {{Imagelink|Express underground belt}}
| {{Imagelink|Express splitter|Express splitter}}  
+
| {{Imagelink|Express splitter}}
| 40.0
+
| 45
 
| [[Logistics 3 (research)]]
 
| [[Logistics 3 (research)]]
 
|-
 
|-
 
|}
 
|}
 +
<sup>(1)</sup> Only for the underground belt and splitter. The basic transport belt is available at the start of the game.
  
&nbsp;See '''[[Transport_belts/Physics|Physics of Transport Belts]]''' for more detailed information.
+
Regardless of the belt tier, a fully filled straight transport belt holds 8 items in total. For more information on this, see [[Transport belts/Physics]] and [https://factorio.com/blog/post/fff-276 Friday Facts #276 - Belt item spacing].
 +
{{clear}}
  
 +
== Belt mechanics ==
  
 +
=== Merging and un-merging belts ===
  
== Tiers of belts ==
+
Belts of all tiers have 2 lanes for items to ride on. This allows for either a double flow of one material, or to transport two different materials on the same belt. Mixed belts can be beneficial for
 
+
smelting ore, or producing items with many different ingredients such as [[Utility science pack]]. The belt can be unmerged using a splitter filter. It is also possible to unmerge a mixed belt by using underground belts since an underground belt will block half of the belt.  
[[File:Transport_belts_speed.gif|300px|thumb|top|Animation showing the three types of belt and their speed (from top to bottom: regular belts, fast belts and express belts).]]
 
There are 3 different tiers of belts available for use. [[Transport belt|The basic type]] has a yellow color and is
 
the slowest. [[Fast transport belt|Next tier up]] has a red color, and is twice is fast as the yellow tier. [[Express transport belt|The third]] and final tier is colored blue and is three times as fast as the basic belt.
 
 
 
 
 
{{clear}}
 
 
 
== Mechanics of belts ==
 
 
 
This section describes the mechanics of transport belts.
 
  
=== Merging and un-merging belts ===
+
[[File:Transport_belts_2_lanes.gif|top]]&nbsp;&nbsp;&nbsp;[[File:Transport_belts_unmerge.gif|top]]
  
Belts of all tiers have 2 lanes for items to ride on. This allows for either a double flow of one material, or with
+
Belts going across a splitter will have items from the splitter moving to one side of the crossing belt.
some careful setup, transporting two different materials on the same belt. Mixed belts can be beneficial for
 
smelting ore, or producing items with many different ingredients such as [[science pack 3]].  Un-merging a mixed belt is
 
fairly easy too, since an underground belt will block half of the belt.  
 
  
[[File:Transport_belts_merge.gif|300px|top]]&nbsp;&nbsp;&nbsp;[[File:Transport_belts_unmerge.gif|300px|top]]
+
[[File:splitters_to_one_side.gif|top|Splitters moving objects to just one side of a belt.]]
  
Commonly, merging and un-merging is done by using a [[splitter]]. The trick in the second picture is better described in the '''[[Belt_transport_system#Underground_Belt_as_blocker_of_one_side_of_belt|Underground Belt]]''' section.
+
Commonly, merging and un-merging is done by using a [[splitter]]. The trick in the second gif is better described in the '''[[Belt_transport_system#Separating_belt_lanes|underground belt]]''' section.
  
 
=== Lane balance ===
 
=== Lane balance ===
 
:''Main article: [[Balancers#Lane_Balancers|Lane Balancers]]''
 
  
 
Due to how items are placed onto belts by [[inserters]], their lanes can sometimes become unbalanced. In order to
 
Due to how items are placed onto belts by [[inserters]], their lanes can sometimes become unbalanced. In order to
maintain throughput, balancing the lanes may be necessary. The gifs below show a few ways how to do this:
+
maintain throughput, balancing the lanes may be necessary. The gifs below show two ways how to do this. The former only works if only one lane is in use initially. For further explanation of the mechanics, see [[Balancer mechanics#Lane_balancers|lane balancers]].
  
 
[[File:Transport_belts_balance1.gif|top]]&nbsp;&nbsp;&nbsp;[[File:Transport_belts_balance2.gif|top]]
 
[[File:Transport_belts_balance1.gif|top]]&nbsp;&nbsp;&nbsp;[[File:Transport_belts_balance2.gif|top]]
  
=== Belt Throughput ===
+
=== Belt throughput ===
 
+
[[File:Stack inserters fill express belt.gif|frame|230px|right|4 [[stack inserter]]s can compress an express belt at stack size 12 for the left inserters and stack size 8 for the right inserters.]]
Maximizing the throughput is important, since it will keep belts efficient. Therefore some definitions need to
+
Maximizing the throughput means ensuring that as many items as possible are transported. Therefore some definitions need to
 
be introduced:
 
be introduced:
  
 
; Speed  
 
; Speed  
: How fast a belt moves.
+
: How fast a belt moves in tiles per second. This is 1.875, 3.75 and 5.625 for basic, fast and express belts.
 
; Density  
 
; Density  
: How tight are the items put onto the belts.
+
: How tight are the items put onto the belts; each straight belt piece can hold exactly 8 items.
 
; Throughput  
 
; Throughput  
: This is speed * density. It describes how many items pass by in a given time.
+
: This is speed × density. It describes how many items pass by at a given time.
  
 
So, there are three opportunities to enhance the throughput:
 
So, there are three opportunities to enhance the throughput:
  
* More density  
+
; More density  
 
+
:Sometimes items have small gaps in between each other that aren't big enough for other items to fit in. However, mining drills, inserters, and belt sideloading can still force an item into these gaps, temporarily squashing the items on the belt. The squashed gap is extended to normal size once the front of the belt starts to move again.
Sometimes items have little spaces next to each other that aren't big enough for other items to fit
+
; More speed  
in. In this case reordering the items can still increase the density. This can be done by temporarily increasing the
+
:If the belts in the factory are already at maximum density, their speed can still be upgraded with better belts.  Finding the bottleneck is the first thing that needs to be done, usually it can be discovered quite easily. There will be a part of the belt where the items don't move quickly (or at all) or stop at maximum density and suddenly they come to a point where this 'stop and go' effect releases itself, the bottleneck has been found. In most cases, this will be the place where belt optimization is needed.
belt speed on a single tile or by merging 2 lanes with an inserter.
+
; More belts  
 
+
:Adding additional parallel belts can also increase the throughput. Simply place more belts carrying the item that needs throughput.
The gif below shows the problem with a low density belt, and the right shows how it can be rectified. (Notice the red belt)
 
 
 
[[File:Transport_belts_density.gif|top|300px]]
 
 
 
* More speed  
 
 
 
If the belts in the factory are already at maximum density, their speed can still be upgraded with better belts.  Finding the bottleneck is the first thing that needs to be done, usually it can be discovered quite
 
easily. There will be a part of the belt where the items don't move quickly (or at all) or stop at maximum density
 
and suddenly they come to a point where this 'stop and go' effect releases itself, the bottleneck has been found.
 
In most cases, this will be the place where belt optimization is needed.
 
 
 
* More belts  
 
 
 
Adding additional parallel belts can also increase the throughput. Simply place more belts carrying the item that needs throughput, and add [[splitter]]s to balance items between them.
 
 
 
 
 
=== Belt Tricks ===
 
 
 
Moving fast can be essential to defend alien attacks in time. Running on a belt will increase or decrease the movement
 
speed of the [[player]] accordingly to the belts speed. That is why building a belt towards your [[defense]]s can
 
be beneficial.
 
 
 
However, the player is not the only unit that can be moved by transport belts. Additionally, biters and spitters can be
 
moved.  This can be abused to improve your defense. Firstly, biters will have a harder time to reach your walls when
 
placing express transport belt in front of them. Secondly, spitters can be moved closer to your walls. That way more
 
turrets can attack a single spitter at once.
 
 
 
Another useful usage are [[car]]s on transport belts. Cars have an inventory and can be filled by [[inserters]].
 
So, they can be used as moving boxes on belts. This has several advantages: Firstly the throughput of the
 
belt-car-boxes is amazingly high, secondly the inserter stack size bonus does apply here and make inserters more
 
effective.  
 
  
 +
=== Belt tricks ===
  
=== Placement ===
+
Moving fast can be essential to defend alien attacks in time. Running on a belt will increase or decrease the movement speed of the [[player]] accordingly to the belts speed. That is why building a belt towards your defenses can be beneficial.
{| style="float:right; padding-left:10px; padding-right:10px;">
 
| style="padding-right:1em" | [[File:Transport_belts_notplace.gif|300px|top]]
 
| style="padding-right:1em" | [[File:Transport_belts_doplace.gif|300px|top]]
 
| [[File:Transport_belts_replace.gif|300px|top]]
 
|}
 
  
While conveyor belts can be placed in a line by clicking and dragging the mouse, it is often easier to hold the mouse down and move your character. Conveyor belts can be rotated after being placed by hovering over them with an empty hand and pressing {{keybinding|r}}, or by building over them with another conveyor belt. Conveyor belts can also be upgraded in this manner, by placing another belt over top of it.
+
However, the player is not the only unit that can be moved by transport belts. Additionally, biters and spitters can be moved. This can be abused to improve your defense. Firstly, biters will have a harder time to reach your walls when placing express transport belt in front of them. Secondly, spitters can be moved closer to your walls. That way more turrets can attack a single spitter at once.
  
{{clear}}
+
Another useful usage is [[car]]s on transport belts. Cars have an inventory and can be filled by [[inserters]]. So, they can be used as moving boxes on belts. This has several advantages: Firstly the throughput of the belt-car-boxes is amazingly high, secondly the inserter stack size bonus does apply here and makes inserters more effective.
  
 
== Splitters ==
 
== Splitters ==
  
[[Splitters]] are another form of item manipulation. Splitters are a 2x1 tile that split incoming items on belts
+
[[Splitters]] are another form of item manipulation. Splitters are a 2×1 entity that splits incoming items on belts
from one input to two outputs, in a 50/50 ratio. They are used to divide resources between two belts, or balance
+
from up to two input to up to two outputs, in a 1:1 ratio. They are used to divide resources between two belts, or balance
 
multiple belts.
 
multiple belts.
  
== Mechanics of splitters ==
+
=== Mechanics ===
  
 
The behavior of splitters looks simple at first glance. But they are not that simple. Splitters have an astonishing amount of uses.
 
The behavior of splitters looks simple at first glance. But they are not that simple. Splitters have an astonishing amount of uses.
  
* Splitters have two input belts, and two output belts. If the splitter receives items on one belt, it will split the
+
* Splitters have two input belts and two output belts. If the splitter receives items on one belt, it will split the input evenly between its two outputs. If one of the outputs is fully backed-up and the splitter cannot split evenly, it will put all input on its other output.
input evenly between it's two sides.
+
* Splitters can also merge belts, taking two inputs and one output.
 
+
* Splitters preserve the lanes of the items, by moving through the splitter an item on the right lane will not be moved to the left lane, and vice versa.
* If one of the outputs is fully backed-up and the splitter cannot split evenly, it will put all input on it's other
+
* Splitters can prioritize one input and/or one output. Clicking on a splitter opens its GUI where the priorities can be set.
output.
+
* One output of the splitter can be filtered to one item. Items of that type will only go to that output, and not to the other one.
 
 
* Splitters can also take two inputs and one output.  
 
  
The output will be an even mix of both the inputs. This can be
+
The speed of the splitter is the same as its relevant type of belt, so in order to properly join/split belts, the splitter must be the same speed as the incoming belts. Otherwise the splitter will become a bottleneck.
used to efficiently merge two belts together. When it does this, the items will not be shuffled.
 
  
In order to join/split belts, the splitter must be the same speed as the incoming belts, otherwise the splitter will
+
==== Priority ====
become a bottleneck.
+
For both the input and output side of the splitter it is possible to set the priority to either left or right.
  
However, when both belts are at full capacity, the splitter will prefer one side, and use the other to fill gaps. This
+
A splitter where the input priority has been set will first try to consume the specified input side, and will only
behavior is due to the game being unable to fairly reverse-split the belts. Explained by the developers:
+
consume the other input once there is a gap on the prioritized input belt.
  
''"But there are fundamental problems with equal joining. How exactly will you define it?  Once you have an available
+
Similarly a splitter where the output priority has been set will try to redirect all incoming items
item to move to the belt on the left belt, you would have to wait, if some other item on the right belt doesn't
+
to the specified output, and will only output on the other output once the specified output is full.
arrive, as it would be the time for the right belt to be activated.  But how long do you wait? And once you wait you
 
limit the throughput of the splitter."''
 
  
This behavior can be used to prioritize input from certain belts, such as from a storage.
+
==== Filter ====
 +
If a specific item is set in the splitter's filter slot, the slider for the output priority will
 +
be used for the filter instead. All items of the set type will be redirected to that specific output
 +
and all other items are directed to the other output. The input priority can be set independently of the filter.
  
 
=== Balancing ===
 
=== Balancing ===
  
{{Main|Balancers}}
+
{{Main|Balancer mechanics}}
  
 
Balancers are used to evenly distribute items over multiple belts or multiple belt lanes.
 
Balancers are used to evenly distribute items over multiple belts or multiple belt lanes.
  
 +
=== Manipulating belt lanes ===
 +
<gallery mode="slideshow">
 +
File:Swap_belt_lanes.png|Swapping lanes on a belt with a different item per belt lane.
 +
File:Splitter_seperate_belt_lanes.png|Separating lanes with different items on them.
 +
</gallery>
  
== Underground belts ==
+
== [[Circuit network]] ==
  
 +
[[File:transport_belt_circuits.png|thumb|200px|Two belts connected to a [[constant combinator]].]][[Red wire|Red]] or [[green wire]]s can be connected to segments of transport belts to use them as part of a circuit. Belts connected to the circuit network will appear with a yellow cage above them, with a moving red scanner within it. When a belt is connected to a circuit, a GUI can be accessed from the connected belt for settings on how the belt will be used for a circuit; there are two modes of operation that can be used:
  
Underground belts can be used to cross different flows of items without interfering. They move items like a [[Transport belts|normal belt]].
+
'''Enable/disable''' - A circuit condition dictates whether or not the belt will allow items through.<br />
 +
'''Read belt contents''' - If enabled, the contents on the belt will be read.
  
* You can cross any number of entities and all types of ground, like water, swamps, etc. (input and output of course over water)
+
The belt's GUI will also have a "content read mode" setting, which can be set to either '''pulse''' or '''hold'''. '''Pulse''' will read the belt's contents for only one [[Time|tick]], while '''hold''' will read the belt's contents continuously on every tick.
* You can cross other underground stuff (any number of underground belts or underground pipes). They won't be mixed.
 
* For the connection only the endpoints (entry-side and exit-side) are relevant.
 
* The maximum distance underground is 8 [[tile]]s with [[express underground belt]]s (as of 0.15.7).
 
* An underground belt pair with a blocked output stores up to 20 items. (Per lane? Untested!)
 
* If you mine an underground belt, up to 20 items are recovered, the remaining items in the underground are placed into your inventory.
 
* The half of the underground belt tile with a belt can accept input from the side. The other half (with a tunnel entrance) blocks incoming items.
 
  
''This last fact is important, because it can be used to do some tricks.''
+
[[File:transport_belt_circuit_gui.png|thumb|right|Transport belt GUI.|130px]]
  
:[[File:Split-swap.png|thumb|300x400px|You can turn the order of the lanes or split the lanes completely with the underground belts trick]][[File:Split&swap2.PNG|thumb|300x400px|Narrower version with reversed underground belt flow. Used 1 Fast underground belt to prevent connection]]
+
<gallery mode="slideshow">
 +
File:transport_belt_circuit_example1.gif|A small example of a transport belt circuit reading belt contents to trigger two lamps.
 +
File:transport_belt_circuit_example2.gif|[[Fast inserter]]s are activated by the [[arithmetic combinator]]s' setup; when a specific item enters a belt segment that's connected to the circuit network, the inserters place the same item on another belt.
 +
</gallery>
 +
{{clear}}
  
=== Underground Belt as blocker of one side of belt ===
+
== Underground belts ==
  
To build this you need to place one underground belt and then press R to reverse it's direction. This converts the underground belt entrance to an exit (and vice versa).
+
Underground belts can be used to cross different flows of items without interfering. They move items like a [[Transport belts|normal belt]].
  
This trick and similars has several more usage cases. See down.
+
[[File:4-6-8.png|thumb|right|Underground lengths|200px]]
 
+
* Underground belts can cross any number of entities and all types of ground, like water and grass. (as long as the input and output endpoints are on land)
==== Discussion ====
+
* Underground belts can cross other underground entities (any number of underground belts or underground pipes). They won't be mixed.
 
+
* For the connection only the endpoints (entry-side and exit-side) are relevant.
The opinions in the Factorio-forum about this "trick" are mixed. Newer players think this is a bug. The older think, it needs just a graphical rework of the underground belt to make it's function clear.
+
* The underground distance is 4, 6 and 8 [[Map_structure#Tile|tiles]], respectivly, for the three belt types.
 
+
* An underground belt pair that bridges a gap of 4 tiles stores up to 44 items. An express underground belt pair at max length stores up to 72 items.
=== Splitting Belt-Lanes with Underground Belt ===
+
* The half of the underground belt tile with a belt can accept input from the side. The other half (with a tunnel entrance) blocks incoming items.
 
 
With the same trick the underground belts can be used to split the left and right lane of a belt! This trick come up from [http://www.factorioforums.com/forum/viewtopic.php?f=23&t=198&p=938 this forum-thread].
 
 
 
:[[File:Mpstark-ANwfZsj.gif]]
 
On the right is an example how to swap lanes first and then splitting and filling belt with materials of one lane.
 
To understand the picture start at top. The inserters place just copper- and iron-plates on left and right lane of the belt. Then place a splitter and split into two belts. Place an underground belts orthogonal (90 degrees left or right) to each end of the belts. Place the exit-side directly at the next tile. The result is that only one lane of the incoming belt is transported.
 
In the next splitter this procedure is repeated to prove, that the transformation can be reversed.
 
Use splitters to fill two belt-lanes again.
 
 
 
This trick is of course also useful with one underground belt, when you want to transport only one lane and keep the other. You need then of course no splitter.
 
 
 
The big advantage of this construction is, that it doesn't need any energy to run (smart inserters, which sort that, need always energy) and it is much faster than a single smart splitter and cannot "forget" one item. The biggest disadvantage is, that it is a little bit complicated to built (and expensive) and needs some more space (but not much more, when building the same throughput with inserters). But this is definitely a good idea, when you have lots of items on different lanes of a belt and want to have them distincted.
 
 
 
===Example usages===
 
* See [http://www.factorioforums.com/forum/viewtopic.php?f=18&t=3211&p=23636#p23636 this thread] for joining two lanes into one.
 
* more than 20 furnaces on one belt cannot be supplied with only one lane (the other lane for the coal). Instead the inner belt supplies the furnaces with iron ore and on the two outer belts one line each with coal and the other line for the produced iron-plates.
 
* Production of red potion: the inner line of the belt for the produced iron gear wheels, the outer line for the produced red potion.
 
* a very distant and not so big mining site with both iron- and copper-ore fill the items each on one lane of the long belt, that transports it from there to your factory. In the factory this is resplitted.
 
  
=== Swap lanes ===
+
=== Separating belt lanes ===
 +
<gallery mode="slideshow">
 +
File:Block belt lane.png|This is built by placing one underground belt and then using R to reverse its direction. This converts the underground belt entrance to an exit (and vice versa).
 +
File:Transport belts unmerge.gif|This can also be used to split the lanes of a belt onto seperate belts instead of using a splitter filter.</gallery>
  
With curves:
+
=== Braiding ===
:[[File:SplittingLaneSimple.jpg|300x200px]]
+
<gallery mode="slideshow">
 +
File:underground_belt_braiding.gif|Different types of underground belts can be braided together along the same line of tiles, with items staying in their respective belt types.
 +
File:underground_belt_braiding2.gif|The same concept, but with a different belt design.
 +
</gallery>
  
Without curves:
+
Braiding can be particularly useful where more than two input lanes are required while also avoiding the use of a parallel belt/[[long-handed inserter]] combination. For example, this can be useful if there is limited space, such as when using a beacon. With a beacon range of 3 orthogonal tiles, two of which would be occupied by a belt and inserter, it would not be possible to place the parallel belt in the third space and still have a beacon on the same side, as the assembler would now be in the fourth tile and not in range. With the space saved by braiding, this is now possible.
:[[File:LaneSwapperWithoutTurns.jpg|300x200px]]
 
  
 
== See also ==
 
== See also ==
* [[Splitter]]
+
* [[Splitters]]
* [[Transport belt]]
+
* [[Transport belts]]
* [[Underground belt]]
+
* [[Underground belts]]
* [https://www.youtube.com/watch?v=tnj8YhvJE_o A Video about Factorio Belt Mechanics, Tipps & Tricks (Youtube, 5min)]
 
  
 
{{C|Belt transport system}}
 
{{C|Belt transport system}}

Latest revision as of 08:42, 22 June 2021

Transport belt preview.png

The belt transport system is the first system the player will use to transport items from place to place. It, along with trains, and Logistic robots, makes up the systems of item transportation in Factorio.

Belts specifically are used to transport items and run without using energy. Belts can also interact with other moving entities such as players, vehicles and enemies, also allowing for faster or slower movement speed.

Belt tier overview

Animation showing the three types of belt and their speed (from top to bottom: regular belts, fast belts, and express belts).

There are 3 different tiers of belts available for use. The transport belt has a yellow color and is the slowest, as well as the cheapest to craft. The next tier up, the fast transport belt has a red color and is twice as fast as the standard transport belt. The express transport belt is the final tier. It is colored blue and is three times faster than normal belts, or 1.5× faster than red belts.

Transport belts Underground belts Splitters Max. throughput
(Items/second)
Needed research
Transport belt.png
Transport belt
Underground belt.png
Underground belt
Splitter.png
Splitter
15 Logistics (research)1
Fast transport belt.png
Fast transport belt
Fast underground belt.png
Fast underground belt
Fast splitter.png
Fast splitter
30 Logistics 2 (research)
Express transport belt.png
Express transport belt
Express underground belt.png
Express underground belt
Express splitter.png
Express splitter
45 Logistics 3 (research)

(1) Only for the underground belt and splitter. The basic transport belt is available at the start of the game.

Regardless of the belt tier, a fully filled straight transport belt holds 8 items in total. For more information on this, see Transport belts/Physics and Friday Facts #276 - Belt item spacing.

Belt mechanics

Merging and un-merging belts

Belts of all tiers have 2 lanes for items to ride on. This allows for either a double flow of one material, or to transport two different materials on the same belt. Mixed belts can be beneficial for smelting ore, or producing items with many different ingredients such as Utility science pack. The belt can be unmerged using a splitter filter. It is also possible to unmerge a mixed belt by using underground belts since an underground belt will block half of the belt.

Transport belts 2 lanes.gif   Transport belts unmerge.gif

Belts going across a splitter will have items from the splitter moving to one side of the crossing belt.

Splitters moving objects to just one side of a belt.

Commonly, merging and un-merging is done by using a splitter. The trick in the second gif is better described in the underground belt section.

Lane balance

Due to how items are placed onto belts by inserters, their lanes can sometimes become unbalanced. In order to maintain throughput, balancing the lanes may be necessary. The gifs below show two ways how to do this. The former only works if only one lane is in use initially. For further explanation of the mechanics, see lane balancers.

Transport belts balance1.gif   Transport belts balance2.gif

Belt throughput

4 stack inserters can compress an express belt at stack size 12 for the left inserters and stack size 8 for the right inserters.

Maximizing the throughput means ensuring that as many items as possible are transported. Therefore some definitions need to be introduced:

Speed
How fast a belt moves in tiles per second. This is 1.875, 3.75 and 5.625 for basic, fast and express belts.
Density
How tight are the items put onto the belts; each straight belt piece can hold exactly 8 items.
Throughput
This is speed × density. It describes how many items pass by at a given time.

So, there are three opportunities to enhance the throughput:

More density
Sometimes items have small gaps in between each other that aren't big enough for other items to fit in. However, mining drills, inserters, and belt sideloading can still force an item into these gaps, temporarily squashing the items on the belt. The squashed gap is extended to normal size once the front of the belt starts to move again.
More speed
If the belts in the factory are already at maximum density, their speed can still be upgraded with better belts. Finding the bottleneck is the first thing that needs to be done, usually it can be discovered quite easily. There will be a part of the belt where the items don't move quickly (or at all) or stop at maximum density and suddenly they come to a point where this 'stop and go' effect releases itself, the bottleneck has been found. In most cases, this will be the place where belt optimization is needed.
More belts
Adding additional parallel belts can also increase the throughput. Simply place more belts carrying the item that needs throughput.

Belt tricks

Moving fast can be essential to defend alien attacks in time. Running on a belt will increase or decrease the movement speed of the player accordingly to the belts speed. That is why building a belt towards your defenses can be beneficial.

However, the player is not the only unit that can be moved by transport belts. Additionally, biters and spitters can be moved. This can be abused to improve your defense. Firstly, biters will have a harder time to reach your walls when placing express transport belt in front of them. Secondly, spitters can be moved closer to your walls. That way more turrets can attack a single spitter at once.

Another useful usage is cars on transport belts. Cars have an inventory and can be filled by inserters. So, they can be used as moving boxes on belts. This has several advantages: Firstly the throughput of the belt-car-boxes is amazingly high, secondly the inserter stack size bonus does apply here and makes inserters more effective.

Splitters

Splitters are another form of item manipulation. Splitters are a 2×1 entity that splits incoming items on belts from up to two input to up to two outputs, in a 1:1 ratio. They are used to divide resources between two belts, or balance multiple belts.

Mechanics

The behavior of splitters looks simple at first glance. But they are not that simple. Splitters have an astonishing amount of uses.

  • Splitters have two input belts and two output belts. If the splitter receives items on one belt, it will split the input evenly between its two outputs. If one of the outputs is fully backed-up and the splitter cannot split evenly, it will put all input on its other output.
  • Splitters can also merge belts, taking two inputs and one output.
  • Splitters preserve the lanes of the items, by moving through the splitter an item on the right lane will not be moved to the left lane, and vice versa.
  • Splitters can prioritize one input and/or one output. Clicking on a splitter opens its GUI where the priorities can be set.
  • One output of the splitter can be filtered to one item. Items of that type will only go to that output, and not to the other one.

The speed of the splitter is the same as its relevant type of belt, so in order to properly join/split belts, the splitter must be the same speed as the incoming belts. Otherwise the splitter will become a bottleneck.

Priority

For both the input and output side of the splitter it is possible to set the priority to either left or right.

A splitter where the input priority has been set will first try to consume the specified input side, and will only consume the other input once there is a gap on the prioritized input belt.

Similarly a splitter where the output priority has been set will try to redirect all incoming items to the specified output, and will only output on the other output once the specified output is full.

Filter

If a specific item is set in the splitter's filter slot, the slider for the output priority will be used for the filter instead. All items of the set type will be redirected to that specific output and all other items are directed to the other output. The input priority can be set independently of the filter.

Balancing

Main article: Balancer mechanics

Balancers are used to evenly distribute items over multiple belts or multiple belt lanes.

Manipulating belt lanes

Circuit network

Two belts connected to a constant combinator.

Red or green wires can be connected to segments of transport belts to use them as part of a circuit. Belts connected to the circuit network will appear with a yellow cage above them, with a moving red scanner within it. When a belt is connected to a circuit, a GUI can be accessed from the connected belt for settings on how the belt will be used for a circuit; there are two modes of operation that can be used:

Enable/disable - A circuit condition dictates whether or not the belt will allow items through.
Read belt contents - If enabled, the contents on the belt will be read.

The belt's GUI will also have a "content read mode" setting, which can be set to either pulse or hold. Pulse will read the belt's contents for only one tick, while hold will read the belt's contents continuously on every tick.

Transport belt GUI.

Underground belts

Underground belts can be used to cross different flows of items without interfering. They move items like a normal belt.

Underground lengths
  • Underground belts can cross any number of entities and all types of ground, like water and grass. (as long as the input and output endpoints are on land)
  • Underground belts can cross other underground entities (any number of underground belts or underground pipes). They won't be mixed.
  • For the connection only the endpoints (entry-side and exit-side) are relevant.
  • The underground distance is 4, 6 and 8 tiles, respectivly, for the three belt types.
  • An underground belt pair that bridges a gap of 4 tiles stores up to 44 items. An express underground belt pair at max length stores up to 72 items.
  • The half of the underground belt tile with a belt can accept input from the side. The other half (with a tunnel entrance) blocks incoming items.

Separating belt lanes

Braiding

Braiding can be particularly useful where more than two input lanes are required while also avoiding the use of a parallel belt/long-handed inserter combination. For example, this can be useful if there is limited space, such as when using a beacon. With a beacon range of 3 orthogonal tiles, two of which would be occupied by a belt and inserter, it would not be possible to place the parallel belt in the third space and still have a beacon on the same side, as the assembler would now be in the fourth tile and not in range. With the space saved by braiding, this is now possible.

See also