Editing v0.34:Minecart

{{quality|Masterwork|22:56, 17 March 2013 (UTC)}}{{av}}{{Buggy}}
A '''minecart''' is a [[tool]] used mostly for [[hauling]], which was introduced in version 0.34.08. It is made of [[wood]] at a [[carpenter's workshop]], or [[metal]] at a [[metalsmith's forge]] (using the [[Metal crafter|Metalcrafting]] labor.) Minecarts store up to five times as many items as [[wheelbarrow]]s and are quite a bit faster than hauling dwarves, but have the disadvantages of requiring a dedicated track network, a complex route planning phase, and the possibility of dwarves [[fun|blundering into the path of carts filled with lead ore]]. Above-ground tracks are possible, but more difficult due to their additional [[building material|material requirements]].

Just like wheelbarrows, minecarts are considered [[item]]s and are stored in a [[furniture]] [[stockpile]]. Despite their five times greater capacity, they are only one third larger than wheelbarrows and are identical in base [[item value|value]] when made from the same [[material]] (the value may differ due to the [[item quality]]). As items, [[thief|thieves]] or even mischievous animals can steal minecarts, even when moving on a track. If a minecart is moving fast enough, or if it has a rider, thieves will be unable to steal the minecarts.

Although most of the utility of minecarts is in [[fortress mode]], an [[adventure mode|adventurer]] can also ride in a minecart. Adventurers can also pick up and relocate minecarts.

The invention of minecarts revolutionized the [[minecart logic|Science of Dwarfputing]] by enabling smaller, faster logic systems to be built.

== Basic Minecart Usage ==
The minecarts can be used to swiftly transport both dwarfs and large amount of items, but before you have a functional minecart there are several preconditions that need to be met. First of all you need a actual minecart, constructed either in a [[carpenter's workshop]] or [[metalsmith's forge]]. For the minecart to be able to move you also need to carve or construct a track, which could be as simple as a straight line. Finally you need to construct stops on your track from where the minecart will start and stop. 

After you have created the stops and assigned a cart to the track, you must create logic routes connecting several stops and designate starting conditions for each stop. This is done with the {{k|h}}auling key. The most basic conditions are how the carts movement is initiated and in which direction the cart should start moving. Carts can be either be Pushed (a dwarf stand at a stop and gives the cart a single push) or Guided (a dwarf continually pushes the cart forward, guiding it along the track). The [[hauling]] [[labor]] required for pushing and guiding carts is called "Push/Haul Vehicles" and is turned on by default.

To control which items to transport you can add conditions specifying: (1) which kind of items to be loaded, and unloaded, (2) stockpile links to define which stockpile(s) the items should be un/loaded to and from.

===Capacity and weights ===
Minecarts have five times the [[Weight|capacity]] of [[wheelbarrow]]s. 

'''Examples of the capacity of one cart'''
{| class="wikitable"
|-
! Item
! Amount
|-
| [[stone]]
| 5
|- 
| [[wood|log]]
| 10
|-
| [[block]]/[[bar]]
| 83
|-
| [[Kitchen|prepared meals]]
| 500
|-
| [[Trap_component#Spiked_ball|spiked balls]]
| 500
|-
| [[Weapon#Native_weapons|mace]]
| 625
|-
| [[Weapon#Native_weapons|spears]]
| 1250
|-
| [[cloth]]
| 2500
|}

The weight of the loaded minecart does not affect the initial velocity received from pushing or launching from a roller. Though, the load of a minecart do affect whether a [[pressure plate]] triggers or not, based on the pressure plate's setting.

'''Weights of different carts'''
{| class="wikitable"
|-
! Type of cart
! Empty cart
! Fully loaded (items)
|-
| oaken minecart 
| 28Γ
| 378Γ (10 oak logs)
|- 
| platinum minecart
| 856Γ
| 10482Γ (gold bars)
|  
|}

=== Creating tracks ===
The tracks, which the minecarts travels on, can be built in two ways: Engraved/carved or constructed. The way the tracks are built is slightly different between the two, as explained below.

====Simple tracks====

'''Carved'''

A single-tile wide strip of natural stone can be designated to be [[Engraver|carved]] (with {{K|d}} {{k|T}}), which will create a straight two-way track. The creation of corners, crossings, and T-junctions is as simple as designating another strip of track that overlaps an existent or newly-designated track. Engraved tracks are removed by [[smoothing]] the rock they're on, which results in a smooth floor (that can be re-engraved if necessary), or by building a [[floor]] on top and subsequently removing it.

'''Constructed'''

Tracks can also be built as regular [[construction]]s (through {{K|b}} {{K|C}} {{K|T}}). This method is resource-expensive, since each track tile requires one stone, [[bar]], or [[block]] for construction, and time-consuming, since you can't designate strips larger than 10 tiles at a time. Corners, crossings, T-junctions, and ramps also have to be designated individually. However, it is usually the only way to build tracks above ground or on soil (barring the [[Obsidian farming|creation of obsidian]]), and the only way to create one-way tracks. Constructed tracks are designated for removal like any regular construction; be aware that removing track ramps built on top of natural ones will also remove the original ramp, leaving a flat floor.

====Ramps====

'''Carved'''

The carving of natural ramps is a little more confusing: to carve a two-way track on a ramp (natural only, does not work on constructed ramps), you must designate the track '''starting on the ramp and one square beyond''' in the direction you want the track to go. For the side of the ramp square you want to head upward, there '''must''' be either a natural or constructed wall in the square next to it, otherwise the game assumes you are trying to carve it on the same level -- this can result in the track being carved underneath a door or other object. If you have accidentally done this, you can correct it by smoothing the ramp and constructing a single square of wall next to it, then re-carving the ramp correctly. (However, the wall must stay there permanently; removing it will disconnect the track.)

'''Constructed'''

When constructing track ramps, the stated direction should be the same as the connected tracks. For example, a track going up from West to East would require, starting from the West, a Track (EW), a Track/Ramp (EW) and a Wall behind the ramp. Incorrectly placed ramps result in minecarts ignoring the ramp and crashing into the supporting wall. They will not, however, display as unusable as when the supporting wall is missing.

'''Examples of ramps'''

A simple ramp would look like this: 
 z +0   z +1
 ░░░░   ░░░░
 ═▲o    ░▼═
 ░░░░   ░░░░
o : wall

Carving track corners into ramps is rather unintuitive and complicated. Since engraving tracks always requires two tiles to connect in a straight line as input, you have to give two separate designations for a single job: a track bit from the ramp tile to the "below" direction and another one to the wall of the "upward" direction. If you wanted to change direction on a ramp from east to north:

 z +0    z +1  
 ░░░░░   ░░░░░ 
 ░░░░░   ══╗░░ 
  =▲░░   ░░▼░░ 
 ░░░░░   ░░░░░ 

you would need to connect the ramp on z +0 both to the west and to the north by issuing two "carve track" commands, one selecting the ramp and the track tile to the west, and another connecting the ramp tile with the wall to the north. An engraver would then carve a NW track corner into the ramp, allowing carts to pass the corner correctly both going up and down. Such track corners are perfectly serviceable for guided carts, but moving down a route of several of them by pushed or ridden cart is problematic - the ramp-induced acceleration can easily lead to collisions with walls, dropping all contents of the cart and battering the rider.

=== Hauling route ===
The proper setting up of routes is essential for a working rail system. Routes, stops, departure conditions and stockpile links are managed from the {{k|h}}auling menu.

==== Route ====
New routes are created with the {{k|h}}auling key. Existing ones can be removed (without confirmation) with the {{k|x}} key, and also {{k|n}}icknamed. Before operating, the route must have at least one {{k|v}}ehicle assigned to it (this can be done with either the route or a stop selected). Assigning a full minecart to a route may result in a slow hauling job if the contents are heavy.

==== Track stop ====
Track stops are not mandatory; in fact, their main use is in automated rail systems, to stop and hold extremely fast-moving minecarts or to dump contents mid-way without stopping. However, even in basic rail systems it can be useful to set a track stop to dump items: this saves time that dwarves would otherwise spend in removing items from the cart, time that is better spent driving the cart back to where it's needed. Take care not to set track stops at a loading site to dump their contents, or dwarves will never be able to fill the cart.

Track stops are designated by moving the cursor on top of the desired tile and pressing the {{k|s}} key afterwards. They can be removed with and nicknamed with the same hotkeys as routes. Stops can also be reordered with the {{k|p}}romote key. Without a definition, however, a stop is fairly useless: pressing the {{k|Enter}} key with a stop selected in the route menu opens its stop definition screen, from which departure conditions and stockpile links can be set up.

Each new stop get the same default conditions regardless of the track it is placed upon (e.g. guide the cart to the north). For this reason new stops might get marked by yellow exclamation marks ({{DFtext|!|#ff0}}) due to invalid directions. 

Counter-intuitive to their construction method, track stops are considered [[building]]s and must be removed by {{k|q}} {{k|x}}.
* See [[#More_on_Track_stop |More on Track Stops]]

===== Stockpile links =====
By placing the cursor on top of a stockpile and using {{k|s}}, you can create stockpile links for a track stop. Links can also be redefined by selecting them, placing the cursor over a different stockpile, and pressing {{k|p}}.
[[#More_on_Track_stop| See More on Track stop]]

===== Departure condition =====
Departure conditions involve setting conditions in which the minecart will leave on the route. Each condition includes:
# A departure mode (Guide, Ride or Push).
# A departure direction (NSEW).
# A timer, before which the departure condition cannot be met.
# Conditions on the amount of items in the cart.
Departure conditions are created with the {{k|n}} key. A new departure condition will read: "guide north immediately when empty of desired items". This condition can be changed between basic presets with {{k|c}}. "Advanced" mode ({{k|C}}) allows for more precise control over departure conditions: fine tuning the percentage from 0 to 100 in 25% steps ({{k|f}} and {{k|F}}), switching it being either the maximum or the minimum amount of items for the condition to be met ({{k|m}}), and whether the cart accepts all or only a specific set of items ({{k|l}}). Common to both screens are the departure mode ({{k|p}}, Push, Ride or Guide), {{k|d}}irection, and timer ({{k|t}} and {{k|T}}) options.

To have a cart only carry a specific set of items, the stop can be set to only carry "desired" items, opening the selection screen with the {{k|Enter}} key while having said stop condition selected, and toggling as desired, or it can simply be linked to a restricted stockpile and set to depart with any items.

=== Step-by-step tutorial ===

Let's construct a simple minecart route.  This route will move stone blocks from an input stockpile to an output stockpile.  We'll begin by creating the stockpiles:

[[File:minecart-example-1.png|Stockpiles designated.]]

The input stockpile is on the left; the output stockpile is on the right.  We'll be moving blocks from left to right.  Disable bins in both stockpiles, and set the input stockpile to accept only from links.  Then make the stockpile take from the mason's workshop where the blocks are being produced.

Next, carve the track:

[[File:minecart-example-2.png|Track carving designation.]]

Note that the ends of the designation are uniquely shaped; this is automatic, and not anything you need to control.  Now, wait for your engravers to come along and carve the track into the stone.  (Your haulers will probably also fill up the input stockpile while you wait.)

In addition, while we're waiting for that to happen, we'll build an iron minecart in the forge.

[[File:minecart-example-3.png|Track carved.]]

When the track has been carved, it will look like the above (the track will be solid instead of flashing).  Now, order a track stop to be constructed next to the output stockpile:

{|
| [[File:minecart-example-4.png|Track stop designation.]]
| [[File:minecart-example-5.png|Select dumping direction.]]
|}

You must press {{k|d}} three times to select the dumping direction ''before'' placing the track stop.  We want our blocks to be dumped into the output stockpile east of the track stop.  Then wait for a mechanic to come along and build the track stop.

[[File:minecart-example-6.png|Track stop constructed.]]

Now we'll define the actual ''route''.  This is done in the {{k|h}}auling menu.  Press {{k|r}} to begin defining a route.  Next, move the cursor to the input end of the track, and then press {{k|s}} to define the first stop:

{|
| [[File:minecart-example-7.png|Stop 1 designation.]]
| [[File:minecart-example-8.png|Route definition, in progress.]]
|}

Move the cursor again, to the output end of the track, and press {{k|s}} again to define the second stop:

{|
| [[File:minecart-example-9.png|Stop 2 designation.]]
| [[File:minecart-example-10.png|Route definition, two stops.]]
|-
|
| [[File:minecart-example-11.png|Stops are not defined yet.]]
|}

There are several user interface features to note at this point.  The stops have been positioned, but they haven't been ''defined'' yet, so there is a warning {{DFtext|!|#ff0}} symbol by each of them.  In the lower right corner, we see what the {{DFtext|!|#ff0}} means.  Also, note that the second stop is labeled in white, while the other two lines are grey.  The white text is a selection indicator, and can be moved up and down by pressing {{k|+}}/{{k|-}}.

Next we need to define what our stops do.  We want the minecart to be filled with blocks at the first stop, then travel to the second stop where it will dump its cargo, and then return.  Press {{k|-}} to move the selection up to stop 1, and {{k|Enter}} to open it up.  By default, the stop has three conditions:

[[File:minecart-example-12.png|Default stop definition.]]

We don't want any of these, so press {{k|x}} three times to delete them.  This leaves us with a blank stop.  Now we can add the conditions we actually want.  Press {{k|n}} to begin adding the first condition, then {{k|d}} twice to change the direction from north to east.  Then press {{k|c}} to change the condition from empty to full.  This will instruct the minecart to be guided east when full of desired items.

To set the desired items, we create a stockpile link.  Press {{k|s}}, then move the cursor to the input stockpile, then press {{k|p}} to select that stockpile.  Now press {{k|Enter}}; this opens up a selection screen that resembles the stockpile customization screen.  Move down to Blocks, {{k|e}}nable them, then (if you wish) restrict it to stone blocks.

When you've done all that, stop 1 should look like this:

[[File:minecart-example-13.png|Stop 1, defined.]]

Stop 2 is much simpler.  All we need to do is have the minecart return to the input stop.  So, make a condition and change the direction:

[[File:minecart-example-14.png|Stop 2, defined.]]

Finally, we just have to assign our minecart.  Go back to the route definition screen, and press {{k|v}}.  Select the minecart, and press {{k|Enter}}.

Now we've got everything set up:

[[File:minecart-example-15.png|Route, fully defined.]]

The V is red because the minecart hasn't been moved onto the track yet.  Some dwarf will have to haul it from the forge to the first stop, by hand; this will take a while, especially if the forge is far away.

Once the minecart is in place, dwarves should fill it with blocks from the input stockpile, which will in turn be filled with blocks from the workshop where your mason has been toiling dutifully.  When the minecart is full, the blocks will be dumped into the 1x1 stockpile on the right.  Automatic quantum dumping!

=== Troubleshooting ===

Because of the complexity of the system, all but the most careful and experienced minecart users will encounter issues. Most route issues can be diagnosed and fixed from the {{k|h}}auling menu.  

'''Symptom:''' {{DFtext|! Set dir/connect track|6:1}} message appears to the right of one or more stops 

'''Possible Causes:'''
* The departure direction of the stop might be invalid. Edit the stop using {{k|Enter}} and press{{k|d}} until it is pointing in a valid direction.
* The track stop might not be built on top of a track. The track stop must be deconstructed to remedy this issue.
* Your track might not be built correctly. Make sure all connected tracks between destinations are not one-way tracks.
** This can be especially confusing with ramps. To carve a two-way track on a (natural) ramp, you must designate the ramp <b>and one square beyond</b> in the direction you want the track to go.
** Ramps '''must''' have a solid block on the side opposite to the track, or they will neither work nor be marked as "unusable". The solid block can be natural or constructed.
* The desired/kept items might not be configured correctly.

'''Symptom:''' The status '''0% <span style="color:#00dd00;">V</span>''' always appears to the right of one stop.  

'''Possible Causes:''' 
* The stop may not be set to take from a stockpile. Edit the Stop using {{k|Enter}} and make sure you see a message like "Take from Stockpile #1".
* The take conditions must correspond with the contents of the stockpile.
* The track stop may be set to dump. A track stop set to dump cannot be filled. You must either set the stop to a time-based departure or deconstruct the track stop and rebuild it without dumping.
* Make sure the minecart itself has not been designated to be dumped (such as when using mass-dump).

'''Symptom:''' A dwarf picks up the minecart and carries it to its destination.
* See [[#Quirks|Quirks]]

=== Danger ===
Minecarts are not without [[Fun|danger]]. Although designating a track automatically sets the [[traffic]] designation to low, dwarves ''may'' still walk on them, and [[creature]]s ignore traffic designations altogether. If an unlucky dwarf or creature fails to [[dodger|dodge]] a minecart, they can be injured. Most of this danger can be avoided by setting the minecart {{k|h}}auling commands to guide instead of push or ride, as dwarves guiding minecarts will ignore traffic restrictions, by [[pasture|pasturing]] domestic animals, and preventing the access of other creatures to the tracks. Note that removing the track doesn't reset that tile back to normal traffic priority, so you may wish to manually clean up traffic designation afterward. Also note that bridges that are used as tracks don't have their traffic priority changed automatically (since they're just normal bridges), which could cause dwarves to pathfind normally through dangerous minecart entrances in your fort's walls if you're not careful.

Danger does not always involve living victims: careless route designation can also result in minecarts careening off tracks or colliding with each other. If this occurs, the [[item]]s may be scattered; this can cause even more hauling jobs than the minecart aimed to eliminate. Even <s>better</s> worse, scattered items, especially [[weapon]]s, can injure passing [[dwarf|dwarves]] or other [[creature]]s; in the words of Toady One the Great, "Accidental grapeshotting of the dining room should be possible now."

Of course, the danger of using minecarts means they can also be [[Trap_design#Minecart_launcher|used as weapons]] by imaginative players.

== Advanced usage and automation ==
Minecart-specific effects are implemented via track stops, rollers and [[pressure plate]]s with "track" condition set. Since all three are considered [[building]]s, they can't be built on the same square (however convenient track stop + pressure plate would be) nor a simple ramp, and are removed by {{k|q}} {{k|x}}. 

=== More on Track stop === 
Track stops are constructions that allow further automation of minecart systems via adjustable features such as braking by friction and automatic dumping of contents. They can be built from logs, bars and blocks through {{K|b}} {{K|C}} {{K|S}}; friction amount, dumping toggle and dumping direction must be set '''before''' construction, and these settings can be neither changed nor seen thereafter; however, track stops can be linked to [[pressure plate]]s or [[lever]]s to toggle friction and dumping On or Off (trigger state is inverted: switch On = track stop Off). 

If a [[stockpile]] is placed on the tile that a track stop is set to dump to, it can act as a [[Exploit#Quantum_stockpiles|quantum stockpile]] and any items dumped from a minecart that match the storage settings of the stockpile will remain there and accumulate.  Normally trackstops are built on top of existing track to operate on moving minecarts, but they can also be used without tracks to create [[Exploit#The_Minecart_Stop|automatic quantum stockpiles]] (see also [[#Example|route example]]).  It is not always desirable to collect ALL of certain items into one quantum stockpile, such as when distributing a material to multiple separate industries. You can link your quantum stockpile to various other stockpiles, ensuring that your dwarves will keep them supplied as necessary. Because quantum stockpiles never fill up like regular stockpiles, it may be a good idea to add a switch to turn them off.  

Items dumped from a minecart at a track stop (or dumped by any other means) into open space fall through z-levels until they land on a solid surface.  Items falling onto a designated [[stockpile]] will automatically be considered part of that stockpile, even if the stockpile is set to disallow those items (they will, however, be automatically moved to a more appropriate stockpile, if available).  Items falling on top of a minecart will '''not''' fall "inside" the minecart.  Use with caution; dwarves have fragile skulls.{{bug|5945}}

=== Automated propulsion ===
==== Roller ====
{{Machine component|name=Roller|key=r
|construction=
* 1 or more [[Mechanism]]s
* 1 [[Rope]]
|construction_job=
* [[Mechanic|Mechanics]]
|power=Uses 2 power per tile (independent of speed).
}}

A '''roller''' is a [[power]]ed [[machine component]] for the automated propulsion of minecarts. They are built over the top of existing tracks with {{K|b}} {{K|M}} {{K|r}}, requiring a [[mechanic]], one or more [[mechanism]]s and a [[rope]]. Rollers are very useful to maintain a cart's momentum along long routes, to get them to climb Z-levels without dwarfpower involved, and to get them to reach speeds unattainable by guiding dwarves. These devices are variable-length, variable-direction and variable-speed, all traits that can be set at construction time; a roller uses two units of power per tile it is long. 

Rollers do not provide acceleration but rather set the cart's velocity to a new value: if a cart moves across an active roller in the direction the roller works and moves slower than the roller's specified speed, the cart will be set to the roller's speed. Carts going faster than the roller are unaffected. A cart going against a roller's movement direction will be sent back the way it came (once again at the roller's speed), unless it was moving extremely fast, well over derailing speed. A cart crossing over a roller perpendicular to its current movement direction will gain the roller's amount of speed in the perpendicular direction without directly changing its forward motion. Without an adjacent wall to constrict its movement, this will typically send a cart off the rails on a diagonal path, completely unable to follow any tracks until it collides with a wall or is otherwise brought to rest.

Rollers may be placed directly on ramps to help pull carts up Z levels. Currently rollers can only be placed on up or down ramps or open spaces if this results in being connected to existing powered components (gears, axles, or pumps).  For that matter, rollers themselves transfer power along their sides but not from their front or back (the edges on the track) - the opposite of how horizontal [[axle]]s work. Care must be taken in [[glacier]]s and other extremely cold [[biome]]s, since rollers can be rendered inoperable when exposed to freezing [[temperature]]s. Rollers can be constructed over trackless floor or without any floor at all (supported by other machinery) but will not affect carts in either case.

Because of their one-way nature, rollers are unsuitable for most two-way minecart tracks. However, a minecart set to be ''guided'' is not affected by rollers at all &mdash; this allows a one-way track to be used in both directions. In addition, rollers do not affect minecarts when disengaged: switching mechanisms (such as a [[pressure plate]] attached to powering [[gear assembly]]) can be used to create complex paths.

Rollers cannot be powered from above.

==== Impulse ramps ====
Carts can be given momentum without rollers or changing z-level through a phenomenon called "impulse ramps". If a cart derails onto an upward ramp, the ramp accelerates the cart as though it was dropping a z-level, even if the cart doesn't actually change z-level at all.

Example of straight impulse acceleration:

{{diagram|spaces=yes|\
 ▒▒▒▒▒▒▒▒▒▒
═╚╚╚╚╚╚╚╚╚╚═
═ : Normal track 
╔,╚,╗,╝ : N/E Track/Ramp
}}

If a cart enters from the left, it will speed up on every track/ramp and exit to the right going very very fast. 

The other crazy thing about impulse ramps is that they produce slightly more acceleration than it takes to move a cart up one ramp. So you can just make an upward spiral alternating impulse ramps and regular upward ramps. It takes no power, is quick and cheap to build, requiring only channeling and track carving, and the cart goes up fast, but not so fast that it launches its contents.

Example of an impulse elevator:

{{diagram|spaces=yes|\
 z +0    z +1    z +2    z +3
 ░░░░░   ░░░░░   ░░░░░   ░░░░░
 ░╔░░░   ░▼╚╗░   ░░▼▼░   ░░░░░
 ░╝░░░   ░▼░░░   ░░░╔░   ░░░▼░
 ░▼▼░░   ░░░░░   ░░░╝░   ░╚╗▼░
 ░░░░░   ░░░░░   ░░░░░   ░░░░░

░ : Wall
╔,╚,╗,╝ : Track/Ramp
▼ : Down Ramp (empty space)
}}

=== Controlling traffic ===

==== Switching ====
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As constructions or tile features, [[door]]s and other furniture can be built on tracks. A [[door]] or [[floodgate]] can be turned on or off by a [[lever]], effectively controlling the flow of automated minecarts. This may be <s>dangerous</s> [[fun]], however. <!-- How, exactly? -->

[[Bridge]]s can also act as tracks, but only if they're lowered or not retracted. This property can enable levers to turn tracks on and off. However, care should be taken to ensure that such bridges are never operated while a cart is on top of them, as the cart will be flung off the track. It's worth noting that it's often faster, and cheaper, to construct large bridges than long sections of constructed track.

A rudimentary track switch can be constructed by building a T-junction as illustrated below.

      B╥                  B╥
       ║                   ║
       ║         ->        ║
       ║                   ║
 A╞════╚════╡C       A╞════R════╡C

The 'R' is roller pushing from  East to West.
If the cart is pushed East from the stop at 'A' while the roller is activated, it will arrive at 'B'. If the roller is not running, it will arrive at 'C'.

This switch has a disadvantage - it requires power.  An alternative non-powered solution uses controlled derailment, or a connecting bridge.

      B╥
       ║
       ║
 A╞════╝D ════╡C

Here the track between A and C is not continuous. The only continuous track is A->B, with a corner (not a T section). Fast moving carts will tend to derail at D and rejoin the track to C. Placing a door at D will prevent the derailment, so the cart continues to B. The door is operated by mechanisms elsewhere (typically, a lever, but some fun can be had with pressure plates).

If carts are moving too slowly to reliably derail at the corner, a retractable bridge may be used as a connector between A and C.  
      B╥
       ║
       ║
 A╞════bbb════╡C
The bridge must overlap the corner so that it acts as if a T junction track when extended. When retracted, the corner reappears, so the slower carts will continue to B.

==== Controlling Speed ====
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Minecarts can reach extremely high speeds, especially when descending multiple Z-levels. A minecart will derail at a track corner if its speed exceeds 0.5 m/s (here m/s really means tiles per step), '''unless''' the route in the direction of travel is blocked:

Will derail at > 0.5 m/s:

 in  ═╗-> 
     out

Will not derail at > 0.5 m/s:

 in  ═╗O
      |
      v
     out

O is wall.

This behavior can be used to build a "speed limiter", that will ensure that when a minecart exits it is traveling below derail speed:

      OOOO
 in  ═╔═╗O
 out ═╬═╝O
     O╚S╝O
     OOOOO

O is wall, S is a Track Stop set to High Friction or lower. If the minecart is traveling below derailment speed it will not be affected.

=== Loading liquids ===
[[Water]] and [[magma]] can also be loaded into minecarts by submerging them to a depth of at least 6/7, and dumped by a constructed track stop. Loading fluids onto minecarts can be difficult because their weight can slow the minecart down greatly. Curiously, filling a minecart with magma does not injure a dwarf ''riding'' it. A minecart will hold enough magma to increase the depth of a single tile by 2. This amount is listed as 833 units, which weigh 999Γ. An iron or steel cart filled with magma weighs 1313Γ. An adamantine one weighs 1007Γ.

== Quirks ==
This little quirk concerns dwarf managed minecarts and may or may not apply to automatic minecarts. If a track which was previously open becomes blocked (ex. flipping a switch connected to a floodgate you've built on the track to raise it) and the conditions for departure are met, instead of refusing to ride/guide the minecart or ride/guide it until it reaches the obstacle, the dwarf will pick up the minecart off the tracks and haul it to its scheduled destination on foot. If the distance is long enough and the weight of the cart heavy enough (due to being filled with heavy items such as stones), the dwarf may drop the cart because of fatigue/hunger/thirst before reaching the destination. This will cancel that vehicle setting job and make another dwarf come by and attempt to haul the cart to the nearest appropriate stockpile where another dwarf will pick up the cart and attempt to haul it to its initial stop. If the stockpile is far enough from initial stop, this second dwarf who is attempting to place the minecart on its tracks may also drop the minecart out of fatigue/hunger/thirst creating a loop that will go on until a dwarf with enough endurance manages to place the minecart where it belongs.

In fact, it seems dwarves are more than happy to attempt to carry a minecart from one stop to another even if just waiting until the track is open again would be the more sane option.

Dwarves will also carry a minecart to its next stop if the direction specified is incorrect (or invalid). This can often occur when using the default departure settings and forgetting to set the direction of each condition.

== Physics ==
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Minecart physics depend greatly on the departure mode set in the route stop conditions.

When set to "Push" or "Ride", minecarts will move according to the regular laws of momentum, gaining speed when going downhill, losing it slowly due to friction when on a flat plane, and more quickly when going uphill. In these modes, minecarts will move along the track in a straight line until they either run off the tracks or encounter a turn. A minecart will continue straight at a T junction if possible but if it is not possible the track is treated as a dead end and may jump track. The cart's behavior also depends on the weight of its contents (including fluids and dwarves): heavily loaded carts are harder to accelerate and to stop, and gain more momentum when going downhill. In either case, dwarves can not push nor ride an unpowered cart up a ramp, bouncing back the direction it came. At best, this is a waste of time; at worst, it will give your cart-pushing dwarf a [[fun|fun surprise]]. To solve this, the player can either use Rollers (see below) or set the cart to be Guided.

The difference between "Push" and "Ride" is whether the dwarf will go along with the cart or not. When set to "Push", the dwarf will give the cart an initial push, not enough to go up a ramp, but enough to go some way along flat track, and the dwarf will remain at the first stop, ready for a new job. When set to "Ride", the dwarf will give the cart the same initial push and then hop aboard the cart riding with it to the next stop.

When set to "Guide", minecarts seem to ignore all laws of physics. They:
*Ignore the weight of any and all items inside. Therefore:
**Move at the speed of the dwarf that is guiding them. It is thus recommended to pick the most [[attribute#Agility|agile]] of your dwarves for cart-guiding tasks.
*Ignore working rollers.
*Will ''not'' collide with other guided carts even when a full frontal collision would be expected.
*Will go up ramps like nobody's business.
This is therefore the recommended method of transport for simple non-powered rail systems, despite it diverting a dwarf from other, potentially more important tasks.

Some samples with behavior:

  A <-> B     A <-> C               A <-> B
    B╥          B╥                     B╥ 
     ║           ║                      ║ 
 A╞══╝       A╞══╩══╡C              A╞══╬╗
             You can only go A->B       ╚╝
   Works      when the cart           Works     
              is in Guide mode.       

In the second example above, if you attempt to "Push" from B to A or C, [[Fun|''the cart will go careening off of the tracks'']].

=== Skipping ===
If a minecart is moving fast enough, it can skip over [[water]] or [[magma]], making splashes of [[mist]] (or [[magma mist]]) as it attempts to move on them horizontally. This horizontal movement is independent of the minecart and its content's [[weight]].

=== Track Jumping ===
If a minecart encounters the end of the track or a T junction with no "exit" in its movement direction, it will simply leave the track and continue on its course in a straight line until it encounters an obstacle, slows to a stop, or encounters another (properly aligned) Track even if the tile at which it joins the new track instantly sends it around a corner.

=== Falling ===
When falling, a minecart appears to cause no damage upon collision, possibly to allow cart "stacking" across Z-levels. [http://www.bay12games.com/dwarves/#2012-04-06] A dwarf riding in a minecart that is dropped multiple z-levels suffers normal fall damage. Minecarts can fall through up/down stairs.

=== Stacking ===
If a minecart lands on top of another minecart, they may form a stack, with the upper cart on the z-level above the lower. Subsequent carts do not form a stack, but rather quantum stockpile in the same space. This behaviour is useful for [[megaprojects]] and [[trap design]] with minecarts as the weaponry.

These minecarts on the upper level generally need to be struck with another minecart to move out, or have their support removed. The latter option can be somewhat dangerous, however.

=== Numbers behind the scene ===

According to [http://www.bay12forums.com/smf/index.php?topic=112831.msg3536975#msg3536975 this post]:

The minecart has a variable for speed. Speed is measured in tiles/100000 ticks, so a speed of one hundred thousand means one tile per tick. The maximum speed is 270,000. You can hit it exactly by going down enough ramps.

Every tick the cart accumulates distance units, as well as slows down depending on current title (speed is reduced by "friction" of the tile). Once cart accumulates 100000 distance units, it moves to the next tile (or several tiles in case of great speed). Since most deceleration and acceleration is applied per step, with the notable exception of corners, a cart going at twice the speed of another one can cover about four times the distance in a straight line, but only twice the distance along a winding track with very many corners.

When cart is pushed, it will start in the middle of the next tile (so it takes only half of 100.000 to get past it), with the speed of 20000-10 = 19990.

Friction of tiles:
{| class="wikitable"
|-
! Tile
! Friction
! Comment
|-
| Tracks
| 10
|-
| Ground/Floor
| 200
|-
| Unusable ramp
| 10
|-
| Upwards ramp
| 4910 (4900+10)
|-
| Downwards ramp
| -4890 (4900-10)
|-
| Corner track 
| 10
| Speed reduced by 1000 upon leaving the corner tile
|-
| Track stop (highest)
| 50000
|-
| Track stop (high)
| 10000
|-
| Track stop (medium)
| 500
|-
| Track stop (low)
| 50
|-
| Track stop (lowest)
| 10
|-
| Water
| Additional (WaterLevel - 1) * 100
| [[#Skipping|See Skipping]]
|-
| Magma
| Additional (WaterLevel - 1) * 500
| [[#Skipping|See Skipping]]
|-
| Empty space
| 0
|}

== Adventure mode ==
In addition to being used for hauling, minecarts can also be ridden in [[adventure mode]]. (Adapted from [http://www.bay12forums.com/smf/index.php?topic=122903.0 this forum thread])

# If the minecart is in your inventory, drop it. If it is already on the ground, proceed to step 2.
# Press {{k|u}} when you are 1 tile away from the minecart (or standing on the same tile as the minecart).
# You will be presented with the following options:
[[File:minecart adventure mode menu.png|left]]
{{clear}}
* If you {{DFtext|Push}} the minecart, it will move a few tiles in the direction you chose. Physics comes into play here, so it will gain/lose speed depending on the usual factors. 
* If you {{DFtext|Ride}} the minecart, you will hop into the minecart, even if you were a tile away, and it will move in the chosen direction with you in it. It will gain/lose speed depending on the usual factors. Whilst the minecart is in motion, you should press {{k|.}} to skip your turn; if you attempt to move whilst the minecart is still in motion, the laws of physics come into play, and you will take [[wound|damage]]. Alternatively, you can push the minecart whilst it's still in motion (although it's unclear how one can bend [[physics]] so as to push a moving minecart whilst inside the minecart). If you push it in the same direction you are already travelling in, you will greatly increase the minecart's velocity. You can also push it in different directions, and this will cause it to gradually change direction-the amount of pushes this requires depends on the minecart's velocity. Once the minecart has stopped moving, you may move out of it safely, or you may want to give it another push. Note that if you push a minecart right after having ridden it (still on the same tile as the minecart), it will act as though you chose to ''ride'' it.

If you want to test this out without creating an adventurer, the [[object testing arena]] allows you to spawn minecarts ({{k|k}}-{{k|c}}-{{k|n}})

== Bugs ==
*A dwarf will drop its [[child|baby]], if it has one, when boarding a minecart set to be ridden.
*Tracks block wagon access to trade depots.{{bug|6040}}
** This can be avoided by using [[bridge]]s, which also function as tracks (but do not block wagons).
*Dwarves cannot guide a minecart through an unlocked door unless another dwarf opens the door.{{bug|6056}}
*The game will repeatedly crash after a while if a minecart assigned to a route gets [[Steals items|stolen]] or [[trade|traded away]].{{bug|6242}}


{{Category|Fortress mode}}
{{Category|Interface}}

[[ru:Minecart]]