Tutorials/Minecarts

This tutorial covers basic minecart stations and systems and is designed for those without significant redstone knowledge and only minor experience with minecarts and rails. This tutorial doesn't touch on furnace or storage minecart. Images below do not always show a space saving design, but rather one that makes all components immediately visible.

Minecarts
The following are the most important properties of minecarts.
 * Minecarts move at 8 m/s at top speed.
 * Minecarts move further with an entity (mob or player) in them than empty.
 * Powered rails, slopes, and pushing provide momentum.
 * Minecarts will slow down and stop if they aren't properly boosted.

Rails
Rail: Allows carts to move over the block. These are the only type of rail that can create a curve in the track. A track can either curve or go up a slope, not both at the same time.

Detector Rail: Whenever a cart moves over this, the rail will create a redstone signal. Otherwise, it functions like a regular straight track.

Powered Rail: When powered, it increases the speed of a moving minecart up to a max of 8 m/s. If a minecart is placed on a powered rail, the powered rail will not add momentum since there is no preferred direction. Since 1.3 a minecart can be given a slight nudge from the rider. When accompanied by a solid block on one end (like the launcher below), a minecart is given the preference to move away from the block. When unpowered, this rail will stop a moving minecart. See "Powered rails" below.

Activator Rail: When powered, TNT Minecarts going over it will be set off, while a minecart with hopper will be deactivated. Players in minecarts on top of this rail will fall out of the cart (as of snapshot 14w05a).

Effects


Powered rails have two possible states: on or off.

A rail that is "off" slows any passing minecart by applying a frictional force. The force is generally strong enough to bring a moving minecart to a complete stop, or to hold a minecart in place on a slope. However, after going down a slope of 80 or more rail blocks, one non-powered powered rail cannot stop minecarts.

A rail in the "on" state will accelerate a minecart if any of the following is true:


 * 1) The minecart is already moving, in which case the cart is accelerated in the direction of motion.
 * 2) The minecart is stationary, but one end of the powered rail is up against a solid block. In this case, the cart is accelerated in the direction that is not blocked.
 * 3) The minecart is stationary, but the powered rail is on a slope. The instant the powered rail is activated, the brake is released and the cart will start moving down due to gravity. As the cart is now moving, rule (1) applies and the cart is accelerated in that direction.

The second and third cases can both be used to create simple stone button-activated launchpads. When the powered rail is off, carts are held in place, providing a safe way to load and unload carts without them derailing.

Powering
Power can be transmitted to the rail from any of the six adjacent positions (above, below, or any side) in the same way redstone is powered.

Powered rails will propagate power to each other if they are adjacent and part of the same track, for up to 9 blocks from the power source (1 being powered directly which is propagated to 8 adjacent rails). They will also receive power from any adjacent detector rails (when a cart passes over it), even if they are not part of the same track (which follows from the rules above). Because the detector rail powers attached rails, it could be used to activate power rails only when necessary:


 * For one-way travel, place a detector rail before the powered rail
 * For two-way travel, place a detector rail on both sides of the powered rail

In practice it is far more efficient to have powered rails constantly active using other means:


 * Place a redstone torch either next to the powered rail or two blocks underneath it or use powered redstone wiring to achieve the same effect
 * Place an activated lever on the bottom side of the block the powered rail is on (cheapest, only requires a stick and a cobblestone to make)
 * Place the powered rail on a block of redstone

Momentum
The speed of a cart which is boosted using Powered Rails is calculated to be at the maximum of 8 m/s, however the cart maintains an internal "momentum" value that keeps the cart at the maximum speed of 8 m/s until the excess momentum is depleted.

A single powered rail on flat ground against a stop block gives an occupied cart enough momentum to travel 80 rail tiles on a flat surface, or 8 tiles for an unoccupied cart (in Beta 1.5, this was 64 blocks and 8 blocks respectively). Tests show that putting several powered rails in a row has observable diminishing returns with each additional powered rail on how much farther a cart will travel. This implies that the momentum gained is smaller if the cart's speed is faster and vice versa.

Tests show that climbing slopes impact momentum severely, thus the cart speed plummets fast. However, if there is enough surplus momentum, carts will travel up slopes with ease. Conversely, carts traveling down slopes gain momentum. Downward sloped powered rails will add both the momentum from the rails and the momentum from going downhill to your cart.

Climbing slopes


Launching from rest via four powered rails, an occupied cart has enough momentum to climb a 1/1 slope 10 blocks high without further boosting and then travel horizontally at a very slow speed for at least a dozen blocks before coming to a stop. Such a cart does not have enough momentum to climb an 11 block high slope. An empty cart in a similar setup will only climb 5 blocks and then travel a few blocks horizontally.

When minecarts travel upslope without having sufficient stored momentum, a powered rail is needed 1 every 4 blocks to sustain movement all the way to the top of the slope, Alternatively, 2 every 8 blocks are somewhat easier to supply power to. However note this is a worst-case scenario where there is no momentum to start with.

If working with empty carts (for instance, a storage cart transport system), 1 powered every 2 blocks is necessary to sustain movement. To minimize powering requirements, 2 powered followed by 2 unpowered can also be used (analogous to loaded player-carrying carts).

When traveling up a slope at full speed (8 m/s) one powered rail will maintain full speed for two blocks high, meaning that alternating between powered and unpowered rails will maintain full speed up a slope. Consecutive powered rails on a slope will add more momentum, so eight powered rails can be followed by 8 normal rails, and full speed will be maintained while traveling up the slope. Less momentum is gained by each consecutive rail as the strip gets longer.

Optimal Use
A test was conducted by building straight tracks 2000 blocks long on level ground with different intervals of powered rails. The time to travel the full 2 km length on an occupied minecart was recorded with each interval. The following table lists the results:

3 powered rails in a row on flat terrain is sufficient to boost a minecart from rest to the maximum speed of 8 m/s.

Thereafter, the optimal spacing of powered rails on a level track is to use 1 every 38 blocks (that is, a repeating pattern of 1 powered rail followed by 37 normal rails, then another powered rail, and so on) which maintains a constant minecart speed of 7.97 m/s. If gold is in short supply, it is possible to use powered rails with more space between them at the cost of reduced overall speed. If you definitely must have the full 8 m/s you should place a powered rail on a level track 1 every 34 blocks.

However, the optimal spacing of torches is 1 every 13 blocks in order to keep the entire track lit at light level 8 and above. So for aesthetic purposes, it might also be desirable to space out powered rails every 39 blocks with 3.1% speed losses, or to space them out at 1 every 36 blocks with torches 1 every 12 blocks for the same speed loss as 1 every 38 blocks.

An optimal use requires the synchronization of minecart movement and powered rail placement; moving a powered rail a single block forward or back along a track can make a significant difference. This is because the momentum of a minecart is increased per tick (=1/20 of a second) the cart spends on a powered rail (by 0.9 m/s for occupied carts). When a cart travels at the maximum 8 m/s on a straight track, it alternately spends either 2 or 3 ticks on each block. For an optimal placement, the powered rail must be put where the cart spends 3 ticks, otherwise one third of the boost is wasted.

A diagonal track is a track that consists of the pattern 'left corner' attached to a 'right corner' attached to a 'left corner' ... and so on. When minecarts travel on a diagonal track, the camera is held steady in the diagonal direction and the minecart visually travels diagonally along the track as well. The speed limit of minecarts is actually 8 m/s per cardinal axis, thus when traveling on 2D tracks, the cart will travel 8 m/s in both cardinal directions of travel to result in a net vector of about 11.3 m/s or the principal square root of 128. With a 3D track you travel as fast as 13.85 m/s or the square root of 192.

Because of this difference, there is also a difference between the optimal spacing of powered rails when used on a 2D track when compared to straight travel on flat terrain. This is currently undetermined to high accuracy but is roughly 1 every 52 blocks.

There is also a difference in unmanned or storage mine carts so it is advisable to use a shorter interval if these carts will be used on the track.

It seems as if the optimal Powered Rail placing interval to make storage mine carts move is 4 (1 Powered Rail every 4th block). Compared to shorter intervals the reduction in speed is minimal. The maximal possible interval seems to be 9 as the minecart will not reliably reach its destination when using higher intervals.

Usage of detector rails
A Detector Rail will power 4 adjacent blocks and 2 blocks below it when a minecart, occupied or empty, is on it. This makes it possible to activate powered rails inline without redstone torches or wiring.

A detector can be used to activate adjacent powered rails. However, if the detector is used to activate more than two or three (depending on approach speed) powered rails, the rails will deactivate before the minecart reaches them, bringing the cart to an immediate stop.

One-way powered rail lines can be created by placing a detector rail before a powered rail. This way, occupied carts will only be boosted if they are traveling the proper direction. Carts going the "wrong" way will be brought to a stop because the powered rail is inactive.

Although inefficient, A two-way rail line can be created by placing detector rails on either side of the powered rail.

Alternately, placing powered and detector rails on a 1×1 slope will not propel a cart more than 3 blocks upward if there is not enough initial momentum. The cart will lose too much speed on the incline, meaning it can't make it from the detector rail to the powered rail before the powered rail returns to the "off" state. If the cart is in a train of two or more carts, the last car in the train will become stuck instead.

A detector rail could also be used to activate an event based on a cart's location. For example, a fail-safe can be created to release a stopped cart in order to prevent a collision with an arriving cart. The arriving cart passes over a detector rail, activating a powered rail that boosts the resting cart away.

Additional properties


Curved power rails only exist in the case where the final direction is towards the east (with the powered rail appearing in the north-south orientation), or in a T-junction where one path faces east along a north/south track. It is possible to make a one-way curved railway using power rails, but not a bi-directional one.

When placing rails, regular rails prefer to curve towards the powered rail. In cases such as these, the south-west rule applies.

A cart traveling on a powered rail that collides with an object (wall, single block, player, other cart) will reverse direction. It will not reverse direction if it collides with a translucent block, such as Stone Slabs or Glass. If a track including powered rails is bordered by blocks acting as "buffers", the cart will indefinitely continue back and forth along the track. Having carts interact with each other on a short track designed this way can be used to chain multiple carts together as a "train". Once aligned, they will all move together at relatively the same speed.

How far the charge passes down adjacent rails is independent of the length of redstone wire. Even if the rails are connected to a redstone torch by 15 blocks of redstone dust, the 8 adjacent rails will still be powered normally despite the fact that they should be out of range for the torch.

Stop points
It is possible to make points in your track where a cart is stopped and then jumpstarted again by player input. This can be useful for creating checkpoints to certain sites of interest in your world. This can be done by using two powered track pieces on a one block incline, by having the first powered track piece going down, with the second powered track piece at the bottom and a button placed alongside the second powered track piece, so that the button is directly above the track. You can see an animated example of this stop point if you click on the image to the right.
 * Stop Point.GIF

When the cart comes to this point it will stop On the incline, allowing the cart to use gravity to start the boost when the button is pushed. Players can then either stay in the cart and carry on to the next stop, or leave the cart at the station for themselves/other players to use later.

A "two-way" stop can be made by combining two of the normal stops with a detector rail in between. This will pause a minecart travelling in either direction and allow them to be restarted by pressing a button.

Starting boost
To create a simple initial boost device using 2 powered rails, dig a hole 1 block deep and 2 blocks long. Place the powered rails inside the trench, connect one end to the track that you wish the mine cart to exit. Finally place the mine cart on the powered rail. Once power is applied to the rail the minecart will be boosted out.

Launcher
Launchers, stations or exits all refer to a point in the system where a rider can safely enter or exit a minecart. They generally use a button to launch the cart.

This first design uses a button, a few powered rails, a bit of redstone wire, and a redstone torch. The button powers the powered rail which launches the cart away from the solid block behind it. In this style of launcher, it is important for an incoming minecart to make it all the way up to the back block so it can easily be launched again.

This second design is essentially the same as the first. A dispenser replaces the solid block behind the last powered rail. The dispenser will launch the minecart just like the solid block, but creates a convenient place to store extra minecarts. To activate, use the button behind the dispenser and a minecart will pop onto the rail and be ready for use.

See also: Tutorials/Minecart start booster

Rider Detection
Players will tend to want to detect whether a cart has a player in it or not as empty carts will clog a rail system. This is referred to as rider detection.

A trip wire based design is quick to set up and will reliably detect a player. However, it won't detect some non-player mobs, specifically 'short' mobs (wolves, spiders, pigs, etc.).

To build, a trip wire is attached to hooks one block above the track. Two blocks further is a junction which is set by default to turn empty carts back to the station. An empty minecart will not trigger the trip wire and be sent back, while an occupied minecart will send a short pulse to the junction and continue along the rest of the track. Depending on orientation, the signal may need to be inverted with a redstone torch. Although the torch will add delay, it is minor and shouldn't affect the results. This design assumes the minecart is moving at top speed. If your minecart is moving slower than that, you can either add delay to the wire using repeaters or increase the speed of the minecart with a booster just before the trip wire.

Another method to check for a rider is to take advantage of the change in speed of the cart, as an empty cart slows down more quickly. In this design, a minecart will create a pulse when it passes the detector rail. If the minecart is empty, it will get to the turn just as the signal does and be sent back. If the minecart has a rider, it will get to the turn before the signal and be able to continue on. This design requires the track to be set by default to let the cart through.

Empty Carts
When an empty cart is detected, generally it's a good idea to send it into an overflow pile. An overflow pile is a drop of two or more blocks with a rail at the bottom. When carts are boosted into the hole, they will snap to the track, regardless of how many carts are already on the track. This pile should be placed where the carts can be collected, either close to a station or in a maintenance area. It is important to boost carts to full speed just before they are dropped to ensure they don't become stuck on the end of the track and eventually back up the system.

Another variant of this method is to replace the rail at the bottom with a cactus, thus destroying minecarts that fall in. Placement of a hopper next to the sand on which the cactus is placed then allows saving of at least some of the carts.

Boosters
Boosters are a method used to prevent carts from slowing to a stop on a track. Because carts will eventually slow to a halt on level track, and very quickly turn around on regular rail track whilst uphill-bound, boosters are a method of assuring one's cart keeps moving. Boosters accelerate carts to a terminal velocity of 8 m/s, as they use powered rails, and help effectively counter the forces of friction and gravity on the acceleration of the cart. Boosters are simply a single powered segment of powered rail, powered through detector rails, redstone torches or levers next to them. Refer to the diagrams to the right. Players generally keep the distance between boosters uniform, although these distances vary by player. One common, and according to many the most efficient, distribution of powered rails is to place powered rail every 38 blocks on level ground. An easy way to place a lot of track using this count without needing to keep track of each rail is by dividing the rails into stacks of 37, as shown on the right. Approximately 1 out of every 3 rails will need to be powered to travel uphill due to gravity.

Junction
Stations often have one line leading to one destination. Multiple destinations require multiple lines. A junction is a fork in the track where the rider can select which destination he wishes to visit.

This design uses a lever to switch the track and the powered rail will become powered after a preset delay. The detector rail starts the delay. In this design, the lever will always point towards the selected destination regardless of direction.

A junction that has multiple destinations can be set up by expanding the junctions. In the design to the right, the rider is given much more time to select his destination than a two-way junction. He can select any destination by first selecting left or right, then forward or backward. This design doesn't scale well but can be used in sequence to create any number of destinations.

Multiple Destination Selector
There are many, many styles of minecart destination selectors. Most are modular, meaning they can be extended to include more destinations. An RS-NOR latch array is often used to select a destination as these latches have a designated reset line (as opposed to a t-flip flop which only has one input).

This design was selected for its simplicity and for its ability to be expanded with relative ease. One of the buttons on the selection panel is a designated reset line since additional input doesn't clear the previous selection; that is to say, a player can select more than one destination with this design (although a launched minecart will take the left-most of the selected destinations).

by CNB

The following design is heavily influenced by the previous but uses a different RS-NOR latch design involving pistons. It has a reset integrated in the selection such that a new input will clear a previous one. By removing the designated reset line of the previous version, it allows for an additional station in a similar amount of space.

by redminecraftstonetut

Example Of A System Incorporating Some of the Basic Parts
This system consist of a "Launcher", a different mechanism for "Empty Carts", a "Junction" and a "Booster"

System works on tripwire.

The empty minecart is always moving in circles awaiting a passenger. (Empty cart compenent is not needed any longer)

When a passenger is present, tripwire will activate and the rails will switch routes for a few seconds and cart will move away from the station. (Launcher, booster and junction all infused into a simple redstone circuit.)

Troubleshooting
When a track system isn't working properly, it can be difficult to fix for someone unfamiliar with redstone and rails. Common solutions include: Searching on the minecraft forums can help. If you need to create a new post, be sure to include the direction you're working (the F number), as directionality can be a factor in the design.
 * Changing the delay of circuit by adding a repeater or moving a detector rail to trigger earlier.
 * Changing the speed of the minecart by adding powered rails or moving the current ones further away.
 * Checking that powered rails are powered properly.
 * Turn the design around, as direction can affect how it works. Generally this isn't the issue, but it's good to rule it out.