Powered Rail

The Powered Rail is a block that is used to stop or increase momentum of moving carts. It was added as response to bug boosting. It is noteworthy that the glitch boosters currently still function. It's operated by Redstone currents.

In its unpowered state, it acts as brakes for any minecart which crosses its tile. In its powered state it will accelerate the cart passing over them. A notable exception to this rule is a Powered rail which has a solid block on either end which will boost a cart from standstill when activated.

The speed of a cart which is boosted using Powered Rail is calculated to be at a maximum speed of 8 m/s, but it can have more momentum than needed, allowing longer travel times.

Crafting
Powered Rails are made somewhat differently from normal rails; using gold instead of iron, and adding redstone to the bottom.

Effects
Powered rails, much like redstone wire, 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.

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 like they would on pressure plates.

Powering
Power can be transmitted to the rail from any of the six adjacent positions (above, below, or any side) in the same ways that redstone wire is powered. Strangely, the rail can also receive power from the five positions immediately above those adjacent positions. In other words, the rail acts as if it is two blocks high, and can receive power through any of eleven adjacent spaces, just like a door. This works whether the upper space is occupied or empty. However, powering the rail through the upper space currently exhibits more bugs related to updating.

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 rail (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 Switch next to the powered rail

It needs to be noted that currently the rail needs to be placed before the power source for it to work. If you dig a hole 2 blocks down and place a redstone torch inside followed by a block on top any rail you place on top will not appear to be active; however there are some workarounds for this.

Optimal use
A (single, sloped down) powered rail boost gives an occupied cart enough momentum to travel 64 tiles on a flat surface, or 8 tiles for an unoccupied cart. It is usually impractical and expensive to place powered rails one after the other. Instead, space powered rails out at regular intervals once the cart is traveling at speed. Four powered rails in a row are sufficient to boost a cart to max speed.

An example station would be a block, a powered rail with a stone button, a regular rail, then 4 continuously powered rails. An example of this type of station is shown in the Effects section, above.

This above station has certain benefits such as the launcher and the speed it gets to. But would be impractical in multiplayer because a collision will occur if two people use it at the same time. However, once at speed, the optimal spacing of powered rails on a level track is to use 1 every 26 blocks (that is, a repeating pattern of one powered rail followed by 25 normal rails, then another powered rail, and so on) which maintains a constant minecart speed of 8 m/s. If gold is in short supply, it is possible to use powered rails with more space between them at a cost of a reduced overall speed: By using 1 powered rail every 26 blocks, you can easily match this with using one standard torch every 13 blocks which keeps the entire track at light level 7 and above since hostile mobs can spawn on tracks (non-hostile mobs will only spawn on tracks if the track is on dirt with green grass).
 * One powered rail every 30 blocks: 7.8 m/s– 2.6% speed decrease
 * One powered rail every 32 blocks: 7.2 m/s– 10% speed decrease

Diagonal travel
Because 'diagonally' laid down tracks (meaning a track consisting of the pattern; left corner attached to a right corner attached to a left corner ... and so on) already showed a difference with normal rails on the distance and speed there was reason to test the properties of such tracks when the cart was powered by powered rail.

For diagonal tracks on level ground, the optimal spacing of powered rails is 1 every 36 blocks (counting orthogonally, if you count diagonally instead it is 1 every 18 blocks). It is worth noting that 36 is roughly equal to 26 multiplied by the square root of 2, which is the actual distance one would travel diagonally (by Euclidean math) if a player moved 26 blocks on both coordinate axes.

Momentum
Minecarts have both a speed and a momentum. While your top speed may be 8 m/s, having a higher momentum will allow you to travel at that speed for longer periods of time. Having a minecart in a small 3x3 powered loop for a period of time can give a considerable boost in momentum, resulting in a very long travel distance at the speed limit until all the surplus momentum gets used.

Tests show that slopes impact the momentum severely, and thus the speed plummets fast but if there is enough surplus momentum it is viable to travel up slopes with ease.

Climbing slopes
The chapter below assumes carts that do not have this surplus momentum and is to get some benchmark values.

Launching from rest via four powered rails, an occupied cart has enough momentum to climb a 1/1 slope six 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 a seven block high slope. An unmanned cart in a similar setup will only climb three blocks and then travel a few blocks horizontally.

A pitfall that people might initially fall into could be placing a powered rail every (other) block to maintain the speed. This means that when using this example for every two blocks of height climbed, a gold ingot is required and this has likely been the cause for complaints about the powered rail being 'broken'. There is however a great way to travel higher up a slope and that is to have more momentum to begin with.

Inversely to the fact that sloped up tracks decrease the momentum rapidly, sloped down tracks add more momentum to the boost by comparison. For example 3 sloped down powered before a slope up consisting of normal track gives approximately the same elevation as 6 level powered rail.

An example showing you can easy reach more altitude is shown In the Powered Rail Mechanisms section

Use with Detector Rails
A Detector Rail will power the 4 blocks adjacent to it as well as the 2 blocks below it when a minecart (both occupied or empty) is over it. It is thus possible to activate powered rails inline without the use of redstone torches or wiring.

In general it is possible to include a detector as a source to get the power to activate an adjacent powered rail but this is not recommended as best practice. For example if you place one detector and 4 subsequent powered rail you will see the cart gets stuck on the third or second powered rail since the moment the detector stops detecting the cart the power will get cut instantly and the powered rails return to their braking behavior.

However when just a single powered rail is used in combination with a detector in theory this lends itself to one-way powered rail lines by placing a detector rail before the powered rail (with respect to the desired direction of travel). This way, occupied carts will only be boosted if they are traveling the proper direction. Carts coming from the "wrong" way will be quickly brought to a stop by the inactive power rail. Notice however that when using this as described there will be a cart stuck on the track. The most likely way this is used in practice is not to block a wrong way cart but because the track is designed so there is only one way possible to start with.

A two-way line can be inefficiently created by placing detector rails on either side of the powered rail. In practice when choosing detectors to give power on a two-way track you will need a detector on either side of a single powered rail. Although they do work and can be effective for some specific reasons to give power inline it is not often used this way.

Placing alternate powered and detector rails up a 1/1 slope will not propel a cart more than 3 blocks upward if there was little momentum to start with, because the cart will be slowed down by the slope and fails to clear the powered rail before it returns to the "off" state due to the fact that the cart is no longer over the detector. The cart will become stuck unless it is in a "train" of two or more carts, in which case the last cart in the train will become stuck.

A better example to use detector rail would be have something activated or changed based on where the cart is in your track, or as failsafe devices. For example if you have a station with a cart waiting if may be a good idea to release the cart waiting at a station in case a rogue cart arrives instead of having both collide.

Additional properties
Curved power rails currently only exist in the case of a T-junction. They do not currently function like regular rails in a curve (without being in a junction). 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
 * 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.

Starting boost
Creating 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 mine cart will be boosted out.

Momentum boost /climb boost
A discussion in the minecraft forum shows it is possible to reach a remarkable height with just using 4 powered rail

The example shown is a 3x3 loop with 4 powered rail Which in turn is connected with a T switch to the slope. A cart is placed on the loop and allowed to spin around for a few seconds to build up momentum beyond the speed limit. The best practice is to have a pressure plate switch the T section to form the loop. So when the cart has sufficient momentum the player steps inside, because the pressure plate is then deactivated the loop switches so the cart goes onto the normal track and subsequently the player starts to move onto the sloped part of the track.

With just a few seconds of building up momentum, you will reach the cloud layer if sea level was used as starting point.

Bugs

 * If a Powered rail is only powered by another Powered rail diagonally up or down, you can destroy the rail powering it and it will continue to look and act like it has power until the block is updated. This can be used to have little to no power sources in your track design and up to 2/3 less powered tracks for uphill parts.
 * When you power a track, 8 tracks in both directions (excluding the track being powered) will be powered. If you have a 19 Powered tracks in a row [1,2,3...18,19] and you Power track 10, tracks 2-9 and 11-18 will receive power. If you add power to track 9, after powering track 9, track 1 will not be powered, even though it is within the 8 tracks. After this, if you remove power from track 10, power will be taken from track 9, however, the same tracks will be stay powered (tracks 1 which should be powered is not, and track 18 which is powered, should be unlit). If you power track 2, (or 18), you will get power in the next 8 blocks.
 * Doing this, you can power infinite tracks with only 3 torches. 1) If you power track 1, up to track 9 will be lit. 2) Power track track 9 (or last lit track) and 10 (the last unlit track). Putting power in track 9 will keep the previous tracks lit, and 10 will power the next. 3) Then unpower 1, it will still be lit, as 9 is lit, and in the 8 range. 4) Now unpower 9. 1 is still lit. Jump back to step 2.
 * This also means you can't power tracks in steps of 1 (unless you make something fancy with redstone circuitry). You would have to unpower everything, then power the one 8 steps away (you need n carts + 8 for the number of tracks)
 * There are currently no textures for curved power rails. However, they still work when placed at T-junctions powered by Redstone.

Trivia

 * For comparison of speeds, walking speed is about 4 m/s (4.27 exactly), thus using powered rail to speed up will almost double your traveling speed.
 * Powered rails will always show as powered in the inventory even if destroyed and collected while it was unpowered.
 * Noting that it takes 6 Gold Ingots to make 6 Powered Rails, it might be more resourceful to use bug boosters. However, bug boosters will no longer function in the upcoming patch 1.6.
 * When a powered rail with power has another powered rail added next to it, the second rail will not light, until the power is reset.