Powered Rail

A powered rail is a type of rail that is used to decrease or increase the velocity of moving minecarts.

Obtaining
Powered rails can be crafted and previously-placed powered rails can be broken with bare hands or any tool, dropping themselves as items. To remove a powered rail, it:

A powered rail will also be removed and drop itself as an item:
 * if the block beneath it is moved, removed, or destroyed
 * if water flows into the powered rail's space
 * if a piston tries to move it vertically, or if there is no block beneath it at the new position after a horizontal move

If lava flows into a powered rail's space, the powered rail will be destroyed while the lava burns the dropped rail instantly, preventing the player from retrieving it.

Usage
A powered rail can be used as a rail and as a redstone component.

To place a powered rail, a powered rail item while pointing at a surface facing the space the powered rail should occupy. A powered rail can be placed on:
 * the top of any full solid opaque block (stone, dirt, blocks of gold, etc.), including full-block mechanism components (command blocks, dispensers, droppers, note blocks, and redstone lamps)
 * the top of a hopper, upside-down slab, or upside-down stairs.

A powered rail cannot be attached to the side or bottom of any block, but attempting to make such an attachment may cause the powered rail to attach to the top of a block under the destination space. For example, if a fence is on the ground, attempting to attach a powered rail to the side of the fence will cause the powered rail to be attached to the top of the ground next to the fence instead.

When placed, a powered rail will configure itself to line up with any adjacent rails (including activator rails, detector rails, and other powered rails), as well as adjacent rails one block up. If there are two adjacent rails on non-opposite sides, or three or more adjacent rails, a powered rail will line up in the east-west direction. If there are no adjacent rails, a powered rail will line up in the north-south direction (but if a rail is later placed to the east or west, the powered rail will re-orient itself in the east-west direction even if it is already connected to another rail to the north or south). If a rail it would line up with is one block up, a powered rail will slant upwards towards it (with multiple options to slant upwards to, a powered rail "prefers", in order: west, east, south, and north). Other configurations can be created by placing and removing various rails.

Rail
Powered rails (and other rails) can be used as "roads" for minecarts. A minecart that enters a powered rail's space from either end of the powered rail will continue to move in the direction the powered rail is facing, but its speed may change depending on whether the powered rail is active or not (see below). A minecart that enters a powered rail's space from the side will turn east or south (depending on the powered rail's orientation), or in the downward direction for a slanted powered rail.

Redstone component
Powered rails can be used to affect the speed of minecarts that travel over them.


 * Activation


 * A powered rail is a redstone mechanism and can be activated by:
 * an adjacent active power component (for example, a redstone torch, a block of redstone, a daylight sensor, etc.)
 * an adjacent powered block (strongly-powered or weakly-powered)
 * a powered redstone comparator or redstone repeater facing the powered rail
 * powered redstone dust configured to point at the powered rail, or a directionless "dot" next to it; a powered rail is not activated by adjacent powered redstone dust which is configured to point in another direction.


 * An activated powered rail will also activate any adjacent powered rails it is connected to, up to eight away from the original activation source. Thus a single activation source can activate up to 17 rails (one original in the middle and eight on either side). An activated powered rail will not activate adjacent rails which it is not connected to.


 * Behavior


 * An active powered rail will:
 * increase the speed of a moving minecart in the direction it is already moving
 * accelerate a non-moving minecart away from a solid opaque block the powered rail is facing (so a non-moving minecart will move away from the block when the powered rail activates, and a moving minecart will "bounce" off of a block an active powered rail is facing because it stops and then gets accelerated away)


 * An inactive powered rail will reduce the speed of a moving minecart, usually stopping it within one block's distance even on a downward-slanted track. If a slanted powered rail activates with a non-moving minecart on it, the minecart will start moving downwards (because it is no longer being braked by an inactive powered rail) and will then be accelerated downwards.


 * Powered rails cannot increase the speed of a minecart to more than 8 blocks per second on either the north-south or east-west axis. The speeds that can be achieved with varying numbers of powered rails or intervals of normal rails between powered rails is complex -- for a thorough discussion, see Tutorials/Minecarts.

Trivia

 * Powered rails were originally a suggestion for golden tracks.