Rail

Rails are non-solid blocks that provide a path along which minecarts can travel.

Obtaining
Rails can be mined with anything, but pickaxes are the quickest.

They also drop as items when:
 * the block beneath them falls, is moved, or removed
 * a liquid flows over them
 * a piston moves them into a space with no floor below them

Natural generation
Rails can be found naturally running along the floors of abandoned mineshafts and in woodland mansions.

Usage
A rail can be used as a minecart track and as a redstone component. A sequence of rails (including regular rails, activator rails, detector rails, and powered rails) is called a track.

Placement
To place a rail, a rail item while pointing at a surface facing the space the rail should occupy. A 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 rail cannot be attached to the side or bottom of any block, but attempting to make such an attachment may cause the 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 rail to the side of the fence will cause the rail to be attached to the top of the ground next to the fence instead.

When placed a rail will configure itself to be straight or curved according to rail blocks around it.
 * If there are no other rails adjacent it will be placed as a straight track oriented north-south.
 * If placed at the end of an existing stretch of track, the new rail will be a straight track section oriented to continue the existing track, either east-west or north-south.
 * If placed beside an existing stretch of track (of any type) the newly placed rail will be straight and oriented north-south.
 * If there are two adjacent rails on its level, or one level up or down, the newly placed rail will configure itself to connect the other two. This means that it will be placed as a straight or curved track as needed.
 * If placed between three adjacent rails (thus always forming a T-junction) the newly placed rail will be placed as a curved track south-to-east, north-to-east, or south-to-west to join those sides.

Existing sections of track may be re-oriented, become sloping, or even change into curved sections when new rail is placed adjacent to:
 * An existing straight, north-south rail will re-orient to east-west when a new block is placed to its east or west sides.
 * If placed next to an existing rail that is one block up or down the rail will slant up or down to join it. Rail "prefers", in order: west, east, south, and north. Other configurations can be created by placing and removing rails.
 * If a track is placed perpendicular to an existing length of track it will show as a straight rail, but in fact will be curved according to the patterns for tee junctions as seen above and mine carts going through the intersection will turn the corner. Breaking and re-laying track so that the intersection block is laid last will update the intersection block as a curved section.

Redstone component
The intersection rail at a T-intersection may be made to change its direction of curvature by applying redstone power using a redstone torch or lever.

Separate tracks laid adjacent but at the next level lower or higher can sometimes cause issues but normally will not interact with the switched rail.

South-east rule


When entering a T-shaped intersection from the "back of" the curved rail a mine cart will travel straight through the intersection. Entering from either of the other two legs it will follow the curve.

In a 4-way intersection constructed to have no curved rail a cart will pass straight through in the direction of the continuous line. When entering the 4-way from east or west a cart will turn according to the south-east rule.

Downhill rule


At non-curve track intersections minecarts will always travel downhill if they can. This is known as the downhill rule and overrides the south-east rule.

Ramp clearance/one-way effect


A block placed above the track at the downhill end of a ramp will prevent minecarts from traveling down the slope, but not up. In order for a minecart to move down a diagonal tunnel, there must be just as much clearance as a player needs to walk it.

Curve intersections


If a straight track piece leads to a curve block and isn't attached to the curve, a minecart will run over the gap and continue to go straight over the curve. This is not applicable with other types of rails.

Notably, the minecart can exceed the normal 8 m/s speed limit while it jumps over the gap. For example, by placing intersections on every other block of a straight track, it is possible to travel at 10 m/s in a straight direction (but it will be a very uncomfortable ride).

As with straight T-intersections and 4-way intersections, the practice of making a minecart jump tracks can be used to make one-way entries onto a track. On curve intersections the behavior is a lot more intuitive, though, since the cart will simply proceed in the direction it is already going, allowing designs that don't rely on knowledge of the south-east rule.

Rail performance
A minecart with no rider at full speed can climb 10 blocks on unpowered track. This suggests that a powered track is only needed at a height of 10 blocks to keep a cart climbing. However, the cart slows so much that it can only reach another 5 blocks high with 2 lengths of powered track starting at 9 blocks high. The minimum number of powered rails to keep the cart climbing is 3 every 6 blocks.

Carts with a rider, or minecarts with chest, have more momentum and so climb higher than carts that are unloaded. With a rider, a minecart can climb at least 24 blocks before needing powered rails to go higher. And to ascend from 0 to max speed, you need 7 powered rails.

Data values
Every rail has an ID name of  and stores its orientation in its block data. A rail also has a block state which is expected to replace the functionality of block data in a future version.

Block data
A rail's block data specifies the directions to which it connects.

Trivia

 * When walking on a block that has a rail on top, you will hear the sound of the block you're walking on, but if you jump (while still walking), you will hear the sound of iron.
 * Rails are 750 mm (approx. 2-foot 5-inch) narrow gauge. (The gauge is the distance between the rails.)
 * Rails will visually block off a large portion of the block behind them when said block is highlighted, a bug which Mojang decided not to fix.