Minecraft wiki entry for Powered_Rail, associated text: 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 continues 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 turns east or south (depending on the powered rail's orientation), or in the downward direction for a slanted powered rail.