Minecraft wiki entry for Building_a_rollercoaster, associated text: To maintain top speed throughout your ride, all straight sections of a roller coaster should consist of powered rails activated by means of redstone torches or levers. These redstone power sources can be placed on a block adjacent to or hidden underneath the block that the powered rail is placed on. A single redstone torch or lever will activate 8 connected powered rails in each direction in addition to the rail immediately adjacent to or above it, thus powering up to 17 rails on a track when positioned in the center of a given section. Detector rails can also be used to power 1-3 powered rails when a player is riding the coaster, with the added bonus of sending a redstone signal under or next to the block it's placed on. This creates opportunities for the player to utilize other redstone-powered blocks in their build. Powered activator rails will dismount the player upon passing over one. Only normal rails can guarantee the success of a turn.