Minecraft wiki entry for Minecarts, associated text: 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.