Minecraft wiki entry for Building_a_rollercoaster, associated text: Tunnels allow you to move a rider safely through an obstacle, including natural features of the terrain, such as a mountain, water, or lava, the Nether, or anywhere else that an obstacle would otherwise block the way. If the roller coaster moves through The End, there is no way to protect the rider from the dragon without killing or teleporting it away when it draws near (which requires complex commands), except for a tunnel constructed fully of bedrock, which is impossible to obtain in Survival mode without the use of glitches.