For an especially deadly setup, place a powered Priming Track and then a powered Launcher Track in consecutive order after a short line of normal Tracks, and then place a TNT Cart on it and give it a little push. Fuse length and launch power can be adjusted with a Crowbar.
TNT Cart can be exploded directly by letting it go down unpowered elevator tracks. It explodes upon reaching the last elevator track. It will not explode if it is carried up the elevator tracks (powered elevator tracks).
WARNING: If you put the TNT cart on high speed rails it will explode when it hits the launcher or the primer because it is going too fast