Railroad crossing bells are a familiar real-world warning sound, used at level crossings to alert drivers and pedestrians that a train is approaching. Because the pattern is instantly recognisable, it has become a staple stock effect for film, television and online video, where it instantly establishes a railway setting without needing any visual explanation. On soundboards it is commonly shared as a short, loopable ambience clip for train videos, roleplay scenes, animation and meme edits that play on the idea of something unstoppable coming down the track.