Train horns have long served as warning signals at crossings and along railway lines, and their loud, instantly recognisable tone has made them a staple of film, television, and online video. On soundboards and in short-form edits, the sound is often lifted out of that railway context and used as a comic or dramatic cue, signalling arrival, departure, or an interruption. Because almost everyone recognises it immediately, it works without explanation, which is why creators keep returning to it for travel content, reaction clips, and alert-style notifications.