When the park's train attraction was down for an extended period, I had the chance to create new theming and build a custom on-ride audio system. The station and queue were refreshed with ambient telegraph audio hinting at train robbers, plus nods to the park railroad's 60+ year history. Along the route I built a faux Model T, and the tunnel gained themed signage and a burning-fuse illusion.
The audio system needs no operator input. Two inductive proximity sensors beneath the train chassis detect metal flag plates along the track and trigger matching cues. Background music plays continuously while narration layers in dynamically, with timing that adapts to the train's speed. A secondary “homing” sensor resets the system at the end of each cycle.