I'm still not convinced. I've watched several other videos of the train, and although the notes do change, they are all monotonic. Either someone has "layered" the sound track in a clever way, or someone has added an acoustic system to augment the trains natural tones. In either case, I think it is a pleasant effect, and if not real, it should be added to all electric commuter trains.
Our local e-commuter train used to routinely run over people when it first went into service.
It's name quickly evolved from MAX(Metro Area eXpress) to Mad Max.
Actually, listening to the following, I just realized that if two trains were leaving at once, it might create the same effect. But I think the timing would have to be perfect to get them to make harmonious music, as in Dave's video.
Eisenbahn Musik - Taurus Tonleiter - Musical Train Engines
Published on Jun 18, 2013
Taurus Tonleiter - Lokomotive macht Musik
E-Lok Baureihe 182 der DB
ÖBB BR 1016 1116
Siemens ES64U2 - Elektrolokomotive Abfahrt
Musical Train Engines - Electric Locomotive
Zuggeräusche Eisenbahn Taurus
ps. If anyone is really bored, you can watch the following.
14 ½ minutes of listening to LOTS of these trains leave the station.