A lot of comments commenting on never having heard the sound but also then criticizing the sound. Trust me, it sounds different in real life from what you can hear in the video and there's no way you'd confuse it with air brakes with it's constant short bursts of sound anyway, unless the air breaks are really funky in which case you should be looking anyway. I also find it funny that people are saying they won't look at the sound of air breaks because that means a vehicle is stopping so you don't have to look, not even considering it might have stopped because you're in the way if that was what it was. I hope you people aren't actually that unobservant of the world around you.