ask the audience24 May 2007
Question for the locomotive engineers in the audience (come oooon, I know you’re out there!):
When you see a train idle on the tracks, you hear a clicking noise – sounds electric, like the noise that you get when you click two ends of jumper cables together when they are hooked up to a battery (don’t make a habit of doing this). It’s an irregular pattern, though, with erratic delays and speedups in the frequency.
What is this noise?