Actually, trains can be surprisingly quiet. A group of us were out riding one night in Chatsworth, CA. We had to cross a railroad track to get to the trail we were going to use. As we were walking the horses across, there was this funny, humming noise coming from our left. I looked up and the train had just come around the bend, about 100 yards away from us. Lemme tell ya... Spurs save lives! It was spooky how quiet that train was.
The Dopler Effect.