I used to have this recurring dream in the past. It's very comfortable and pleasant, almost ethereal.
The dream is set in a forested campground of some sorts, although signs of anyone camping there are present. There are train tracks running through the area. The tracks seem brand new, as if they've been laid very recently. I'm standing right on the tracks (on one of the rails), talking to a girl who's standing next to the tracks. She seems very friendly and warm, making me feel completely as ease right from the start. Suddenly, I hear the sound of a train rumbling in the distance. At that point, the girl grabs me by the wrist, gives it a light pool, and says in a soothing voice: "hey, there's a train coming". I step off the tracks, and the train passes by. Once the train is gone, I'm about to thank the girl for saving me, and try to get to know her better. Unfortunately, that's when I wake up.