You're walking to class, listening to your favorite music.
Upon arrival, you think, "Hmm. That was about a 3 song walk."
It's a purely unscientific measurement and we all think it.
BeatTripper knows it.
BeatTripper keeps track of your trips in terms of the number of songs you can expect to get out of the walk.
Simply add a route, start the shuffle, and go. BeatTripper will do the rest.