I'm not sure what it is about taking photos of train tracks, but I'm All ABOARD! (haha - get it? trains and the term 'all aboard'? - I crack myself up sometimes!)!
For me, the fascination with photographing train tracks is the depth of field you get with the train tracks fading away in the background giving your photo interesting depth, take your camera lower to the track to photograph an interesting perspective too.
I realize that taking photos on train tracks may be dangerous and even against the law in some areas . . . please be safe and use good judgement.