Well, 'the train life story' might be a story that focuses on the daily operations and the lives of those who work on the train. For example, the train drivers, conductors, and maintenance workers. Their routines, the challenges they face, and the interesting things they see during their work hours could all be part of this story.
The 'train life story' could also be about the history of a particular train. It might start from its construction, how it was designed, and the various purposes it served over the years. It could tell of the different routes it has traveled, the passengers it has carried, and the role it played in different historical periods. For instance, a train that was used during a war to transport troops or supplies would have a very interesting story to tell.
I'm not sure exactly which 'the train life story' you're referring to. It could be about the experiences of people who live on trains, like the homeless sometimes do. Or it could be a fictional story about a train that has a life of its own, with its own adventures and encounters along the tracks.