I mean, a train's pretty big and it's easy to spot.
As Rosario Dawson's train controller character says, "it's [like a] missile the size of the Chrysler building".
It's their first day working together and it doesn't start well as the two don't get along.
An idiot of a train engineer who's supposed to be moving a train inside the train yard, let's the train get away from him, under power, and it starts building speed on a main line in Pennsylvania, soon cruising out of control.
Just to make matters more interesting, it's revealed that several cars on the train contain a flammable explosive.
Adding human interest to the story are Denzel Washington and Chris Pine.
Pine plays Will, a new train conductor, while Washington is 28 year veteran, Frank.
The "villain" of the piece, Glavin, is a bit of a stereotype, more concerned with saving the company money than saving people's lives, but it doesn't hurt the story.