This site links to maps of the class I railroads in the USA.  These maps allow you to download KMZ files of the railroads' districts/subdivisions into Google Earth and simulate flying over the tracks in a P-51 Mustang at 325 mph at an approximate altitude of 1200 feet.

You may also use Garmin Basecamp to convert the KMZ files to "routes" and load the routes to your Garmin GPS device's "Trip Planner".