If there is a train sitting on the track at Double Tunnels for a long time, here is what you do.
Turn around and go back the way you came to the Fulton County Animal Shelter.
Just as you get back to Animal Shelter, GEORGIA POWER is to your right and a little access road on your left, take that access road which quickly dumps out onto Marietta Boulevard where you will go left.
Watch out for cars as it can be a busy street.
Bang a hard right to go back under the bridge on a gravel and dirt and to get back on railroad tracks.