"Blue-Flagged." As storm clouds roll in, a five-unit CN A432 from Decatur, Ill., heading for Memphis, Tenn., is holding just outside of downtown Carbondale on April 25, 2015, while a mechanical crew from Centralia is trying to revive the third and fourth units behind the IC SD70s that developed problems north of here. A blue "Safety First" flag is seen next to the train (meaning that the train must not be moved as it is being worked on).