A Union Pacific worker passes an SD90MAC (UP calls them SD9043AC) with some blue flags in the heart of the railroad's Davidson Yard in Fort Worth, Texas, on October 16th, 2011. (Blue Flags are used by railroads to protect employees who are working on equipment. The equipment cannot be moved as long as the blue flag is in place, and it can only be removed by the employee who placed it on the equipment.) Photo taken on railroad property with permission and while wearing required safety gear (PPE).
