The nature of railroading requires around-the-clock operation. Consequently, railroad personnel responsible for maintaining, servicing and operating this critical sector of the nation's transportation system must work at times outside the weekday hours common in many other industries. Railroad dispatchers are responsible for planning, coordinating and monitoring the safe and efficient movement of trains over the rail network. These employees perform a safety critical job in a time-sensitive environment. Their attention and concentration on routing of trains is key to the efficiency of the railroad's operations and the safety of its employees, the public and the environment.