This is the breakdown of locomotive activity within a 24-hour day (based on yearly averages).  The elements in the above diagram constitute, respectively: (1) Locomotive Available: This is the time, expressed in per cent of a 24-hour day that a locomotive could be used for operational service. Conversely, Unavailable is the per centage of the day that a locomotive is being serviced, repaired, re-built or in storage. Locomotive available time plus unavailable time equals 100 per cent; (2) Engine Operating Time: This is the percentage of Locomotive Available time that the diesel engine is turned on. Conversely, Engine Shutdown is the percentage of Locomotive Available time that the diesel engine is turned off; (3) Idle: This is the per cent of the operating time that the engine is operating at idle or low-idle setting. It can be further segregated into Manned Idle (when an operating crew is on-board the locomotive) and Isolate (when the locomotive is unmanned); (4) Duty Cycle: This is the profile of the different locomotive power settings (Low-Idle, Idle, Dynamic Braking, or Notch levels 1 through 8) as per centages of Engine Operating Time