Speed refers to elapsed movement time. Airfreight is the fastest of all modes. Availability refers to the ability of a mode to service any given pair of locations. Highway carriers have the greatest availability since they can drive directly to origin and destination points. Dependability refers to potential variance from expected or published delivery schedules. Pipelines, because of their continuous service and limited interference due to weather and congestion, rank highest in dependability. Capability is the ability of a mode to handle any transport requirement, such as load size. Water transport is the most capable. The fanal classification is frequency, which relates to the quantity of scheduled movements. Pipelines, again because of their continuous service between two points, lead all modes in frequency.