Block(air brakes) : A group of cars that have had the air brakes tested and been disconnected from an air pressure source for less than four hours.
Block (electrical) : A section of track that is electrically isolated for control or for signaling.
Block (operations) : n -A group of cars that will be handled together as they move across the railroad. Cars are sorted in yards and grouped together in blocks for efficient handling. Bocks may share a common destination, a common car type, a common commodity or may be cars that will be switched at the same next yard. v- to sort cars into blocks.