Define absolute block.

Define absolute block.

• A. A block that can be occupied by multiple trains
• B. A block controlled by signals only
• C. A block with no trains
• D. Block that must be occupied by 1 train at a time

Answer: (D)

Absolute block means the block is reserved for a single train at a time. A train must have authority to enter, and until that train fully clears the block, no other train may enter. This exclusive occupancy ensures safe separation and prevents two trains from being in the same block simultaneously. The description that a block must be occupied by one train at a time matches this principle. The other options either imply multiple trains in one block, describe only the signaling/control method without the occupancy rule, or refer to a block being empty rather than the exclusive occupancy requirement.

Absolute block means the block is reserved for a single train at a time. A train must have authority to enter, and until that train fully clears the block, no other train may enter. This exclusive occupancy ensures safe separation and prevents two trains from being in the same block simultaneously. The description that a block must be occupied by one train at a time matches this principle. The other options either imply multiple trains in one block, describe only the signaling/control method without the occupancy rule, or refer to a block being empty rather than the exclusive occupancy requirement.