What is the term for when no train is allowed to enter a block while another train is in the block?

• A. Absolute Block
• B. Emergency
• C. Consist
• D. Coupler

Answer: (A)

Absolute Block is a railway signaling method in which a defined track section, or block, is considered blocked as soon as a train occupies it. Entry to that block is prohibited while it’s occupied, so the following train must wait at the protecting signal until the block is clear. This guarantees that only one train stays in a block at a time, providing safe separation and preventing rear-end collisions. Occupancy is detected by track circuits or other detectors, and the interlocking prevents signals from allowing entry into a block that’s still occupied. The other terms don’t fit this concept: an emergency is about urgent stop situations, a train’s consist refers to its cars, and a coupler is the device connecting cars.