What term describes a length of track with defined limits whose use is governed by block signals, block-limit signals, automatic speed control, or any combination thereof?

• A. Block
• B. Absolute Block
• C. Automatic Block Signal System
• D. Manual Block Signal System

Answer: (A)

A block is a defined length of track separated from adjacent sections and governed by signals or automatic controls to manage entry and occupancy. This unit is the basic subdivision used in signaling, and the phrase “governed by block signals, block-limit signals, automatic speed control, or any combination thereof” describes how the block is controlled, not a different kind of track.

Absolute Block is a stricter form of block signaling where only one train may occupy a block and explicit authority is required to enter the next block. Automatic Block Signal System refers to an arrangement where signals operate automatically based on occupancy detected by track circuits. Manual Block Signal System relies on a dispatcher or operator issuing block authority. All of these are methods of controlling the same block, the basic track segment, which is why the correct term is block.