A block signal system wherein the use of each block is governed by an automatic block signal, the cab signal indicator or both?

• A. Block Signal System
• B. Automatic Block Signal System
• C. Manual Block Signal System
• D. Speed Controlled Train

Answer: (B)

This question tests how block usage is controlled by automatic signals and in-cab indications. An Automatic Block Signal System uses track circuits to detect when a block is occupied and sets the automatic block signals accordingly, and it may also provide in-cab information via a cab signal indicator. Some installations use both the automatic track-side signal and the cab indicator to govern block authority. That combination—automatic block signals with optional cab signaling—defines the Automatic Block Signal System.

A generic Block Signal System isn’t specific about automatic operation, a Manual Block Signal System relies on human actions, and Speed Controlled Train isn’t a signaling system type.