What is a Signal, Block?

What is a Signal, Block?

• A. A moving signal on the locomotive.
• B. A fixed signal at the entrance of a block that governs trains entering and using that block. NOTE: Block signals are also called 'intermediate' signals.
• C. A hand signal used by the flagger.
• D. A float in a water block.

Answer: (B)

A block signal is a fixed device placed at the entrance to a defined section of track (a block) that tells a train whether it may enter and proceed through that block. It governs entry and how the block will be used, so trains don’t collide by occupying the same block at the same time. In many systems these signals are also called intermediate signals. This is the best description because it reflects that the signal is a stationary, trackside authority at the start of a block, controlling entry into that block and the movement within it. The other options describe concepts that aren’t block signals: a moving signal on the locomotive isn’t how a block signal is defined; a flagger’s hand signal is a human communication method used in certain operations, not the fixed block signal; and a float in a water block is unrelated to railway signaling.

A block signal is a fixed device placed at the entrance to a defined section of track (a block) that tells a train whether it may enter and proceed through that block. It governs entry and how the block will be used, so trains don’t collide by occupying the same block at the same time. In many systems these signals are also called intermediate signals.

This is the best description because it reflects that the signal is a stationary, trackside authority at the start of a block, controlling entry into that block and the movement within it. The other options describe concepts that aren’t block signals: a moving signal on the locomotive isn’t how a block signal is defined; a flagger’s hand signal is a human communication method used in certain operations, not the fixed block signal; and a float in a water block is unrelated to railway signaling.