What does "block signaling" refer to in railroad communication?

"Block signaling" refers to a system that uses signals to indicate whether a section of track is occupied or free. This is a fundamental component of railroad operations that ensures safe train movements. The signaling system divides the railroad track into segments known as blocks, and each block can be monitored to determine its status. When a train occupies a block, signals indicate that the block is occupied, preventing other trains from entering the same block until it is clear. This system helps maintain safe distances between trains, reducing the risk of collisions and enhancing overall operational efficiency.

In contrast, the other options do not accurately describe block signaling. While tracking train speeds is important for operational safety and efficiency, it does not directly pertain to the function of signals in indicating block occupancy. Marketing techniques for train services and protocols for passenger announcements are also unrelated to the technical signaling aspect of railroad communication.