What are "block signals" used for?

Block signals are primarily used to communicate the status of the track ahead to train operators. This is crucial for maintaining safe and efficient railway operations. By displaying the conditions of the blocks of track in front of a train—whether they are clear, occupied, or out of service—block signals help train crews make informed decisions about speed, stopping, and overall operational safety.

The focus of block signals is on ensuring that trains are not running into occupied sections of track, which is fundamental for preventing collisions and maintaining a controlled flow of rail traffic. This system is a core part of signalization in railroads, allowing for the effective management of train movements over vast distances and complex routes.

The other options, while related to railroad operations, do not accurately describe the primary function of block signals. They serve different purposes in the context of railway systems, such as passenger communication or maintenance scheduling, but none replace the essential role of block signals in conveying track status directly to train crews.