What does 'BLOCK LIMIT' indicate?

'BLOCK LIMIT' refers specifically to an area where a block limit signal is displayed. This signal indicates the limits of a block section where trains must adhere to specific operational rules. It serves as an essential part of train movement control, helping to maintain safe distances between trains.

In railway operations, the block system divides the track into segments (blocks) to regulate train movements and ensure safety. The block limit signals help to communicate critical information about when it is safe for a train to proceed or when it must stop. This concept is crucial for preventing collisions and ensuring the orderly flow of rail traffic.

Locations of control towers, places where trains are stationed, and areas designated for maintenance work relate to different aspects of railway operations but do not specifically delineate the operational limits where the block limit signal governs train movements. Thus, understanding the significance of the block limit signal in regulating train operations highlights why this option is correct.