What primarily dictates the functioning of "controlled track"?

The functioning of "controlled track" is primarily dictated by signals and instructions from the Rail Traffic Controller (RTC). In this system, the RTC plays a crucial role in managing train movements and maintaining safety and efficiency on the tracks. Signals provided by the RTC indicate when a train can proceed or must stop, ensuring that all trains operate in a synchronized manner, thereby preventing collisions and other accidents.

The instructions from the RTC also adapt to various factors like train schedules, weather conditions, and track maintenance, allowing for real-time adjustments. This centralized control helps to optimize the usage of the track network, making managed operations more effective and responsive to changing conditions.

Other options, such as manual operation by train crews, do play a role in train operations, but they are generally supplementary to the overarching control provided by the RTC. Regular maintenance checks and physical barriers, while essential for safety and infrastructure integrity, do not dictate the real-time operational dynamics as effectively as the signals and instructions from the RTC. Thus, the RTC's commands are foundational to how controlled tracks function.