Which statement about how a route is established is correct?

• A. It is determined solely by the signal control logic.
• B. It is determined solely by the operator authority.
• C. It is a fixed route that never changes.
• D. It is established by signal control logic and operator authority.

Answer: (D)

Route establishment is a collaborative process between automatic signal control logic and the operator’s authority. The signaling system’s interlocking and track circuits automatically verify that a path is clear, lock the necessary points, and set signals to permit a train to proceed along a safe route. This automatic control prevents conflicting movements and enforces safety rules. At the same time, the operator’s authority provides oversight, authorization, and the ability to approve non-standard routes, coordinate with traffic management, and override automatic settings when needed for timetable changes, maintenance, or special operations. Because routing depends on both automatic safety checks and human authorization, the statement that it is determined by signal control logic and operator authority is the best description. Routes aren’t fixed, and they aren’t governed by one side alone, which is why the other options don’t fit.