What is required for a train to pass an interlocking signal that is displaying a stop signal?

For a train to pass an interlocking signal that is displaying a stop signal, it is necessary to have both specific written permission (Form L permission) and verbal confirmation. This requirement ensures that the train crew receives clear and documented authorization to proceed past a stop signal, which is critical for maintaining safety and operational integrity. The combination of these two types of permissions is designed to prevent misunderstandings and ensure that all personnel are aware of the train's movement in potentially hazardous situations.

Verbal communication alone is not sufficient, as it lacks the formal documentation needed for accountability and clarity. Similarly, relying solely on Form L permission without the verbal confirmation would not provide the immediate assurance of situational awareness that verbal communication affords. Therefore, both forms of permission are essential for safely authorizing a train to move past a stop signal at an interlocking.