What action must be taken if radio communication fails before a Form D is given a Time Effective?

When radio communication fails before a Form D is given a Time Effective, it is important to proceed with caution until communication is reestablished. The correct action in this scenario is to proceed only after communication is reestablished. This is crucial because the Form D is a critical operational document that contains instructions and restrictions specific to the movement of trains. If the communication is down, there is no confirmation that all involved parties are aware of the restrictions or conditions affecting train movements, which could lead to safety hazards or operational errors.

Ensuring that communication is reestablished before proceeding helps maintain safety protocols and allows for proper coordination among train crews and dispatchers. Other actions, such as waiting for written permission to proceed or assuming trains can continue without restrictions, may expose crews and operations to unnecessary risks, especially in situations where essential information is not communicated effectively.