What must be done if a dispatcher needs to authorize a TC through a work zone?

When a dispatcher needs to authorize a through train movement in a work zone, completing a Form D is essential because it serves as an official documentation of the specific authorization granted. This form provides critical details regarding the train's movement, including the limits of the work zone and any conditions that need to be observed during the passage.

Using Form D ensures that all parties involved have a clear and uniform understanding of the authorization. It also acts as a formal record that can be referred to if any issues arise regarding the movement. This procedure underscores the importance of clear communication and documentation in a potentially hazardous environment, such as a work zone, where safety is paramount.

In contrast, notifying the maintenance crew alone would not suffice, as it does not provide the formal authorization needed for train movements. Verbal authorization may lead to misunderstandings or miscommunication, which is risky in operational contexts. Measuring the track gauge, while important for safety, is not directly related to the process of authorizing train movements through a work zone. Thus, completing a Form D is the necessary step to ensure everything is documented properly and safely managed.