If instructions are received from the employee in charge, who must the train crew contact for route changes?

The correct choice is that the train crew must contact the Employee in Charge for route changes when instructions are received from that individual. This is because the Employee in Charge holds the authority and responsibility for overseeing operations at a specific location or during a particular task. They are the point of contact for train crews regarding any changes, as they are familiar with the current situation and have the situational awareness necessary to convey accurate and appropriate instructions.

The Employee in Charge can provide immediate information related to necessary changes in routes or any other operational adjustments that may need to be made. This ensures that the crew is operating under the guidance of someone who understands the current operational context and can assist them in safely navigating any changes.

In contrast, the other roles, while they may have their functions, do not directly manage the operational decisions concerning route changes initiated by the Employee in Charge in this context.