What is a requirement for crews when napping is permitted?

When napping is permitted within a railroad crew, it is required that one crewmember must remain awake. This requirement is crucial for maintaining safety and readiness in operations. Having at least one member alert ensures that there is someone monitoring the situation, responding to any changes or emergencies, and maintaining communication with dispatch or other crew members. This protocol helps to prevent accidents and ensure that the crew can react promptly to any operational needs during the nap period.

The other options do not align with the established guidelines. For instance, all crew members napping simultaneously could leave the train unattended, leading to safety hazards. There is no stipulation that naps must last a specific duration, like one hour, nor is napping restricted solely to designated areas, although following company policies regarding location is important for comfort and legality.