How should a train respond to a signal indicating it can pass?

When a train encounters a signal indicating it can pass, it is essential to ensure that it corresponds to one of the specified signal numbers. This is critical because signal systems are designed to communicate specific instructions to train operators regarding track conditions, safety, and the status of the route ahead. Each signal number corresponds to a defined set of rules that govern the train's operations.

Understanding the signal designation is crucial because it affects the train's subsequent actions and safety protocols. A clear understanding of which signals permit passage ensures that the train operator is not about to proceed into potentially hazardous conditions or areas of track that are unsafe for travel. It reinforces adherence to signal protocols that have been established for the safety of the train and passengers.

In contrast, other options suggest actions that are less aligned with proper signaling practice. Simply maintaining current speed does not account for signal interpretation, and stopping only after seeing the signal might lead to unnecessary delays. Likewise, reversing back to the last signal could create safety issues and disrupt train schedules, which is contrary to the operational protocols designed to manage rail traffic safely and efficiently.