What signal is used in the subway to notify a motorman to proceed?

In the context of subway operations, a white lantern is utilized to indicate to a motorman that they may proceed. This signal communicates a clear and explicit permission to move forward, assuring the operator that the track ahead is clear of obstacles or hazards.

In railway signaling systems, the use of different colored lanterns or lights serves specific purposes. For instance, a red lantern typically signifies a stop or danger condition, alerting the motorman to halt the train to avoid potential risks. Green lights or lanterns often indicate caution or a slower speed may be required, rather than a full go-ahead. Similarly, blue lanterns are sometimes used for maintenance work or notifying operators of work zones, not for normal operating signals.

Therefore, the use of a white lantern effectively conveys the essential message for safe and efficient train movement in subway operations.