What does it mean to "flag" a crossing?

"Flagging" a crossing refers to the act of providing warning and traffic control to ensure the safety of both trains and motorists at a railroad crossing. This typically involves a trained individual, often referred to as a flagger, who signals to oncoming traffic when it is safe to proceed or when it is necessary to stop due to an approaching train. The flagger may use visual signals such as flags or lights and may also use verbal commands or other methods of communication to maintain safety at the crossing.

This process is crucial in reducing the risk of accidents and ensuring that vehicles are managed properly when trains are approaching. The need for flagging becomes especially apparent in situations where visibility is limited or when signals indicating the presence of a train may be malfunctioning.