What does a blue flag indicate?

A blue flag indicates that there are men working on or about the train equipment, and it serves as a critical safety measure in the railway industry. The flag acts as a warning to all train operators and crew members that they must stop and not proceed until the blue flag is removed. This practice is essential to ensure the safety of workers who may be performing maintenance or repairs on the equipment, thereby preventing accidents and ensuring that appropriate safety protocols are followed within the work zone. The presence of the blue flag is a clear visual signal that necessitates immediate attention and cautious operation until the all-clear signal is given.