What should be done if someone is not clear of the yellow safety line on station platforms?

Sounding the horn continuously is the appropriate action to take when there is an individual not clear of the yellow safety line on station platforms. This action serves as a crucial warning not only to the individual but also to others nearby. The yellow safety line is designed to keep passengers a safe distance from the edge of the platform, reducing the risk of accidents, such as an individual falling onto the tracks or being too close to passing trains.

By sounding the horn, train operators can alert the person to move back to a safe position. This measure ensures that the train can approach safely while minimizing the risk of harm to passengers. It also emphasizes the importance of maintaining safety protocols at station platforms, reinforcing the need for vigilance both from train staff and passengers.

The other options would not effectively address the immediate safety concern. Reducing speed might mitigate danger but does not actively inform the individual of their proximity to danger. Proceeding without stopping would be highly unsafe, as it disregards the clear risk posed by someone too close to the edge. Waiting for the next signal could lead to unnecessary delays without resolving the immediate safety issue. Thus, sounding the horn continuously stands out as the proactive and necessary response in this scenario.