Any object waved violently on or near a track is a signal to:

An object waved violently on or near a track serves as a clear and urgent signal to stop. This action is a safety measure intended to alert train crews of a potential hazard or emergency situation on the tracks. Such signals are established protocols in rail operations, indicating that there is an immediate risk that requires the train to halt in order to ensure safety for both passengers and crew, as well as to prevent accidents.

While there are scenarios where a signal to proceed with caution or to continue at normal speed might be applicable, the specific action of waving an object violently is universally recognized as an indication to stop, protecting everyone involved from possible danger.