Which signal is commonly used to indicate "stop" on a construction site?

A raised hand with the palm facing the operator is universally recognized as a signal for "stop" on construction sites. This gesture clearly communicates to equipment operators that they must halt their actions immediately. The position of the hand, specifically the palm facing outward, serves as a clear and visible signal, reducing the chances of misinterpretation, which is crucial in a busy and potentially hazardous environment.

Other potential signals, such as a wave of the arm, may not convey a definitive message to the operator, as it could be interpreted in various ways depending on the context. A loud whistle can alert individuals to an issue but does not provide direct visual communication with operators who are focused on their tasks. Flashlight signals are typically used in specific situations, such as low visibility, but the standard hand signal remains the most straightforward and effective method for signaling a stop in construction scenarios.