When should a commercial vehicle use its horn?

Using the horn of a commercial vehicle is primarily intended as a safety device to alert other drivers or pedestrians of potential danger. This is crucial for preventing accidents and ensuring safety on the road. For instance, if a driver's attention is diverted, or if a potential collision is imminent, a horn can serve as a warning signal that may help avert a dangerous situation.

While other choices may imply various scenarios where one might consider using the horn, they do not align with the primary purpose of maintaining safety on the roadway. Expressing frustration or signaling the end of a shift does not fall within the acceptable use of the horn and may instead cause confusion or escalate tensions on the road. Similarly, using the horn when stopped for a long time does not serve a functional safety purpose, as there is no immediate danger to alert others about.