What sound should a train or engine make when approaching a roadway work group?

When a train or engine approaches a roadway work group, it is important for the operator to communicate effectively to ensure safety. A series of short blasts on the engine horn serves as a warning to alert the work group of the approaching train. This method of signaling is recognized and established within railway safety protocols to give sufficient notice and allow the workers time to take appropriate action, such as moving to a safe location.

This practice is critical because it not only provides a clear signal that the train is approaching but also differentiates itself from other horn signals, indicating a specific warning rather than a general alert. The distinct sound patterns convey different messages, and in this case, the series of short blasts effectively communicates an urgent need for the workers to be aware of the train's proximity.

The other potential options do not convey the appropriate warning in this context. A long blast might indicate a different situation, while a single loud horn blast or no sound at all would not provide adequate warning to a group working near the tracks.