How many drums are needed to close the upstream shoulder?

The correct answer is based on the established guidelines for setting up temporary traffic control devices, such as drums, to manage the safe closure of a shoulder. Closing the upstream shoulder requires a specific number of drums that meet the criteria for visibility and safety for both drivers and pedestrians.

In practice, the recommended number of drums to effectively close off an upstream shoulder is five. This figure is derived from standard traffic control practices that balance visibility and a gradual tapering of traffic flow into the closed area. The five drums provide sufficient delineation to alert drivers and guide them safely past the closure, reducing the likelihood of confusion or accidents.

The other options, while numbers may appear in different contexts, do not align with the standard recommendations for this specific practice of shoulder closure. Fewer drums would not provide adequate warning or separation, while excessive drums may lead to unnecessary clutter and confusion in the traffic control setup. Therefore, five drums represent the optimal choice for achieving a safe and effective closure of the upstream shoulder.