When shoring a trench with screw jacks, the minimum crew required to set the jack screws is:

When shoring a trench with screw jacks, the minimum crew required to set the jack screws is:

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Setting screw jacks to shore a trench is a controlled, coordinated task. As you turn the screw to raise or seat the shore against the trench wall, the load can shift and the jack or top plate can move unexpectedly. Having two people ensures safe control: one person operates and carefully advances the screw, while the other guides and stabilizes the jack, helps position wedges or bearing blocks, and watches for any movement or misalignment in the trench wall. This coordination reduces the risk of the shore slipping, binding, or the trench wall unexpectedly shifting, which could lead to a collapse. For these safety checks and steadying actions to happen smoothly, two workers are required, making the minimum crew two.

Setting screw jacks to shore a trench is a controlled, coordinated task. As you turn the screw to raise or seat the shore against the trench wall, the load can shift and the jack or top plate can move unexpectedly. Having two people ensures safe control: one person operates and carefully advances the screw, while the other guides and stabilizes the jack, helps position wedges or bearing blocks, and watches for any movement or misalignment in the trench wall. This coordination reduces the risk of the shore slipping, binding, or the trench wall unexpectedly shifting, which could lead to a collapse. For these safety checks and steadying actions to happen smoothly, two workers are required, making the minimum crew two.