To prevent injury due to crushing between cranes and other objects, what must be used?

Using barricades is the appropriate method to prevent injury due to crushing between cranes and other objects. Barricades serve as protective barriers that help define work zones and keep personnel at a safe distance from potential hazards, such as moving cranes. They visually alert workers to the presence of dangerous equipment in motion and restrict access to areas where there may be risks of crushing or collision, hence enhancing overall site safety.

In contrast, synthetic slings are primarily used for lifting and rigging loads, without directly addressing the need for creating safe distances around moving machinery. A whip line is a type of rigging line that allows for better maneuverability but does not provide protective measures against crushing. Safety nets can help prevent falls from heights, but they are not designed to mitigate the risk of being caught between moving equipment and fixed objects. Therefore, the most effective and direct means of preventing crushing injuries is through the use of barricades.