They appear to be riggers’ assistants. The actual rigger is the guy in the red helmet.
It sounds like a sort of dangerous position.....
Job : Rigger
Salary : Median—$17.27 per hour
Employment Outlook : Fair
Definition and Nature of the Work :
Riggers help operate machines that move heavy objects including steel plates, bundles of steel rods, drilling towers, platforms, and the heavy construction equipment used to build and take down steel structures.
Riggers have many responsibilities. They decide which pulleys, booms, braces, and cables are strong enough for each job. They also must know where to attach the hooks, chains, and cables to lift a load safely. In some cases, riggers build equipment around the object to be moved, such as a tower or boom. While the object is being lifted, riggers use hand signals and other means to direct crane operators and help guide the objects into place.
Education and Training Requirements :
A high school education is recommended. Courses in mathematics, plan reading, and shop are especially valuable. English and communication courses are also important, because riggers give directions to others.