They are "clipping in" a new transmission line, the wheels are dollies in which the new wire is pulled in, they are grabbing the wire with the jib, installing a string of bells and clipping in the new wire to the bells (insulators),the line is de-energized and grounded. Can be done out of hooks but bucket trucks are jammed in anywhere they can get them, the orange jumper that you see hanging is attached to a cluster bar on the pole and to the conductor the lineman are working on, this keeps the grounded conductor and the pole at the same potential, this needs to be done because the lineman will be contacting the structure while the conductor is in their jib. Just my observation, not that anybody gives <font color="ff0000">•</font><font color="ff0000">•</font><font color="ff0000">•</font><font color="ff0000">•</font><font color="ff0000">•</font><font color="ff0000">•</font> or not.