You pretty rarely get to shut anything down. The way it's normally done in a busy environment is for a relay of bucket trucks, one on each side of the highway and one in the middle (sometimes you need more, sometimes less).

One bucket has the cable, passes it off to the next and stays there feeding it across, and so on until you have it across and the span is properly "slacked".

Not really complicated, ya just GOTTA remember to have your boom above the 18' level.....or else. [Linked Image]