I'm not sure what these guys were doing, but the job must have been made more difficult because of the height.
The base of that lift truck is about 4 stories lower than you see in the photo. It's in an alley behind the parking garage.
In the detail photo you can see the fellow on the lift passing what looks like a pipe to the fellow on the roof.
This all took place several years ago and I never did hear what they were doing. It must have been necessary, you don't go through that much trouble on a whim.
The original photos aren't very good. they were taken through an office window with an old compact camera. The sun had not fully risen and the photo was a bit dark and very noisy.
I used Lightroom to make it a bit lighter, reduce the noise and highlight the two workers.
Lightroom couldn't do anything about the dirty window that I shot through.
Like so many of my photos, these are not fine art, I'm glad a took a minute to make a couple of snapshots to remind me of the unusual activity of the day.