I took over 400 photos, if you are interested in details, most of them are available in a construction trip report. You can use the timestamps to find the related photos.
The Grove GMK5275 mobile crane arrived at 5:06:30 Note the boom dolly. This crane has a telescopic boom. The lattice work you see is a "jib" carried on the side of the boom. They used a jib on the Downers Grove High School job. But they didn't need it for this job, which makes crane assembly and disassembly go faster.
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The worker between the two pairs of wheels has raised the pad, extended the outrigger, and lowered the pad onto the heavy-duty pad. The worker on the right is putting a pin back into the outrigger to hold it in the extended position.
Then they built a 51-ton stack of counterweights on the truck bed and hydraulic rams were lowered into the stack to attach to a couple of pillars on the base counterweight to lift the stack up to the crane's "rear end."
One thing to note in the video below is that a worker on the roof was handling a rope at the other end of the boom. At 0:40, he arrives at the edge of the roof. (Just to the right of the tall traffic light.) At 1:20, he throws the bag over the side so that a ground worker can be ready when the end of the boom goes past the edge of the roof. My camera does HD, and, in a new window where you can go full screen, you can see the bag fall against the white backdrop of the building. You can even hear the "thunk" when it hits the ground.
13:07:40 The third, and final, load consists of the remaining boom segments and a trash bin.
Also of interest, because the boom is triangular, the middle segment was turned upside down and strapped to the first segment loaded on the trailer. You can see the details for the turning and strapping of the middle segment.