The man most distant, the one you see under the crane boom, is holding a "tag line." The purpose of that is probably to keep the bucket oriented so it does not spin. There is little else that the strength of a single person could do against the weight of that bucket. He has the most active job in the picture as he has to really pay attention to the movement and swings of the bucket.

The pile of material on the left looks like it was dumped from a truck and only a few shovels-full have been dug from it. My guess would be that it is gravel to be used as concrete aggregate, that there is a concrete mixer just off the photo to the left and that the cloth bags sitting around that pile contain portland cement.

I always marvel at the rapid progress in motorized vehicle design in the past century and a quarter. The form of some cars and trucks and machines has continued to evolve over the decades, while the form of others, such as the bulldozer on the far right, appears to have been achieved early and stuck. I’m sure there have been many tweaks in bulldozer design since 1936, but the basic shape and style seem to have clicked early on.

I see one person who's working, a couple more who might be working, and about a dozen who are perhaps thinking about working.