I've been observing an excavation that's taking place where I shop. Over recent months the yellow digger in the photo has been gradually removing earth from an area which used to be a nicely landscaped courtyard. I expect the objective it to increase rent by bringing in new retail establishments.
What's interested me is the engineering problem facing the crew. For many weeks the digger with its caterpillar tracks was at the bottom of the hillside it created. In many repetitive steps, it moved dirt up the incline and loaded it into waiting dump trucks. Now that the excavation is nearing completion, it's up top. The process has been methodical and, obviously, it works.
There's a limit to the effectiveness of the method, however, and I wonder how the contractor plans to get out the last of the earth. The digger can't return to the bottom to bring it up since it needs the incline to get itself out, yet the digger's arm isn't long enough to reach down from the top to bring up the last of the dirt. So, I keep watching as I make my daily run to the grocery.