In case I haven't mentioned it, I live out here amongst the idiocy of rural life*, but I work in the city, in Providence specifically. They make me park about six miles from my office which gives me a couple of nice walks each day. My path takes me through a whole lot of vacant land resulting from the relocation of a stretch of interstate highway, which has been gradually undergoing transformation.
The latest project is what I believe to be a new electrical substation. For some reason it has to be on piles, a lot of them. Watching this procedure has been fabulous entertainment. First a big crane, a really humongous auger, and the pile driver, in pieces, showed up about 400 yards away from the site. They set up the pile driver over a period of a few days, attaching and raising the boom and then attaching the driving apparatus. They flew the flag of the company from the top of the boom, which is a good 40 feet high, I would say. The body of the machine is on tank tracks and obviously has to weigh mass quantities of tons in order to counterweight the boom.
After mucking around the site with backhoes and loaders for a week or so, they finally drove the big boys over there. The piles arrived on flat bed trucks, I'd guess 25 foot long slabs of reinforced concrete. The crane was for getting them off the truck -- it turns out the pile driver does its own hoisting.
First they drill holes in the ground with the augur. The pile driver has two cables running from the top of the boom which get attached to u-bolts in the pile, one near the top and the other just above the center. Then the operator hauls the pile toward the vertical, runs the driving apparatus up the boom, and maneuvers the top of the pile into a box in the apparatus, which is an astonishingly deft feat. Rather scarily, men on the ground then push the bottom of the pile -- it's obviously perfectly balanced on the lower u-bolt -- into a fitting that holds it in place. The machine then crawls to position the pile over the appropriate augur hole and starts pounding. In the old days they worked by repeatedly dropping a weight on the top of the pile -- you probably have an image of those big weights going up and down -- but now it uses a hydraulic ram.
This machine has got to cost half a million bucks. It's not what we think of as high tech but in fact it's the culmination of probably centuries of development, since the steam engine first came into use. I haven't researched the history but obviously there has been continual refinement of materials and machinery. The kind of construction that's happening by my daily walk would not have been possible 100 years ago and probably would not have been an economically viable choice until the postwar years. What we have now is an incremental improvement since then, as far as I know, but still, this is an astonishing capability that humans have given themselves, to pound 25 feet of reinforced concrete into the ground in about 20 minutes.
I got to observe all the stages of the operation on a day when my power at home had been knocked out by a windstorm. It happens a lot here, since the power lines run through the woods, so I get to think about our state of interdependence quite a lot. When you think about it, if you were to pull one thread from the fabric of civilization, you could get the whole thing to unravel. It's astonishing that it doesn't happen, actually.