Now for something completely different.
Yesterday as I sat here all day long, reading stories on the Internet and putting stuff up on the blog while the electrician was working in the kitchen, I almost burned out on news. After he left, I was happy to get out of the house and read my magazine. (If I were to read my magazine at home, I wouldn't have anything to read when I'm out of the house).
The Sept. 15 New Yorker had a very interesting story ("The Long Dig; getting through the Swiss Alps the hard way") about a company in Germany that builds tunnels using special tunnel boring machines (TBMs) (or worms) which it fabricates at a factory in the Black Forest. (Unfortunately, the magazine's website carries only an abstract of the article.) The company, Herrenknecht, manufactures TBMs of all sizes, ranging from four inches in diameter for utility lines to fifty feet in diameter (and a third of a mile long) for subway, train and highway tunnels. The company is presently using the large-bore variety to create the world's longest traffic tunnel, beneath the Alps in Switzerland.
The story describes this particular machine at length, but I found it difficult to form a mental picture. (A photograph would have helped, but The New Yorker is not big on photographs to illustrate its articles.) (Sometimes a picture is worth a thousand words, as they say. In this case, a diagram would have been even better.) But I also found it difficult to imagine how the machine worked. (The article probably wasn't the most well written I've read, but on the whole I found it entertaining.)
At any rate, it's a very large and complicated machine. Here, the top photo is of the TBM they're using in Switzerland. Beneath that is a model of it. Beneath that is an even larger TBM (the world's largest) they're using in Madrid to build tunnels to decrease traffic at street level and allow for more parks and pedestrian plazas. The videos show how the machine works.
I hope you find this as fascinating as I did.