mark02tj
Platinum Member
.... Places like salt mines and the big tunnel boring equipment usually is wore out much faster so leaving them in place is no big deal, scrap value is about all that is lost. ....
If I remember correctly, from a History Channel show, when they dug the "Chunnel" under the English Channel they left one of the tunnel boring machines down there. Right before the English side and the French side were supposed to meet, they angled one of them down sharply and just left it in it's own tunnel.
This whole London story reminds me of a book they read to us when I was a kid - "Mike Milligan and His Steam Shovel".