This article describes the challenges faced by the World’s largest hard rock TBM (47.2-ft in diameter) as it tunnels through some very difficult geology while constructing a massive tunnel under Niagara Falls for hydroelectric power generation. People familiar with this site might recognize that I’m a fan of Ontario Geofish, a blogger who has posted about the Niagara Tunnel at some length. He has some additional insights into the project, the geology and rock mechanics. But this article is very nicely written and explains some of the problems they encountered with overbreak etc and how they solved them. [Source: Tunnel Business Online. Image: Tunnel Business Magazine]
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New Water Supply Tunnels Underneath New York City
Urban miners have been busy constructing a new water supply tunnel underneath New York City to supply the megalopolis with the water it needs. The miners, or sandhogs as they are known, are about halfway complete with the new tunnel which is expected to be in service by the year 2020. Work on the 60-mile tunnel began in 1970 and the total projected cost is $6 billion and is widely regarded as one of the most complex public works projects in the western hemisphere. When complete, it will help deliver 1.2 billion gallons DAILY to 8 million New Yorkers. The city currently gets its drinking water from two water supply tunnels that were constructed in the early 20th century and have not been inspected or repaired since then. More after the break. (Image credit History.com)