Extreme Engineering

Iceland Tunnels (2x5)

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Fifty years after the idea of harnessing the frightening force of Iceland’s glacial rivers was first conceived, the vision is about to be realised. Around 200 miles northeast of the capital, Reykjavik, engineers are hard at work drilling 72km of tunnels deep in the mountains. Three full-face boring machines (TBMs), have been specially shipped from the US to this remote site, 100 miles south of the Arctic Circle. In fact, one has just completed work on a new subway route in New York. Manufactured by American tool company, Robbins, the TBMs each measure 7m in diameter and weigh over 80 tons. Digging an average of 25m a day, each TBM needs 3 megawatts of power to drive it. Other sections of the tunnels will have to be excavated by explosives and power tools. The tunnel’s purpose is to guide water to the valley floor from reservoirs that are also currently under construction. The cascading water will drive six turbines, each with a rated output of 115 megawatts. With a total capacity of 690 megawatts, it will be the biggest hydropower plant in Europe. The project completion is scheduled for 2009.