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Nam Wan Tunnel is a tunnel in Hong Kong opened to traffic on 20 December 2009,〔http://dailynews.sina.com/bg/chn/chnpolitics/chinanews/20091023/0006802217.html〕 along with the West Tsing Yi Viaduct, East Tsing Yi Viaduct and Stonecutters Bridge. The road tunnel, which forms an important part of the HK$15 billion Route 8, linking Tsing Yi and Sha Tin in the city, began construction since 2003 and was completed in 2007. The twin-tube tunnel, built by the Highways Department of the Government of Hong Kong, is long and has three lanes in either direction in the southern part of Tsing Yi from Sai Tso Wan to Nam Wan Kok. It provides linkage between the eastern part of the New Territories and Hong Kong International Airport. The tunnel is toll-free. The twin tunnels are wide with 12 cross-passages and emergency walkways, and a portal building at each end. They were formed by blasting through granite and volcanic rocks. ==Structure== The tunnel cross section is in the form of an arch. The approximate height and width of the arch is 11.2m and 15.3m respectively. The geology comprises coarse volcanic ash tuff on the west side and medium grained granite on the eastern side. Both of these lithologies are intruded by Rhyolite dykes together with some porphyrytic granite and occasional basalt dykes. The two tubes were constructed using the drill/blast method. Temporary support for the tunnels have been provided by rock-bolts. Permanent supports have been provided by a concrete lining of varying thickness depending upon the stability of the ground. Three main types of support have been used: 400mm un-reinforced, 500mm un-reinforced, and 600mm reinforced. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Nam Wan Tunnel」の詳細全文を読む スポンサード リンク
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