World's Widest TBM Completes Digging in Shanghai The digging of the world's widest tunnel linking Shanghai with Chongming under the Yangtze river was completed on 5th September, 2008. The 7.5 km tunnel, with an inner diameter of 13.7 metres, is part of a CNY12.6 billion bridge and tunnel project to link Shanghai with Chongming Island, the country's third largest after Taiwan and Hainan.The tunnel will accommodate a six-lane expressway and a rail line. When operational in 2010, travel to Chongming from urban Shanghai will take 20 minutes. Shanghai Tunnel Engineering Co. (STEC), the builder of the tunnel, used a Herrenknecht tunnel boring machine with a diameter of 15.43 metres, the largest of its kind, to excavate under the Yangtze. The first bore was concluded last May. Click here and here. Visit www.herrenknecht.comThe tunnel has emergency passages every 270 metres connecting the parallel tubes that make up the basis of the tunnel. Another eight passages will link the highway and the metro line running in the lower part of the tunnel. Because of the length of the tunnel, designers are considering lining the tunnel with different colours and lighting styles to prevent driver fatigue. The tunnel ceiling will look like a night sky with stars.The 25.5 km tunnel and bridge project will make the transport networks on the southern and northern sides of the river more closely connected. The tunnel connects Shanghai's vast Pudong district with Changxing Island in the Yangtze, while the bridge connects Changxing and Chongming. Currently, Chongming is connected with Jiangsu province to its north.Located at the Yangtze river mouth, Chongming covers an area of 1,200 square kilometres, equal to about 20% of Shanghai's total land area. China's central government plans to turn the island into a model of an eco-friendly town in the country. Inconvenient traffic between Shanghai and Chongming blocked the development of the island. The construction of the bridge and tunnel will help attract overseas investment and make the suburb a major channel of the Yangtze river delta area. 38/08.