Coinciding with the World Expo 2010 in Shanghai, two 7.47-kilometer-long, three-lane road tunnels with an integrated metro line underneath were to be opened to traffic. The tunnels would connect the Pudong district with the river island of Changxing, whose inhabitants have so far had to rely on ferries to take them to the mainland. Since the Yangtze river is one of the busiest shipping routes in China, it was vital that construction work did not disrupt domestic maritime traffic. For that reason, it was decided to excavate a tunnel deep under the river, by mechanized tunnelling.
In September and December 2006, respectively, two TBM giants with a diameter of 15.43 meters took off for their undergound mission - at a depth of up to 65 meters and under the water pressure of up to 6.5 bar. The project was on a colossal scale: approx. 1,500 people were employed at the large jobiste, 2.7 million cubic meters of earth had to be removed and approx. 7,500 segment rings installed. The first machine, the S-317, reached the target shaft on Changxing island on the Yangtze river, on May 28, 2008. The S-317 followed on September 5, 2008. Thus, they are ten and twelve months faster than originally planned. The two breakthroughs represent a major milestone in mechanized tunnelling. Even the largest tunnel diameters can be safely managed and can be driven well within the time schedule.