The project is located in the northern region of the People’s Republic of China and was awarded to Wan Long Joint Venture, in September1997. The project consists of four tunnels for a total length of 88,700 m, with an excavation diameter of about 5.96 m. The lining is made of honeycomb pre-cast segments, connected by PVC dowels and the joints are sealed with elastomeric gaskets. The geology is mainly Limestone, Dolomite and Sandstone. Karst cavities are abundant and are often in-filled with plastic red clay. This has adversely affected the TBM’s progress. Four double shield telescopic TBMs were mobilized to cope with the very tight construction schedule and, at the after only 36 months, more than 80% of the tunnel has been bored. The article analyses the project conditions and the results of different technical solutions adopted to the project. Contracts WYRPD-C2 and WYRPD-C3 make up the chief part, though not all of the civil works for the South Main. These contracts were won by the 'Wan Long Joint Venture', a formation of IMPREGLIO S.p.A. from Italy (the leader of the joint venture with a participating share of 45%), C.M.C. of Ravenna S.a.r.l. of Italy, China Water Conservancy & Hydropower and Engineering Bureau No. 4 of China. Figure 2. Project sections for TBM drive. The WYRPD-C2 contract consists of the following work: • Tunnel four will be 6.9km long, excavated by a tunnel boring machine (TBM), with a diameter of approximately 5m, and lined with pre-cast concrete segments • Bridge canal three is to be 370m long and approximately 20m high • Tunnel number five will be 25.8km long, excavated by TBM, with a diameter of approximately 5m, and lined with pre-cast concrete segments • Culvert one is to be 530m long and to have a diameter of 5m • Culvert two will be 730m long and have a diameter of 4.2m • Tunnel six will be 14.6km in length, possibly excavated by TBM, with a diameter of approximately 5m, and lined with pre-cast concrete segments The WYRPD-C3 contract consists of the following work: • TBM with a diameter of approximately 5m and lined with pre-cast concrete segments • Flood control sluice • Open channel section approximately 460m long, built of stone 2 GEOLOGICAL CONDITIONS The entire project area is located in the influence region of Northchinese fault zone. All underground structures of Lot II and Lot III of the WYRDP are situated in layers of Cambrian limestone and dolomite stone layers. The stone layers are placed in packages and layers that are almost horizontal. Due to the mostly limestone formations very often karst phenomena have been found along the project route. Karst cavities have been mostly filled with clay, sometimes with some smaller amount of water and that have had direct influence on the reduction of TBM advance rates.