Symposium on key underwater tunnel technologies between China Railway Tunnel Group (CRTG) of China and TEC of Holland was held in Dongshan Hotel, Guangzhou on April 7, 2011. Mr. Hong Kairong, chief engineer of CRTG, presided over the symposium. Mr. Hans de Wit, executive chief manager of TEC, together with his 6 colleagues, joined the symposium. On the side of CRTG, about 60 technical persons joined the symposium.

Mr. Hans de Wit presented Fehmarn Belt fixed link in terms of the background, solution selection, segment fabrication, segment towing and immersion, public safety and architectural design. The total length of Fehmarn Belt fixed link is about 19km. There is a drastic competition between the tunnel solution and the bridge solution. Comparison and contrast are made between the tunnel solution and the bridge solution in terms of technology, environment protection, safety, economy and availability. On February 4, 2011, the Danish parliament determined to adopt the tunnel solution, due to the advantages of the solution both in the construction stage and in the operation stage. The total length of the tunnel is 18.1km and the immersed section is 17.6km. The overburden of the tunnel is 40m. The tunnel is provided with longitudinal ventilation, with the interval of the ventilation fans being 400m and the designed limit air velocity being 3.1m/s. Every 1.8km along the tunnel route, a special element is installed to provide space for the ventilation equipment, dust-control equipment and fire-fighting equipment. The tunnel will accommodate a 2x2 lane motorway with hard shoulders, an emergency annex utility tube and a double track railway. This will make it one of the largest fixed links on this planet. The costs for the realization of the tunnel have been estimated at EUR 5.1 billion. The costs for modification of the infrastructure at the Danish and German side of the link have been estimated at EUR 1.5 billion, which make the total cost EUR 6.6 billion. The preparation and design works for this project are expected to take another three years. The fixed link is intended to become operational at the end of 2020.

Mr. He Weiguo, chief engineer of the 2^nd design branch of China Railway Tunnel Survey and Design Institute presented the solution for Qiongzhou Strait Crossing Project in terms of engineering conditions, solution comparison, tunneling method and cross-section design. Mr. Chen Haijun presented the technologies for the design and construction of Yingpanlu Xianjiang River Crossing Tunnel.

On the symposium, extensive discussion is also made on the immersed tube tunneling method, TBM tunneling method, artificial island technology, factors that influence the selection of the bridge solution or the tunnel solution, the operation, maintenance and safety of the tunnel, aseismic countermeasures, disaster prevention and control and intelligent traffic management system.