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There was no example of a submarine being used in an inland river in China, and the Central Government had no regulations on the management of civilian submarines, said Chen Jiasheng, an official of the Hangzhou Port and Shipping Administration Bureau.
"Till now, China still has not established such regulations, and the submarine has never been put into use," said Xu. Even if such regulations were formed and the submarine was approved for use, it still couldn't fulfill its sightseeing purpose. The strong currents produced by the submarine would threaten to destroy the city walls and houses, Xu added.
Some people insist on leaving the underwater sites undisturbed to protect them.
Leaving the ancient cities untouched in their current condition is the best protection, said Fang Minghua, Deputy Director of the Press and Publication Bureau and former Director of the Cultural Relic Bureau of Chun'an.
It is still too early to tamper with the artifacts, as there are no mature technologies to keep them intact after removal from the water, said Fang. For instance, during an exploration, the divers carried two beams of a roof to the land. Soon after the water evaporated, the beams began to wither and dry up.
Past experience indicates the wooden structures should stay in place beneath the surface rather than attempting a full excavation.
The ultimate goal of cultural relic protection was to maintain its value for education, economic benefits or historical study. But the premise of making use of the relics depended first on protecting them, said Fang.
With efforts to find a solution in a deadlock, a bold idea brought hope to the local people—building an Archimedes bridge across Qiandao Lake.
An Archimedes bridge, also called a suspended tunnel or submerged floating tunnel, is a tunnel that can float in the water. It is based on Archimedes law, from which the bridge gets its name.
When completed, the 100-meter-long bridge will be fully submerged in water. From the outside, it will look like an oval tube. Inside, there will be motorways in the middle and two railway tracks flanking them.
The bridge is anticipated to be a promising architectural technique. Compared with similar techniques like suspension bridges and sunken tunnels, it is cheaper to build and it produces less pollution, said a report on the proposed project.
Though the technique can be widely used in places like straits and inland rivers, it has to overcome some technical problems.
The Sino-Italian cooperation culminated in a treaty signed in 2004 between the Institute of Mechanics of the Chinese Academy of Sciences (CAS) and the Italian Archimedes Bridge Co., which paved the way for future construction of the bridge.
This proposal was offered by the CAS, China's leading academic institution and comprehensive research and development center in natural science, technological science and hi-tech innovation.
At the end of 2002, CAS President Lu Yongxiang visited Qiandao Lake and learned of the problems in developing the underwater cities. In July 2003, Institute of Mechanics of CAS proposed plans for the bridge to the Chun'an Government, and the two signed a cooperation agreement.
"At present, the simulation bridge has passed tests in the laboratory. The next step is to test it in a water environment similar to that of Qiandao Lake. Later we will conduct tests in Qiandao Lake," said Fang Yang, Director of the Qiandao Lake Tourist Administration.
"If the bridge is completed successfully, the tourists can appreciate the ancient cities from inside the tunnel, with no harm to the cities," said Xu.
Construction of an Archimedes bridge is a worldwide effort. Currently, seven countries are working on the technology, including Norway, Italy, Japan, China, Switzerland, Brazil and the United States. If the bridge in Qiandao Lake is completed successfully, it will be the world's first Archimedes bridge.
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