| 摘要 |
The twin-tube tunnel acts as the inverted pendulum brought back to its stable point by the buoyancy of the tubes, the movement being damped by the isostatic assembly. This system, using the buoyancy of the assembly as stability and damping driving means, decreases the mass of the top-of-the-range structure to the benefit of anchorages which are easy to install in depths of 300 m. The cost of the assembly is less than 1/3 of a conventional bridge and less than 1/5 of a bored tunnel of the same capacity, whilst having very much more flexibility. In addition, its production is possible in all cases. Its profitability depends on the legislation of the user States; if the latter are interested, the system pays off after three years of operation. If governments are hesitant, for fear of not controlling this novel mode of mass transport which a 6-lane bridge represents, it will be necessary for interested companies to appeal to the public by means of publicity, information and referendum. From the point of view free enterprise of the object of 3 million cars and 7 million travellers per year is the profitable minimum. From the point of view of the community at large, the profitable minimum is about 1 million cars, 3 million travellers and 1 million tons of merchandise per year. Saturation for the system is: 36 million vehicles, 20 million travellers and 5 million tons of merchandise, that is 20 times more than the necessary minimum. <IMAGE>
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