A feasibility study commissioned in May 1980 by Cork Corporation recommended a 2-lane immersed tube tunnel as the optimum crossing mode for the Downstream Crossing of the River Lee. In 1991 this was revised to a 4-lane immersed tube tunnel. Details are given of the environmental impact study carried out together with geotechnical, hydraulic and shipping studies. The contract strategy, which involved the choice of a Design and Construct contract, is discussed. The Employer's requirements are discussed including a) watertightness, b) tunnel cross section and c) tunnel operation. For the covering abstract see IRRD 895561.
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