ABSTRACT
The two curved tunnel tubes were launched under the water into the trench excavated in the riverbed. Each tunnel tube was cast in the dry dock built at the right hand side of the river. After flooding of the dock the tube was balanced so that the correct weight and stability was guaranteed. The launching equipment composed of the two pulling units and one braking unit, one pontoon and additional accessories was able to move the tunnel along the circular track into the final position. The definitive supports were built. The procedure was repeated for the second tunnel. This original method of construction made it possible to shorten the construction time, was friendly to the environment and was cheaper than the classical construction in cofferdams.
