TUNNELS - SPECIAL WORKS

In this Paper, the special works to tunnels are considered in three pa rts: the transverse passages, the pumping station and the railway cros sover. The transverse passages are of two types: cross-passages proper and piston relief ducts which allow the exchange of air masses. The P aper describes how both were constructed. The pumping station, designe d to dewater the tunnels, was of conventional design; the Paper deals essentially with the civil engineering of this structure. The railway crossover allows the linking of the north and south lines in a cylindr ical structure of constant section. The different phases of its constr uction are described.