BERLIN TUNNELLING TOWARDS 2002

The rebuilding of Potsdamer Platz and Potsdamer Street in Berlin is the largest city centre construction project in Western Europe. The pre-1939 rail and road transport scheme for Berlin will be realised with some modifications. This article describes the principal engineering works, which will be a new north-south railway and trunk road, much of which will be in tunnels. Existing U-Bahn (metro) and tram routes will be extended, to form an integrated transport system. The construction of the railway tunnels and stations will cost about $2.6BN, of which the state government will contribute about $1.7BN and German railways (DB) about $0.9BN. There will be a 3.5km route length of four single-track railway tunnels, of which about 1.2km will be machine bored. The slurry shield tunnel boring machines (TBMs) will drive through mostly water-saturated sands with layers of marls, clays, silts, and boulders. Lehrter Station will be an interchange with four levels, including street level. It will be constructed in a box, composed of slurry diaphragm walls and an underwater concrete floor, which will be held down by concreted anchors; the water will then be pumped out to finish the station works. Construction began in October 1995, and the new north-south railway is scheduled to open in May 2002.