The DB Projekt Stuttgart–Ulm GmbH is making rapid progress with one of the technically most complex parts of the Stuttgart 21 project. The building of the tunnel at the north head of the valley crossing has progressed so far that according to the estimate of DB at the end of January, the ground could be backfilled about one year later.
Between the portal of the Feuerbach/Cannstatt Tunnels and the building of the former federal railway directorate, a tunnel link to the future Stuttgart main station is currently being built in cut-and-cover. Under the Jägerstrasse, which currently runs over a temporary bridge, part of the trough for the approach tracks has already been formed, steel fixed and concreted. The four approach tracks spread like a fan at the north head to the eight tracks in the station.
The continuation of the trough then runs under the railway directorate, two thirds of which has been laboriously underpinned on large-diameter bored piles, and under the Heilbronner Strasse. For this purpose, a former urban transit tunnel located between the east facade of the railway directorate and the Heilbronner Strasse is currently being broken out. The Heilbronner Strasse itself (which had been relocated several times during the construction period) has already been diverted onto the slab over the future trough; the base slab and side walls will be constructed later. In order to be able to construct part of the base slab in the north head, two urban transit tunnels running beneath it had to be exposed along a length of 80 m and a width of 4 m under continued operation. Parts of these tubes have already been built over. At the west end of the north head, the structure of a short part of the culvert has already been completed.
Further pictures of the underpinning of the former federal railway directorate and the building of the tunnel link to the future Stuttgart main station can be found on www.tunnel-online.info and in the tunnel App.