The Buschtunnel in the south of Aachen (located on the line Aachen-Liège, which is part of the line Cologne-Bruxelles) seen from the western side on 23 June 2007. The old tube on the left is currently the oldest operational railway tunnel in Germany, it was built between 1838 and 1843. During the last two years a new tube was excavated, it is nearly finished now and shall go into service in September. The old tube used to be double-tracked, but after several renovations (with additional layers of brickwork applied several times) it is very short of space for that. So the new tube, which seems to be about the same size, will be single-tracked with enough space to meet current safety requirements. Later the old tube might be renovated to become a second single-tracked tube, but the funding for this is not yet assured, so the line will probably be single-tracked here for a while. At present the traffic is low enough to allow this, due to the construction works this section of the line is already single-tracked anyway.
While the old tube is straight, the line of the lamps in the new tube clearly shows that it is curved, but it will allow a speed of 160 km/h. A new track will be laid next to the retaining wall, where some new catenary poles can be seen, it will join the old alignment further west. In the past there was a flyover to change between right-hand traffic (in Germany) and left-hand traffic (in Belgium). The left track coming out of the tunnel, which is now cut off, used the alignment still visible at the left edge of the picture to gain height and crossed the other track further west. In the future left-hand traffic will be extended to Aachen Hbf, where a flat crossover is possible (altough this will be somehow irrelevant as long as this section stays single-tracked).
The train approaching the tunnel is R 5017 (Liège-Guillemins - Aachen Hbf), formed by the Belgian EMU 165. It will change to the left track, which is the only remaining operational track in the tunnel and in the station Aachen Süd immediately behind the tunnel. Note that the distant signal that the train is about to pass is equipped with a crocodile of the Belgian train protection system, not with the German Indusi. This system is also present at Aachen Süd (in fact the tracks in the picture should be part of this station), but not at Aachen Hbf which is regularly frequented by Belgian trains without Indusi, too. In the future the German part of the line (including Aachen Hbf) will be equipped with ETCS (European Train Control System) Level 1.

Digital photo by Christoph Schmitz (christoph.schmitz2@post.rwth-aachen.de)